Mobile detection device and method with soil parameter online identification function

Abstract

The present invention discloses a mobile detection device and method with an online soil parameter identification function, which relates to the technical field of soil mechanical parameters and includes: a test system, a control and data acquisition system, and a frame. The test system includes a servo motor, a reducer, a multi-dimensional force sensor elastomer, a wheel axle, and a slip ring to measure the pressure and shear properties of the soil; the control system and the data acquisition system include a robotic arm and a host computer, which are used to control the test system to perform tests in a certain posture. The host computer is responsible for controlling the robotic arm and collecting and processing the data collected during the test. The frame of the mobile detection device with an online soil parameter identification function provided by the present invention includes two side brackets, corner pieces, a top cover, and a flange at the end of the robotic arm. The frame is responsible for arranging the main body of the wheel force acquisition system on the robotic arm. The wheel force acquisition system is small in size, light in weight, simple to operate, and compact in structure. It has the ability to measure soil mechanical characteristic parameters in most field environments.

Description

Technical Field

[0001] The present invention relates to the technical field of soil mechanical parameters, and in particular to a mobile detection device and method with a soil parameter online identification function. Background Art

[0002] With the continuous advancement of science and technology, humanity's exploration of nature and the expansion of its living environments are increasingly demanding higher performance from vehicles. Faced with various complex road environments, vehicle ground handling performance is facing enormous challenges. Ground mechanics is the study of the interaction between various off-road vehicles and the soil during operation. Studying ground mechanics is crucial for improving vehicle structure and enhancing off-road maneuverability. In ground mechanics, the mechanical properties of soil include its compressive and shear properties. The compressive properties of soil refer to the relationship between the vertical deformation of the ground and the resulting normal stress. Furthermore, the maximum traction that can be generated by mechanical equipment traveling on the ground is limited by the soil's tangential shear strength. Therefore, the soil's shear properties are the most important characteristic affecting the ground handling performance of moving machinery, such as automobiles. Therefore, obtaining and analyzing these two mechanical properties of soil can improve vehicle structural design and control, thereby enhancing ground handling performance.

[0003] The Bayesian instrument is the most commonly used tool for measuring these properties. It measures the normal stress on the pressure plate under a certain subsidence to determine soil compressive properties, and the shear force under a certain subsidence to determine soil shear properties. While the Bayesian instrument boasts a simple structure and ease of operation, off-road vehicles operate in complex and variable environments, and soil conditions in the same area can vary significantly. Traditional Bayesian instruments struggle to quickly and in real time obtain information on soil mechanical properties.

[0004] In the prior art, CN104527322A discloses a planetary rover wheel that integrates a six-dimensional force / torque testing function, which is used to detect the force / torque of the contact between the wheel and the soil during the movement of the planetary rover. CN111735703A discloses a portable Bayesian instrument for measuring the pressure-bearing and shear properties of soil. CN102109439B discloses a measuring instrument for measuring the pressure-bearing and shear properties of soil. Driven by a motor, the ball screw realizes linear motion and rotational motion respectively under the cooperation of the driving gear, the driven gear and the pressure-bearing shear joint, and can perform experimental measurements of the pressure-bearing properties, shear properties and cone index of soft soil. CN207336256U discloses a soil shear test tester that can comprehensively obtain the shear process and shear characteristic parameters of the soil sample, such as cohesion, internal friction angle, shear deformation modulus, etc., and realize the automation of the shear process and data recording.

[0005] However, the above patent still has many deficiencies in practical application: only the force / torque information of the interaction between the wheel and the soil during movement is obtained, which cannot well identify the mechanical property parameters of the soil; the portable Bayesian instrument is a fixed experimental platform with a relatively fixed experimental environment, which cannot meet the actual needs of online detection; the measurement method adopted in the above patent relies on the measurement principle of the traditional Bayesian instrument, and whether the soil mechanical property parameters measured by it are applicable to wheeled vehicles remains to be discussed. Summary of the Invention

[0006] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0007] In view of the above-mentioned problems, the present invention is proposed.

[0008] Therefore, the technical problem solved by the present invention is: using a robotic arm as a deployment tool and a wheel force acquisition system as a device for measuring soil mechanical properties deployed on a mobile terminal to achieve online identification of soil mechanical parameters.

[0009] To solve the above technical problems, the present invention provides the following technical solution: a mobile detection device with a soil parameter online identification function, comprising:

[0010] Wheel force collection system, subsidence detection system and robotic arm system.

[0011] As a preferred solution of the mobile detection device with online soil parameter identification function described in the present invention, the wheel force collection system body is composed of a multi-dimensional force sensor elastomer, which is connected to the wheel axle through a flat key. The axle is installed on the bearings on both sides through interference fit, and the bearings on both sides are installed on the brackets on both sides through interference fit. A slip ring is installed on the left side of the bracket to supply power to the entire wheel force collection system, and a torque control system is installed on the right side to provide torque for the wheel force collection system in the measurement of soil shear characteristics. The brackets on both sides are connected to the top cover plate through angle pieces, and the three are fixed with threads. The end flange of the robotic arm is installed on the top cover plate;

