Modular agricultural robot chassis adapted to complex work environments and control method thereof

Abstract

This invention discloses a modular agricultural robot chassis adapted to complex operating environments and its control method. The chassis includes a detachable and modular body frame and at least three sets of leg modules. Each set of leg modules integrates a lifting actuator, a steering actuator, a walking unit, and a distributed control and power supply unit, which are independently installed through standardized interfaces. The lifting actuator uses a lead screw self-locking drive, and the distributed sub-controller, combined with attitude sensors, achieves local control and bus coordination, enabling the operating platform to maintain a horizontal position in complex terrain. The walking unit can be replaced with drive wheels or guide wheels, supporting flexible switching between two-wheel drive, three-wheel drive, and four-wheel drive configurations. This invention solves the problems of low modularity, poor versatility, and high energy consumption for leveling in existing chassis, and has the advantages of strong terrain adaptability, self-maintaining posture, convenient disassembly and maintenance, and high control robustness, making it suitable for various agricultural operating scenarios such as hills, mountains, and orchards.

Description

Technical Field

[0001] This invention belongs to the field of agricultural machinery technology, specifically a modular agricultural robot chassis and its control method adapted to complex working environments. It is particularly suitable for complex terrains such as orchards, hills, mountains, and facility agriculture, and can serve as a universal mobile platform for various agricultural operating equipment. Background Technology

[0002] With the development of agricultural mechanization and intelligence, mobile operating platforms and agricultural robots suitable for unstructured farmland environments are receiving increasing attention. Unlike traditional field operations, hilly, mountainous, orchard, and greenhouse environments are typically characterized by narrow row spacing, undulating terrain, and numerous obstacles. Therefore, higher requirements are placed on the terrain adaptability, posture stability, structural versatility, and functional expandability of the chassis platform.

[0003] Currently, some agricultural chassis have improved their terrain adaptability by incorporating adjustable wheel legs. For example, Chinese patent document CN120756593A discloses a four-wheel drive lifting agricultural chassis with adjustable wheelbase. It uses an electric cylinder-driven sliding square tube guide structure to raise and lower the wheels, and utilizes tilt sensors and a central controller to achieve overall frame leveling. This solution addresses the attitude control problem in complex terrain to some extent, but it still has the following shortcomings.

[0004] First, its control architecture is centralized, with all sensors and actuators connected to a single central controller. As the number of chassis wheel legs increases or real-time dynamic leveling is required, the computational load on the central controller rises sharply, wiring becomes more complex, system response delays increase, and the failure of a single node may affect the stability of the overall system.

[0005] Secondly, its lifting mechanism is driven by an electric cylinder. Electric cylinders are large and heavy, and not lightweight enough.

[0006] Third, its modular design is mainly reflected in the connection between the leg assembly and the frame, but the coupling between the various functional units inside the leg (such as drive, steering, and lifting) is still relatively high. When replacing or upgrading a certain functional component, it is necessary to disassemble the related components, resulting in insufficient maintenance convenience. At the same time, its drive form is fixed as four-wheel drive, which cannot be flexibly switched according to different working scenarios (such as light load on flat ground or complex heavy load), resulting in a prominent phenomenon of dedicated equipment, which limits its versatility and economy.

[0007] Furthermore, existing agricultural operation platforms still have room for improvement in terms of whole-vehicle transportation, relocation, and rapid on-site assembly and disassembly. Most chassis use welded or one-piece structures with fixed dimensions, making it difficult to flexibly adjust them according to crop row spacing or transportation conditions.

[0008] In summary, how to construct an agricultural robot chassis that combines high terrain adaptability, posture self-maintenance capability, robust control architecture, high modularity, and flexible configuration of drive system has become an urgent problem to be solved in current technological development. This invention is proposed precisely to address these technical problems. Summary of the Invention

[0009] In view of this, the purpose of the present invention is to provide a modular agricultural robot chassis and its control method adapted to complex working environments, which integrates lifting, steering, driving and control through detachable legs to achieve self-adjustment of attitude in multiple terrains and switching of multiple drive configurations.