[0012] As a preferred solution of the mobile detection device with soil parameter online identification function described in the present invention, the torque control system is composed of a servo motor and a reduction gear, wherein the servo motor is fixed to the bracket by a threaded connection, the small gear in the reduction gear is installed on the output end of the servo motor, and the large gear is installed on the wheel axle, and the two are connected by a flat key, and the transmission system as a whole is sealed on the bracket by a torque control system cover, and the circuit board is installed on the inner side of the bracket and fixed on the inner ring of the multi-dimensional force sensor elastomer by a threaded connection, and a left window cover and a right cover are respectively installed between the multi-dimensional force sensor elastomer and the two side brackets, and the cover is connected to the outer ring of the elastomer by a thread to protect the circuit board;

[0013] As a preferred embodiment of the mobile detection device with online soil parameter identification function described in the present invention, the subsidence detection system is composed of a camera bracket and a subsidence detection camera. The camera bracket is mounted on the flange at the end of the robotic arm and fastened by threads. The subsidence detection camera is fixed to the end of the camera bracket by a threaded connection. The subsidence detection camera has a field of view facing the elastic body of the multi-dimensional force sensor serving as the main body of the wheel force collection system. During the experiment, subsidence images are collected, and the amount of subsidence of the wheel force collection system is output after image processing.

[0014] As a preferred solution of the mobile detection device with online soil parameter identification function described in the present invention, the robotic arm system controls the movement of the wheels and provides normal pressure for soil property measurement. The wheel force collection system can measure the bearing properties of the soil by measuring the normal force and normal settlement, and can measure the shear properties of the soil by measuring the shear stress, normal force and tangential displacement. The robotic arm and the wheel force collection system body are connected through the flange at the end of the robotic arm.

[0015] Another object of the present invention is to provide a mobile detection method with an online soil parameter identification function. The method can use a wheel force acquisition system, a wheeled structure as a detection carrier, and a more advanced robotic arm as a deployment tool, thereby broadening the use scenarios of the method as a soil mechanical parameter testing tool, simplifying the experimental process, and realizing full automation and onlineization of the experimental process, so that soil mechanical testing is no longer limited to laboratories and fixed environments.

[0016] To solve the above technical problems, the present invention provides the following technical solution: a mobile detection method with online soil parameter identification function, comprising:

[0017] Before the test, the base of the manipulator 1 was mounted on a mobile platform. The manipulator controller controlled the end of the manipulator to arrange the wheel force collection system in a vertical position on the terrain. When performing mobile detection, the manipulator controller maintained contact with the terrain at all times through force feedback from the wheel force collection system 2.

[0018] When measuring soil bearing characteristics, the robotic arm 1 applies normal pressure to the wheel force acquisition system 2, pressing the multi-dimensional force sensor elastic body 4 into the soil. The multi-dimensional force sensor collects and outputs the force conditions of the wheel force acquisition system in real time. The subsidence detection camera 11 maintains the same sampling rate to collect subsidence data. When the pressure increases and the subsidence stops increasing, the robotic arm stops driving.

[0019] The collected data is stored by the host computer and the bearing capacity of the soil is obtained. When the shear properties of the soil need to be measured, the robotic arm 1 presses the wheel force collection system 2 into the soil, the multi-dimensional force sensor outputs normal force data, and the subsidence detection camera 11 outputs the subsidence image, which is processed by the host computer to obtain the subsidence data. Then the servo drive system drives the wheel axle 14 to rotate, and the torque control system 5 outputs the angular displacement of the elastic body 4 of the multi-dimensional force sensor. At the same time, the multi-dimensional force sensor outputs the torque data under the corresponding angular displacement. When the pressure increases and the subsidence remains stable, the drive is stopped, and the host computer processes the obtained data to obtain the shear characteristic parameters of the soil.

[0020] As a preferred solution of the mobile detection method with online soil parameter identification function described in the present invention, the wheel force acquisition system includes:

[0021] The robotic arm is extended forward to place the wheel force collection system in contact with the soil. When the host computer detects the force feedback from the multi-dimensional force sensor, the wheel and soil are in contact. At the same time, the end of the robotic arm is kept perpendicular to the soil topography to collect subsidence data.

[0022] The acquisition of the subsidence data includes acquiring the subsidence image of the wheel force acquisition system in real time with a subsidence detection camera during the experiment and outputting it to a host computer for processing;

[0023] Perform perspective transformation on the collected image. Since the camera phase plane and the wheel plane always remain relatively stationary during the movement of the wheel force acquisition system, the image is transformed using a pre-calibrated perspective transformation matrix.

[0024] The perspective-transformed image is processed using the Canny edge detection algorithm to obtain a binary image of the wheel-soil boundary. The binary image is converted into a two-dimensional coordinate point set and a least squares fit is performed. The straight line obtained by fitting is used as the equivalent straight line of the wheel-soil boundary.

[0025] Perform Hough circle detection on the perspective transformed image to obtain the pixel coordinates (x0, y0) of the center of the wheel circle and the pixel coordinates r of the wheel radius p ;

[0026] The obtained wheel-soil interaction boundary equivalent line and the wheel center pixel coordinates are used to calculate the pixel distance from the wheel center to the fitting line according to the point-to-line distance formula to obtain the settlement value.

[0027] As a preferred solution of the mobile detection method with online soil parameter identification function described in the present invention, the perspective transformation is expressed as:

[0028]

[0029] in, Indicates the source and target points; Represents the target point after transformation; Represents the perspective transformation matrix, which is calculated based on the formula using the pixel coordinates of four points on the original image and the corresponding four-point coordinates on the target image as the basis;

[0030] The numerical value of the subsidence is expressed as:

[0031]

[0032] Among them, z represents the amount of subsidence, r p Indicates the pixel coordinate of the wheel radius, l p It represents the pixel distance from the wheel center to the fitting line, and r represents the actual radius of the wheel.

[0033] As a preferred solution of the mobile detection method with online soil parameter identification function of the present invention, the soil bearing characteristics measurement includes:

[0034] Keep the end of the robotic arm in a constant posture and control the wheel force collection system to press into the soil;

[0035] Collect pressure settlement data, continuously increase the normal force output of the robotic arm, press the wheel force collection system downward into the soil, and simultaneously record the normal force output data of the wheel force collection system. During this process, the settlement detection camera records the settlement image of the wheel force collection system at the same sampling rate as the wheel force collection system. The host computer calculates the settlement amount of the wheel force collection system and stops recording data until the normal pressure increases but the settlement amount no longer increases.

[0036] The pressure settlement model is used to calculate the bearing characteristic parameters of the soil. The saved concentrated normal force p and the corresponding settlement data z are input, and the function is solved using a nonlinear solver. The resulting vector It is the bearing characteristic parameter of the current soil.

[0037] As a preferred solution of the mobile detection method with online soil parameter identification function of the present invention, the pressure subsidence model is expressed as:

[0038] p(z)=k eq z n (a0+a1z+a2z2 ) m +p0

[0039] Where p represents the concentrated normal force, constants n and k eq are the pressure sinking index and equivalent parameter, respectively; a0, a1, and a2 are model fitting constants; z represents the sinking amount; p0 represents the deviation; and m represents the wheel area tracking index;

[0040] To identify the parameters, the general minimization problem is formulated as:

[0041]

[0042] where the vector of identified parameters is given by Indicates that the vector y represents the measured value of the concentrated normal force p and the sinking amount z measured through the experiment, Representation parameters and the model function of the controlled input z, and introduces a weighting factor w to avoid function divergence.

[0043] As a preferred solution of the mobile detection method with online soil parameter identification function described in the present invention, the shear characteristic parameters of the soil include:

[0044] Similar to the measurement of soil bearing characteristic parameters, the wheel force sensor is pressed into the soil while keeping the end of the robotic arm in a constant posture.

[0045] Shear displacement data collection: When the subsidence no longer increases under a certain normal pressure, the torque control system is activated to shear the soil. When the soil undergoes shear displacement, the concentrated normal force p perpendicular to the sheared soil, the soil shear force τ measured by the multi-dimensional force sensor, and the wheel force acquisition system angle α output by the torque control system are recorded and aggregated to the host computer to complete data collection;

[0046] The soil shear displacement model is used to calculate the shear characteristic parameters of the soil. The shear characteristic parameter calculation is as follows: the saved concentrated normal force p, soil shear force τ data and wheel force acquisition system angle α data are input, and the function is solved using a nonlinear solver. The vector obtained is It is the shear characteristic parameter of the current soil.

[0047] As a preferred solution of the mobile detection method with online soil parameter identification function described in the present invention, the shear displacement model is expressed as:

[0048]

[0049] Where τ represents the soil shear force, j represents the shear displacement, K represents the soil shear deformation modulus, c represents the soil cohesion, and p represents the concentrated normal force. represents the friction coefficient between soil particles;

[0050] The soil shear displacement is expressed as:

[0051]

[0052] Among them, α represents the rotation angle of the wheel force collection system, and r represents the radius of the wheel force collection system;

[0053] To identify the parameters, the general minimization problem is formulated as:

[0054]

[0055] in, The vector representing the identified parameters, the vector y is the experimentally measured value consisting of the concentrated normal force p, the soil shear force τ, and the shear displacement j, Representation parameters and the function model of the controlled input p, j, and introduces the weighting factor v to avoid function divergence.

[0056] A computer device includes a memory and a processor, wherein the memory stores a computer program, and is characterized in that the processor implements the steps of the above method when executing the computer program.

[0057] A computer-readable storage medium stores a computer program thereon, wherein the computer program implements the steps of the above method when executed by a processor.

[0058] Beneficial effects of the present invention: The mobile detection device with online soil parameter identification function provided by the present invention uses a robotic arm to control the movement mode and force condition of the wheel force acquisition system, which simplifies the mechanism while improving the applicability of the equipment to the environment. The posture of the robotic arm can be adjusted according to actual conditions to adapt to different experimental terrain scenes. The use of a wheeled structure as a measurement carrier is more in line with the interaction between the equipment and the soil under actual conditions, and the resulting data results are theoretically more rigorous and effective. In order to measure the bearing characteristics of soil and the shear characteristics of soil, two different working modes are designed. Compared with traditional measurement equipment, the experimental process is simplified and the experimental efficiency is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them:

[0060] Figure 1A schematic diagram of the overall structure of a mobile detection device with online soil parameter identification function provided by one embodiment of the present invention;

[0061] Figure 2 Another overall structural diagram of the mobile detection device with soil parameter online identification function provided by the first embodiment of the present invention;

[0062] Figure 3 A front view of a mobile detection device with a soil parameter online identification function provided by the first embodiment of the present invention;

[0063] Figure 4 An exploded view of a mobile detection device with online soil parameter identification function provided by the first embodiment of the present invention;