[0010] To achieve the above objectives, the present invention provides the following technical solution: This invention first proposes a modular agricultural robot chassis adapted to complex working environments, including a body frame and leg modules; The vehicle frame is a platform structure consisting of multiple detachably connected crossbeams and longitudinal beams and has an operating platform. The leg modules are configured in at least three groups. Each group of leg modules is an independent assembly that integrates lifting adjustment, steering execution, walking drive and local control functions, and is detachably installed on the periphery of the vehicle frame through standardized mechanical and electrical interfaces. The leg module includes a lifting actuator, a steering actuator, a walking unit, and a distributed control and power supply unit; The lifting execution unit includes a vertically arranged screw transmission mechanism and a lifting motor that drives the screw transmission mechanism. The upper end of the lifting execution unit is connected to the vehicle frame and is used to independently adjust the support height of the leg module. The steering actuator is connected to the lower end of the lifting actuator and includes a rotating shaft and a steering motor that drives the rotating shaft to rotate around the axis, for driving the wheel assembly to steer; The walking unit includes a wheel frame; the wheel frame is connected to the lower end of the steering actuation unit, and a wheel assembly is mounted on the wheel frame. The wheel assembly is either a power-driven drive wheel assembly or a non-power-driven guide wheel assembly; the drive wheel assembly includes a wheel and a drive motor that drives the wheel. The distributed control and power supply unit includes a sub-controller, an attitude sensor, and an independent power supply mounted on the leg module. The sub-controller is electrically connected to the lifting motor, drive motor, and steering motor, and performs local control of the lifting, steering, and walking of the leg module based on the attitude information collected by the attitude sensor. The sub-controllers of each leg module are connected via bus communication to coordinate the control of the actions of each lifting actuator, thereby enabling the operating platform to maintain a horizontal posture when the chassis passes through uneven terrain; and at least some of the wheel assemblies of the leg modules are drive wheel assemblies.

[0011] Furthermore, U-shaped flanges are respectively fitted at the intersection of the crossbeam and the longitudinal beam, and the U-shaped flanges are detachably connected by screws to adjust or fix the intersection of the crossbeam and the longitudinal beam.

[0012] Furthermore, the lifting actuator includes a fixed sleeve and a sliding sleeve that is slidably fitted within the fixed sleeve with a single degree of freedom. The upper end of the sliding sleeve is provided with a top flange, which is connected to the vehicle frame via a U-shaped flange fitted on the crossbeam or longitudinal beam. The screw drive mechanism includes a T-shaped screw and a screw nut that mates with the T-shaped screw. The lower end of the T-shaped screw is connected to the lifting motor, and the screw nut is fixedly installed within the sliding sleeve. The T-shaped screw and the screw nut maintain the current support height through self-locking.

[0013] Furthermore, the lower end of the fixed sleeve is provided with a first connecting flange for connecting with the lifting motor, and a bearing support plate located below the sliding sleeve is provided inside the fixed sleeve. A first bearing is provided between the bearing support plate and the optical shaft section of the T-shaped lead screw. The output shaft of the lifting motor and the T-shaped lead screw are connected by a first coupling.

[0014] Furthermore, a power support frame is connected to the first connecting flange; the sub-controller is installed on the bottom surface of the power support frame, the independent power supply is installed on the top surface of the power support frame, and the fixing sleeve is provided with a power fixing bracket for fixing the middle and / or top of the independent power supply; the attitude sensor is installed on the top flange.

[0015] Furthermore, the steering actuation unit includes an outer tube, the rotating shaft is disposed inside the outer tube, the steering motor is mounted above the outer tube and is connected to the upper end of the rotating shaft for transmission, and the lower end of the rotating shaft is fixedly connected to the wheel frame.

[0016] Furthermore, the upper end of the outer sleeve is provided with a second connecting flange that is connected to the steering motor. Support plates are provided at intervals inside the outer sleeve. A protective sleeve is installed on the support plate and fitted outside the rotating shaft. A second bearing is provided between the rotating shaft and the protective sleeve. The output shaft of the steering motor is connected to the rotating shaft through a second coupling.

[0017] Furthermore, the bottom surface of the lifting motor is connected to the first intermediate flange, and the top surface of the steering motor is connected to the second intermediate flange. The first intermediate flange and the second intermediate flange are fixedly connected to achieve a detachable connection between the lifting actuator and the steering actuator. A wiring notch for wiring is provided between the first intermediate flange and the second intermediate flange.