[0064] Figure 5 An overall flow chart of online soil parameter identification of a mobile detection method with online soil parameter identification function provided by the second embodiment of the present invention;

[0065] Figure 6 A flow chart of a subsidence detection algorithm for a mobile detection method with online soil parameter identification function provided by a second embodiment of the present invention;

[0066] Figure 7 This is an overall loading diagram of the mobile detection method with online soil parameter identification function provided by the fourth embodiment of the present invention;

[0067] Figure 8 This is a graph showing the subsidence detection results of the mobile detection method with online soil parameter identification function provided by the fourth embodiment of the present invention;

[0068] Figure 9 A diagram showing pressure subsidence test results of a mobile detection method with online soil parameter identification function provided by the fourth embodiment of the present invention;

[0069] Figure 10 This is a diagram showing the shear displacement test results of the mobile detection method with online soil parameter identification function provided by the fourth embodiment of the present invention.

[0070] In the figure: 1-robotic arm, 2-wheel force acquisition system body, 3-sinking detection module, 4-multi-dimensional force sensor elastomer, 5-torque control system, 6-slip ring, 7-side brackets, 8-corner fittings, 9-robotic arm end flange, 10-camera bracket, 11-sinking detection camera, 12-left window cover, 13-circuit board, 14-wheel axle, 15-servo motor, 16-reduction gear, 17-top cover, 18-bearing, 19-right cover. DETAILED DESCRIPTION

[0071] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is given in conjunction with the accompanying drawings. It is obvious that the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in this field without creative work should fall within the scope of protection of the present invention.

[0072] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0073] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0074] The present invention is described in detail with reference to schematic diagrams. For ease of illustration, cross-sectional views of device structures may be partially enlarged and not to scale when describing embodiments of the present invention. Furthermore, the schematic diagrams are merely illustrative and should not limit the scope of the present invention. Furthermore, in actual production, the three-dimensional dimensions of length, width, and depth should be included.

[0075] In the description of the present invention, it should be noted that the terms "upper, lower, inner, and outer" and other references to orientations or positional relationships are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first, second, or third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0076] In this disclosure, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be interpreted broadly. For example, they may refer to fixed, removable, or integral connections. They may also refer to mechanical, electrical, or direct connections, indirect connections through an intermediary, or internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in this disclosure.

[0077] Example 1

[0078] Reference Figure 1-4, which is an embodiment of the present invention, provides a mobile detection device with a soil parameter online identification function, comprising:

[0079] Wheel force collection system, subsidence detection system and robotic arm system.

[0080] The wheel force collection system consists of a multi-dimensional force sensor elastomer, which is connected to the wheel axle via a flat key. The axle is mounted on two bearings via an interference fit, and the two bearings are mounted on two brackets via an interference fit. A slip ring is installed on the left side of the bracket to power the entire wheel force collection system. A torque control system is installed on the right side to provide torque to the wheel force collection system during soil shear property measurements. The two brackets are connected to the top cover plate via angle fittings, and the three are fixed together with threads. The end flange of the robotic arm is installed on the top cover plate.

[0081] The torque control system consists of a servo motor and a reduction gear, wherein the servo motor is fixed to the bracket by a threaded connection, the small gear in the reduction gear is installed at the output end of the servo motor, and the large gear is installed on the wheel axle, and the two are connected by a flat key. The transmission system as a whole is sealed on the bracket by a torque control system cover, and the circuit board is installed on the inside of the bracket and fixed to the inner ring of the multi-dimensional force sensor elastomer by a threaded connection. A left window cover and a right cover are respectively installed between the multi-dimensional force sensor elastomer and the two side brackets. The cover is connected to the outer ring of the elastomer by a thread to protect the circuit board;

[0082] The subsidence detection system consists of a camera bracket and a subsidence detection camera. The camera bracket is mounted on the end flange of the robotic arm and fastened by threads. The subsidence detection camera is fixed to the end of the camera bracket by threaded connection. The subsidence detection camera's field of view faces the multi-dimensional force sensor elastic body as the main body of the wheel force collection system. During the experiment, the subsidence image is collected and the subsidence amount of the wheel force collection system is output after image processing.

[0083] The robotic arm system controls wheel movement and provides normal pressure for soil property measurement. The wheel force collection system can measure the bearing properties of the soil by measuring normal force and normal settlement, and can also measure the shear properties of the soil by measuring shear stress, normal force and tangential displacement. The robotic arm and the wheel force collection system body are connected through the flange at the end of the robotic arm.

[0084] like Figure 2 As shown, the mobile detection device with the function of online identification of soil parameters includes a wheel force acquisition system, a subsidence detection system and a robotic arm system.

[0085] The robotic arm system 1 controls wheel motion and provides normal pressure for soil property measurement. The wheel force acquisition system 2 measures soil compressive properties by measuring normal force and normal settlement, and soil shear properties by measuring shear stress, normal force, and tangential displacement. The robotic arm 1 and the settlement acquisition system 2 are connected via a flange 6 at the end of the robotic arm.

[0086] like Figure 3 As shown, the subsidence collection system 2 comprises a multi-dimensional force sensor elastomer 4, which is connected to the wheel axle 14 via a flat key. The axle is mounted on bearings 18 on either side via an interference fit. The bearings are then mounted on brackets 7 on either side via an interference fit. A slip ring 6 is mounted on the left side of the bracket 7 to power the entire wheel force collection system. A torque control system 5 is mounted on the right side to provide torque to the wheel force collection system during soil shear property measurements. The brackets 7 on either side are connected to the top cover plate 17 via angle fittings 8, and the three are secured together by threads. The top cover plate 17 is mounted with a flange 9 at the end of the robotic arm.

[0087] Furthermore, the camera bracket 10 is installed on the end flange 9 of the robotic arm and fastened by threads, and the subsidence detection camera 11 is fixed to the end of the camera bracket 10 by threaded connection. The field of view of the subsidence detection camera 11 is facing the multi-dimensional force sensor elastomer 4 which is the main body of the wheel force acquisition system. During the experiment, the subsidence image is collected and the subsidence amount of the wheel force acquisition system is output after image processing.

[0088] like Figure 4 As shown, the torque control system comprises a servo motor 15 and a reduction gear 16. The servo motor 15 is fixed to the bracket 7 via a threaded connection. The small gear in the reduction gear 16 is mounted on the servo motor output end, and the large gear is mounted on the axle 14. The two are connected by a flat key. The entire transmission system is sealed on the bracket 7 by the torque control system cover. The circuit board 13 is mounted on the inside of the bracket and fixed to the inner ring of the multi-dimensional force sensor elastomer via a threaded connection. A left window cover 12 and a right cover 19 are respectively installed between the multi-dimensional force sensor elastomer 4 and the two side brackets 7. The cover is connected to the outer ring of the elastomer via threads to protect the circuit board.

[0089] Example 2

[0090] Reference Figure 5-6 , which is an embodiment of the present invention, provides a mobile detection method with online soil parameter identification function, including:

[0091] Before the test, the base of robotic arm 1 was mounted on a mobile platform. The robotic arm controller controlled the distal end of the robotic arm to position the wheel force collection system perpendicular to the terrain. During mobile detection, the robotic arm controller maintained constant contact with the terrain through force feedback from wheel force collection system 2. When measuring soil pressure characteristics, robotic arm 1 applied normal pressure to wheel force collection system 2, pressing the multi-dimensional force sensor elastomer 4 into the soil. The multi-dimensional force sensor collected and output the force conditions of the wheel force collection system in real time. The subsidence detection camera 11 maintained a constant sampling rate to collect subsidence data. When the pressure increased and subsidence stopped, the robotic arm stopped driving. The collected data was stored by the host computer and the soil pressure characteristics were calculated. When measuring soil shear properties, robotic arm 1 presses wheel force acquisition system 2 into the soil. The multi-dimensional force sensor outputs normal force data, and subsidence detection camera 11 generates subsidence images, which are processed by a host computer to obtain subsidence data. The servo drive system then rotates wheel axle 14, and torque control system 5 outputs the angular displacement of elastic body 4 from the multi-dimensional force sensor. Simultaneously, the multi-dimensional force sensor generates torque data corresponding to this angular displacement. Drive is stopped when pressure increases and subsidence remains stable. The host computer processes this data to derive soil shear property parameters.

[0092] like Figure 5 As described above, step one: arranging the wheel force collection system: the robotic arm is extended forward to arrange the wheel force collection system to contact the soil. When the host computer detects the force feedback of the multi-dimensional force sensor, that is, when the wheel and soil are in contact, the end of the robotic arm is kept perpendicular to the soil terrain.

[0093] Step 2: Acquisition of subsidence amount: During the experiment, the subsidence detection camera acquires the subsidence image of the wheel force acquisition system in real time and outputs it to the host computer for processing.

[0094] Step 2.1: Perspective transformation of the sunken image: Perform perspective transformation on the captured image. Since the camera phase plane and the wheel plane always remain relatively stationary during the movement of the wheel force acquisition system, the image is transformed using a pre-calibrated perspective transformation matrix. The principle of perspective transformation is as follows:

[0095]

[0096] in, Indicates the source and target points; Represents the target point after transformation; Represents the perspective transformation matrix, which is calculated based on the formula using the pixel coordinates of four points on the original image and the corresponding four point coordinates on the target image.

[0097] Step 2.2: Wheel-soil interaction edge detection: Use the Canny edge detection algorithm to process the perspective transformed image to obtain a binary image of the wheel-soil interface, and convert the binary image into a two-dimensional coordinate point set for further processing.

[0098] Step 2.3: Fitting the wheel-soil interaction boundary: Perform least squares fitting on the above two-dimensional coordinate point set of the image, and use the straight line obtained by fitting as the equivalent straight line of the wheel-soil interaction boundary:

[0099] l=k·x+b

[0100] Step 2.4: Hough circle detection: Perform Hough circle detection on the perspective transformed image to obtain the pixel coordinates of the wheel center (x0, y0) and the pixel coordinates of the wheel radius r p ;

[0101] like Figure 6 As mentioned above, step 2.5 settlement calculation: the equivalent straight line of the wheel-soil interaction boundary and the pixel coordinates of the wheel center obtained in the above steps are used to calculate the pixel distance l from the wheel center to the fitting straight line according to the distance formula from the point to the straight line. p Since the actual radius of the wheel force collection system is known, the settlement value is calculated and expressed as:

[0102]

[0103] Among them, z represents the amount of subsidence, r p Indicates the pixel coordinate of the wheel radius, l p It represents the pixel distance from the wheel center to the fitting line, and r represents the actual radius of the wheel.