[0018] This invention also proposes a control method based on a modular agricultural robot chassis adapted to complex working environments as described above, comprising the following steps: Step 1: Initialization and State Awareness Each sub-controller of the leg module completes self-test and establishes communication connection through the bus; each sub-controller obtains the initial support height of the corresponding leg module and the attitude information collected by the attitude sensor, and sends the initial state data to the main controller elected by each sub-controller. Step 2: Global Attitude Calculation and Target Determination The main controller aggregates the initial support height and attitude information of each leg module, and calculates the current pitch angle and current roll angle of the operating platform in combination with the preset chassis geometry parameters; based on the set target horizontal attitude, it determines the target pitch angle and target roll angle that the operating platform needs to achieve. Step 3: Collaborative Calculation of Height Compensation Amount The main controller runs a multi-leg cooperative leveling algorithm based on the difference between the current pitch angle and the target pitch angle, and the difference between the current roll angle and the target roll angle, to calculate the target height compensation amount required by each group of leg modules to compensate for attitude deviations, and sends each target height compensation amount to the corresponding sub-controller via the bus. Step 4: Execute the lifting command After receiving the target height compensation amount, each sub-controller converts it into the target motion parameters of the lifting motor in the corresponding lifting execution unit, and drives the lifting motor to independently adjust the support height of each leg module; Step 5: Closed-loop feedback adjustment During the lifting and lowering process, each sub-controller acquires the current support height and updated posture information of the corresponding leg module in real time and feeds it back to the main controller. The main controller determines whether the deviation between the current posture of the operating platform and the target horizontal posture exceeds a preset threshold based on the feedback information. If it does, steps three to four are repeated until the deviation converges to the preset threshold range.

[0019] Furthermore, in step one, the method for each sub-controller to elect a master controller via the bus is as follows: after each sub-controller is powered on, it broadcasts its own identification information, and determines one of the sub-controllers as the master controller according to the preset priority rules or the size of the identification information, and the remaining sub-controllers as slave controllers; if the master controller experiences a communication failure, the remaining sub-controllers will re-elect a new master controller within a preset time.

[0020] Furthermore, in step three, the method for calculating the target height compensation amount of each leg module using the multi-leg collaborative leveling algorithm is as follows: Let the coordinate system of the operating platform have its origin at the geometric center of the operating platform, the X-axis pointing in the forward direction of the chassis, and the Y-axis perpendicular to the X-axis pointing to the left. The position coordinates of each leg module in the coordinate system are: , , The number of leg modules; Based on the current pitch angle deviation and current roll angle deviation Calculate the initial height compensation for each leg module: Based on the difference between the set target working height and the current actual average height Determine the overall height adjustment amount: in: For the first The target height compensation amount for each leg module.

[0021] Furthermore, the leg module is equipped with a wheel ground load sensor; step three also includes wheel ground load balancing correction, the method of which is as follows: Let the wheel ground load sensor collect the first... The current ground load of the wheels of each leg module is The pressure measurement values ​​are compensated for interference using vertical acceleration signals. in: For the first The actual grounding load of each leg module after interference compensation; This is the vertical inertial force generated by the dynamic movement of the chassis; The equivalent unsprung mass borne by the leg module; Equivalent sprung mass; For the first The vertical acceleration values ​​are acquired in real time by the attitude sensors of each leg module; Let be the dynamic coupling coefficient of the sprung mass, and: in: This is the roll angle of the current operating platform; This refers to the current pitch angle of the operating platform; Let the target average pressure be Pressure deviation for: When the pressure of all wheels is different All are located in [ , If the condition is met, wheel ground load balancing correction is not performed; otherwise, wheel ground load balancing correction is performed, using the following method: A virtual spring-damping model is established, where each wheel is considered to be connected to the vehicle frame via a virtual spring, and the stiffness coefficient of the virtual spring is... The damping coefficient is Based on pressure deviation Calculate the height correction amount for the corresponding leg module. : in: This is the proportional correction factor, and the virtual spring stiffness factor. Related to the mechanical stiffness of the leg module; The differential correction coefficient is the same as the virtual damping coefficient. Related; The integral correction factor is used to eliminate steady-state pressure deviation; the proportional correction factor... Differential correction coefficient and integral correction factor Obtained through system identification or online adaptive adjustment; The height correction amount The target height compensation amount is superimposed on the compensation amount calculated in step three. The corrected target height compensation amount is obtained as follows: in: This is the target height compensation amount obtained after wheel ground load equalization correction.