[0104] Step 3: Measure the soil bearing characteristic parameters, keep the posture of the end of the robotic arm unchanged, and control the wheel force collection system to press into the soil.

[0105] Step 3.1: Pressure and Subsidence Data Collection: Continuously increase the normal force output of the robotic arm, pressing the wheel force collection system downward into the soil while simultaneously recording the normal force output data of the wheel force collection system. During this process, the subsidence detection camera records the subsidence image of the wheel force collection system at the same sampling rate as the wheel force collection system. The host computer calculates the amount of subsidence of the wheel force collection system according to Step 2 above. Data recording ceases when the normal pressure increases but the subsidence stops.

[0106] Step 3.2: Calculate the soil bearing capacity parameters using the pressure-settlement model: The pressure-settlement model is expressed as:

[0107] p(z)=k eq z n (a0+a1z+a2z 2 ) m +p0

[0108] Where p represents the concentrated normal force, constants n and k eq are the pressure sinking index and equivalent parameter, respectively; a0, a1 and a2 are model fitting constants; z represents the sinking amount; p0 represents the deviation; and m represents the wheel area tracking index.

[0109] To identify the parameters, the general minimization problem can be formulated as:

[0110]

[0111] where the vector of identified parameters is given by Indicates that the vector y represents the measured value of the concentrated normal force p and the sinking amount z measured through the experiment, Representation parameters and the model function of the controlled input z, and introduces a weighting factor w to avoid function divergence.

[0112] Step 3.3: Calculation of pressure characteristic parameters: Input the concentrated normal force p and the corresponding settlement data z saved in step 2 into the above general minimization problem formula, use the nonlinear solver to solve the function, and the resulting vector It is the bearing characteristic parameter of the current soil.

[0113] Step 4: The mobile detection device with the soil parameter online identification function can also measure the soil shear characteristics: the same as step 3, keep the posture of the end of the robot arm unchanged and press the wheel force sensor into the soil.

[0114] Step 4.1: Shear displacement data collection: When settlement no longer increases under a certain normal pressure, the torque control system is activated to shear the soil. When the soil shears, the concentrated normal force p perpendicular to the sheared soil, the soil shear force τ, and the wheel force acquisition system angle α output by the torque control system are recorded and aggregated to the host computer to complete data collection.

[0115] Step 4.2: Calculate the shear characteristic parameters of the soil using the soil shear displacement model: The shear displacement model is expressed as

[0116]

[0117] Where τ represents the soil shear force, j represents the shear displacement, k represents the soil shear deformation modulus, c represents the soil cohesion, and p represents the concentrated normal force. It represents the friction coefficient between soil particles.

[0118] To identify the parameters, the general minimization problem can be formulated as:

[0119]

[0120] in, The vector representing the identified parameters, the vector y is the experimentally measured value consisting of the concentrated normal force p, the soil shear force τ, and the shear displacement j, Representation parameters and the function model of the controlled input p, j, and introduces the weighting factor v to avoid function divergence.

[0121] The soil shear displacement j is expressed as:

[0122]

[0123] Among them, α is the rotation angle of the wheel force collection system, and r is the radius of the wheel force collection system.

[0124] Step 4.3: Calculation of shear characteristic parameters: Input the normal pressure data p, soil shear force τ data and wheel force acquisition system rotation angle α data saved in step 4 into the above, use the nonlinear solver to solve the function, and the resulting vector It is the shear characteristic parameter of the current soil.

[0125] Example 3

[0126] An embodiment of the present invention is different from the previous two embodiments in that:

[0127] If the functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for enabling a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disk.

[0128] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0129] More specific examples (a non-exhaustive list) of computer-readable media include the following: an electrical connection with one or more wires (electronic devices), a portable computer disk cartridge (magnetic devices), a random access memory (RAM), a read-only memory (ROM), an erasable and programmable read-only memory (EPROM or flash memory), a fiber optic device, and a portable compact disc read-only memory (CDROM). In addition, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering, or processing in another suitable manner as necessary, and then stored in a computer memory.

[0130] It should be understood that various parts of the present invention can be implemented using hardware, software, firmware, or a combination thereof. In the above-described embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0131] Example 4

[0132] Reference Figure 7-10 , which is an embodiment of the present invention, provides a mobile detection device with the function of online identification of soil parameters. In order to verify the beneficial effects of the present invention, scientific demonstration is carried out through economic benefit calculation and simulation experiments.

[0133] In a preferred embodiment of the present invention, the Autolabor Pro1 of Beijing Huaqing Intelligent Technology Co., Ltd. is equipped with the proposed mobile detection device with the function of online identification of soil parameters. Figure 7The AutolaborPro1 has dimensions of 726*617*273mm, a net weight of 40kg, a load capacity of 50kg, uses a 24V lithium iron phosphate battery, has a maximum speed of 0.8m / s, a battery life of 4 hours, and features four-wheel drive and differential steering.

[0134] In a preferred embodiment of the present invention, the industrial camera ov5640 is used to verify the function of the sinking system. The specific parameters of the industrial camera are: resolution 4K; pixel 8 million; focal length 2.2mm; field of view 140°; no distortion. The image captured by the camera is input into the host computer, and the sinking value is obtained through the above step 2 processing, such as Figure 8 and as shown in Table 1.

[0135] Table 1: Subsidence values ​​obtained by processing

[0136] Detection volume Subsidence (mm) Entry angle departure angle result 28.72 32°27′47″ 24°29′41″

[0137] In a preferred embodiment of the present invention, a lightweight commercial robotic arm Unitree Z1 is used to carry the developed wheel force acquisition system. The robotic arm has 6 degrees of freedom, a deadweight of 4.3kg, a repeatability of 0.1mm, and a harmonic integrated reduction motor at the joint, which can provide a maximum force control accuracy of about 33N·m and 0.2N·m, and provides a position control interface and a force control interface. Two types of soil were used to conduct soil trough experiments to verify the soil bearing characteristic parameter identification function of the proposed system. Three soil bearing characteristic experiments were carried out to obtain discrete point data, and the average value point was used for curve fitting. The obtained settlement information was used as the horizontal coordinate, and the force output of the multi-dimensional force sensor was used as the vertical coordinate. According to steps one to three, the soil parameters are identified based on the pressure settlement model. As described in steps one to three, the soil parameters are identified based on the pressure settlement model. Figure 9 The maximum errors between the fitting curves and the experimental data are about 3.2% for Test 1 and about 2.7% for Test 2.

[0138] Table 2 Soil bearing capacity parameters determined by the experiment

[0139]

[0140] In a preferred embodiment of the present invention, a soil trough experiment was set up to verify the soil shear characteristic parameter identification function of the proposed system. Three experiments were carried out using normal pressures of 30N and 50N to obtain discrete point data. The image was drawn with soil shear displacement as the horizontal coordinate and soil shear force as the vertical coordinate. According to step 4, the soil shear characteristic parameters were identified based on the soil shear model. Figure 10 The maximum errors between the fitting curves and the experimental data are approximately 10.6% for (normal pressure 50 N) and approximately 9.4% for (normal pressure 30 N).

[0141] Table 3 Soil shear characteristic parameters determined by the experiment

[0142]

[0143] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A mobile detection device with online soil parameter identification function, characterized in that: include: Wheel force collection system, subsidence detection system and robotic arm system; The wheel force collection system is mainly composed of a multi-dimensional force sensor elastic body, which is connected to the wheel axle through a flat key. The axle is installed on the bearings on both sides through an interference fit. The bearings on both sides are installed on the brackets on both sides through an interference fit. A slip ring is installed on the left side of the bracket to supply power to the entire wheel force collection system. A torque control system is installed on the right side to provide torque for the wheel force collection system during soil shear property measurement. The brackets on both sides are connected to the top cover plate through angle pieces. The three are fixed with threads. The end flange of the robotic arm is installed on the top cover plate. The torque control system consists of a servo motor and a reduction gear, wherein the servo motor is fixed to the bracket by a threaded connection, the small gear in the reduction gear is installed at the output end of the servo motor, and the large gear is installed on the wheel axle, and the two are connected by a flat key. The transmission system as a whole is sealed on the bracket by a torque control system cover, and the circuit board is installed on the inside of the bracket and fixed to the inner ring of the multi-dimensional force sensor elastomer by a threaded connection. A left window cover and a right cover are respectively installed between the multi-dimensional force sensor elastomer and the two side brackets. The cover is connected to the outer ring of the elastomer by a thread to protect the circuit board; The subsidence detection system consists of a camera bracket and a subsidence detection camera. The camera bracket is mounted on the end flange of the robotic arm and fastened by threads. The subsidence detection camera is fixed to the end of the camera bracket by threaded connection. The subsidence detection camera's field of view faces the multi-dimensional force sensor elastic body as the main body of the wheel force collection system. During the experiment, the subsidence image is collected and the subsidence amount of the wheel force collection system is output after image processing. The robotic arm system controls wheel movement and provides normal pressure for soil property measurement. The wheel force collection system can measure the bearing properties of the soil by measuring normal force and normal settlement, and can also measure the shear properties of the soil by measuring shear stress, normal force and tangential displacement. The robotic arm and the wheel force collection system body are connected through the flange at the end of the robotic arm.

2. A mobile detection method with online soil parameter identification function, characterized in that: include: Before the test, the base of the manipulator 1 was mounted on a mobile platform. The manipulator controller controlled the end of the manipulator to arrange the wheel force collection system in a vertical position on the terrain. When performing mobile detection, the manipulator controller maintained contact with the terrain at all times through force feedback from the wheel force collection system 2. When measuring soil bearing characteristics, the robotic arm 1 applies normal pressure to the wheel force acquisition system 2, pressing the multi-dimensional force sensor elastic body 4 into the soil. The multi-dimensional force sensor collects and outputs the force conditions of the wheel force acquisition system in real time. The subsidence detection camera 11 maintains the same sampling rate to collect subsidence data. When the pressure increases and the subsidence stops increasing, the robotic arm stops driving. The collected data is stored by the host computer and the bearing capacity of the soil is obtained. When the shear properties of the soil need to be measured, the robotic arm 1 presses the wheel force collection system 2 into the soil, the multi-dimensional force sensor outputs normal force data, and the subsidence detection camera 11 outputs the subsidence image, which is processed by the host computer to obtain the subsidence data. Then the servo drive system drives the wheel axle 14 to rotate, and the torque control system 5 outputs the angular displacement of the elastic body 4 of the multi-dimensional force sensor. At the same time, the multi-dimensional force sensor outputs the torque data under the corresponding angular displacement. When the pressure increases and the subsidence remains stable, the drive is stopped, and the host computer processes the obtained data to obtain the shear characteristic parameters of the soil.