[0022] Furthermore, the stiffness coefficient of the virtual spring-damping model and damping coefficient The method for online adjustment based on terrain type and wheel-ground contact characteristics is as follows: Each leg module's sub-controller acquires the vertical acceleration signal from its own leg module's attitude sensor in real time and calculates the root mean square value of the vertical acceleration within a preset time window. The main controller aggregates the data from each leg module. Take the average value As a characterization value of terrain roughness; based on the terrain roughness characterization value Calculate terrain factors : in: This is a preset roughness reference threshold; the rougher the terrain, the better. The larger, Approaching 1; the flatter the terrain, Approaching 0; The main controller determines the slip ratio or slip rate of each wheel. Calculate the contact characteristic factor : in: This represents the maximum slip ratio or slip rate of each wheel; The attenuation coefficient is preset; when the degree of wheel slippage or drift increases, A decrease indicates a deterioration in wheel-ground adhesion conditions; For drive wheel assemblies, slip ratio ; For guide wheel assemblies, slip ratio ; in: The angular velocity of the wheel rotation; The radius of the wheel's rolling radius; The longitudinal velocity at the wheel center is estimated by the fusion of attitude sensor and wheel speed sensor. stiffness coefficient The adjustment formula is: in: The basic stiffness coefficient; This is the terrain sensitivity coefficient; Contact sensitivity coefficient; When the terrain roughness increases, the stiffness coefficient should be increased appropriately. To improve attitude response speed; when wheel slippage or drift is severe, appropriately reduce the stiffness coefficient. To avoid erroneous adjustments caused by fluctuations in driving force; Damping coefficient The adjustment formula is: in: The basic damping coefficient; This is the terrain damping sensitivity coefficient; The contact damping sensitivity coefficient; When the terrain roughness increases, the damping coefficient should be increased appropriately. To suppress oscillations; when wheel slippage or drift is severe, the damping coefficient should be appropriately reduced. To avoid slow response.

[0023] The beneficial effects of this invention are as follows: This invention provides a modular agricultural robot chassis adapted to complex working environments. By integrating lifting, steering, driving, and distributed control through the leg modules, the following technical effects are achieved: (1) Each leg can independently adjust its support height. Combined with attitude perception and bus coordination, the operating platform can maintain a horizontal position in complex terrain in real time, greatly improving terrain adaptability and working accuracy; (2) The screw self-locking lifting mechanism ensures posture preservation during power outages, saving energy and ensuring safety; (3) The design of detachable leg modules and replaceable wheel components supports flexible switching between two-wheel drive, three-wheel drive, and four-wheel drive configurations, with strong versatility and reduced repeated investment in dedicated machines; (4) The distributed control architecture reduces wiring complexity and central computing load. Local faults do not affect the overall system, resulting in high robustness; (5) The overall structure is compact, and disassembly and maintenance are convenient. It is suitable for hilly, mountainous, and orchard scenarios, effectively reducing usage costs and improving working efficiency.

[0024] This invention presents a control method for a modular agricultural robot chassis adapted to complex operating environments. Through a distributed collaborative leveling mechanism, it achieves real-time, high-precision leveling of the operating platform in complex terrain. Specifically, each leg module independently senses attitude information, and the main controller collaboratively calculates height compensation based on global deviations and distributes commands, forming a closed-loop feedback loop. This results in rapid and highly accurate leveling response, effectively overcoming the impact of terrain undulations on operational stability. The main controller election and bus communication architecture enhance system fault tolerance; single-point failures do not affect overall operation, demonstrating strong robustness. This invention decouples attitude compensation and height adjustment, resulting in clear control logic that is easily expandable to multi-wheel configurations. It balances dynamic terrain adaptability with walking stability, significantly improving the autonomous operation capability and safety of agricultural robots in unstructured environments. Attached Figure Description

[0025] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the following figures are provided for illustration: Figure 1 This is a structural schematic diagram of an embodiment of the modular agricultural robot chassis adapted to complex working environments according to the present invention, specifically a structural schematic diagram when the vehicle leg modules are set to four and are two-wheel drive. Figure 2This is a schematic diagram of the modular agricultural robot chassis adapted to complex working environments in this embodiment, with four leg modules and four-wheel drive. Figure 3 This is a schematic diagram of the modular agricultural robot chassis adapted to complex working environments in this embodiment, with three leg modules. Figure 4 A schematic diagram of the structure when the lifting actuator and the steering actuator are assembled together; Figure 5 This is a structural schematic diagram of the lifting actuator unit; Figure 6 This is a schematic diagram of the T-shaped lead screw. Figure 7 This is a schematic diagram of the steering execution unit. Figure 8 This is a block diagram illustrating the principle of a distributed control and power supply unit. Figure 9 This is a flowchart of the control method for the modular agricultural robot chassis adapted to complex working environments according to the present invention.