3. The mobile detection device with soil parameter online identification function according to claim 2, characterized in that: The wheel force collection system comprises: The robotic arm is extended forward to place the wheel force collection system in contact with the soil. When the host computer detects the force feedback from the multi-dimensional force sensor, the wheel and soil are in contact. At the same time, the end of the robotic arm is kept perpendicular to the soil topography to collect subsidence data. The acquisition of the subsidence data includes acquiring the subsidence image of the wheel force acquisition system in real time with a subsidence detection camera during the experiment and outputting it to a host computer for processing; Perform perspective transformation on the collected image. Since the camera phase plane and the wheel plane always remain relatively stationary during the movement of the wheel force acquisition system, the image is transformed using a pre-calibrated perspective transformation matrix. The perspective-transformed image is processed using the Canny edge detection algorithm to obtain a binary image of the wheel-soil boundary. The binary image is converted into a two-dimensional coordinate point set and a least squares fit is performed. The straight line obtained by fitting is used as the equivalent straight line of the wheel-soil boundary. Perform Hough circle detection on the perspective transformed image to obtain the pixel coordinates (x0, y0) of the center of the wheel circle and the pixel coordinates r of the wheel radius p ; The obtained wheel-soil interaction boundary equivalent line and the wheel center pixel coordinates are used to calculate the pixel distance from the wheel center to the fitting line according to the point-to-line distance formula to obtain the settlement value.

4. The mobile detection method with online soil parameter identification function according to claim 2 or 3, characterized in that: The perspective transformation is expressed as: in, Indicates the source and target points; Represents the target point after transformation; Represents the perspective transformation matrix, which is calculated based on the formula using the pixel coordinates of four points on the original image and the corresponding four-point coordinates on the target image as the basis; The numerical value of the subsidence is expressed as: Among them, z represents the amount of subsidence, r p Indicates the pixel coordinate of the wheel radius, l p It represents the pixel distance from the wheel center to the fitting line, and r represents the actual radius of the wheel.

5. The mobile detection method with online soil parameter identification function according to claim 4, characterized in that: The soil bearing characteristics measurement includes: Keep the end of the robotic arm in a constant posture and control the wheel force collection system to press into the soil; Collect pressure settlement data, continuously increase the normal force output of the robotic arm, press the wheel force collection system downward into the soil, and simultaneously record the normal force output data of the wheel force collection system. During this process, the settlement detection camera records the settlement image of the wheel force collection system at the same sampling rate as the wheel force collection system. The host computer calculates the settlement amount of the wheel force collection system and stops recording data until the normal pressure increases but the settlement amount no longer increases. The pressure settlement model is used to calculate the bearing characteristic parameters of the soil. The saved concentrated normal force p and settlement z are input and the function is solved using a nonlinear solver. The vector obtained is It is the bearing characteristic parameter of the current soil.

6. The mobile detection method with online soil parameter identification function according to claim 5, characterized in that: The pressure subsidence model is expressed as: p(z)=k eq With n (a0+a1z+a2z 2 ) m +p0 Where p represents the concentrated normal force, constants n and k eq are the pressure sinking index and equivalent parameter, respectively; a0, a1, and a2 are model fitting constants; z represents the sinking amount; p0 represents the deviation; and m represents the wheel area tracking index; To identify the parameters, the general minimization problem is formulated as: where the vector of identified parameters is given by Indicates that the vector y represents the measured value of the concentrated normal force p and the sinking amount z measured through the experiment, Representation parameters and the model function of the controlled input z, and introduces a weighting factor w to avoid function divergence.

7. The mobile detection method with online soil parameter identification function according to claim 6, characterized in that: The shear characteristic parameters of the soil include: Similar to the measurement of soil bearing characteristic parameters, the wheel force sensor is pressed into the soil while keeping the end of the robotic arm in a constant posture. Shear displacement data collection: When the subsidence no longer increases under a certain normal pressure, the torque control system is activated to shear the soil. When the soil undergoes shear displacement, the concentrated normal force p perpendicular to the sheared soil, the soil shear force τ measured by the multi-dimensional force sensor, and the wheel force acquisition system angle α output by the torque control system are recorded and aggregated to the host computer to complete data collection; The soil shear displacement model is used to calculate the shear characteristic parameters of the soil. The shear characteristic parameter calculation is as follows: the saved concentrated normal force p, soil shear force τ data and wheel force acquisition system angle α data are input, and the function is solved using a nonlinear solver. The vector obtained is It is the shear characteristic parameter of the current soil.

8. The mobile detection method with online soil parameter identification function according to claim 7, characterized in that: The shear displacement model is expressed as: Where τ represents the soil shear force, j represents the shear displacement, K represents the soil shear deformation modulus, c represents the soil cohesion, and p represents the concentrated normal force. represents the friction coefficient between soil particles; The soil shear displacement is expressed as: j＝α·r Among them, α represents the rotation angle of the wheel force collection system, and r represents the radius of the wheel force collection system; To identify the parameters, the general minimization problem is formulated as: in, The vector representing the identified parameters, the vector y is the experimentally measured value consisting of the concentrated normal force p, the soil shear force τ, and the shear displacement j, Representation parameters and the function model of the controlled input p, j, and introduces the weighting factor v to avoid function divergence.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 2 to 8 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 2 to 8 are implemented.

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