[0026] Explanation of reference numerals in the attached figures: 100 - Vehicle body frame; 101 - Crossbeam; 102 - Longitudinal beam; 103 - U-shaped flange; 104 - Operating platform; 200-Leg module; 210-Lifting actuator; 211-Lifting motor; 212-Fixed sleeve; 213-Sliding sleeve; 214-Top flange; 215-T-shaped lead screw; 216-Lead screw nut; 217-Lifting motor output shaft; 218-First connecting flange; 219-Bearing support plate; 220-First bearing; 221-First coupling; 222-Power supply support frame; 223-Power supply fixing frame; 224-First intermediate flange; 230 - Steering actuator; 231 - Rotating shaft; 232 - Steering motor; 233 - Outer sleeve; 234 - Second connecting flange; 235 - Support plate; 236 - Protective sleeve; 237 - Second coupling; 238 - Second intermediate flange; 239 - Steering motor output shaft; 240-walking unit; 250 - Distributed control and power supply unit; 251 - Sub-controller; 252 - Attitude sensor; 253 - Independent power supply. Detailed Implementation

[0027] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0028] Example 1

[0029] like Figure 1-3 The diagram shown is a structural schematic of one embodiment of the modular agricultural robot chassis adapted to complex working environments according to the present invention. This embodiment provides a modular agricultural robot chassis adapted to complex working environments, including a body frame 100 and leg modules 200.

[0030] In this embodiment, the vehicle frame 100 is a platform structure composed of multiple detachably connected crossbeams 101 and longitudinal beams 102, arranged in a grid pattern. Both the crossbeams 101 and longitudinal beams 102 are made of aluminum square tubing, and U-shaped flanges 103 are fitted at their intersections. The U-shaped flanges 103 are detachably connected by screws. By loosening the screws, the fixed position of the U-shaped flanges 103 and the intersection position between the crossbeams 101 and longitudinal beams 102 can be adjusted along the length of the crossbeams 101 or longitudinal beams 102, thereby flexibly adjusting the overall size of the vehicle frame 100 to adapt to different crop row spacings or transportation conditions. The vehicle frame 100 also includes an operating platform 104, which is used to carry agricultural operation devices such as harvesting devices, spraying devices, transport containers, or inspection devices.

[0031] like Figure 1-3 As shown, in this embodiment, the leg modules 200 are configured as four groups, which are respectively installed at the four corners of the vehicle frame 100. Each leg module 200 is an independent assembly integrating lifting adjustment, steering execution, walking drive, and local control functions, and is detachably installed on the periphery of the vehicle frame 100 through standardized mechanical and electrical interfaces. Of course, in some other embodiments, the leg modules 200 can also be configured as three groups, such as... Figure 2 As shown. The number of leg modules 200 is set according to the actual application scenario, and will not be elaborated further. Specifically, the leg module 200 in this embodiment includes a lifting execution unit 210, a steering execution unit 230, a walking unit 240, and a distributed control and power supply unit 240. The specific structure of each leg module 200 is described in detail below.

[0032] (1) Lifting and lowering execution unit 210.

[0033] like Figure 4-5 As shown, the lifting actuator 210 includes a fixed sleeve 212 and a sliding sleeve 213 that is slidably fitted inside the fixed sleeve 212. A top flange 214 is welded to or fixed to the upper end of the sliding sleeve 213 by screws. The top flange 214 is fixedly connected to the vehicle frame 100 through a U-shaped flange 103 fitted on the crossbeam 101 or longitudinal beam 102, thereby realizing the detachable installation of the lifting actuator 210 and the vehicle frame 100.

[0034] The screw drive mechanism of the lifting actuator 210 includes a T-shaped screw 215 and a screw nut 216 that mates with the T-shaped screw 215. The T-shaped screw 215 is vertically disposed inside the fixed sleeve 212 and the sliding sleeve 213, and the screw nut 216 is fixedly installed on the lower end of the inner wall of the sliding sleeve 213. The lower end of the T-shaped screw 215 is connected to the lifting motor 211. In this embodiment, the lower end of the fixed sleeve 212 is provided with a first connecting flange 218 for connecting to the body of the lifting motor 211. The fixed sleeve 212 is also provided with a bearing support plate 219 located below the sliding sleeve 213. A first bearing 220 is installed in the center hole of the bearing support plate 219. The first bearing 220 is sleeved on the optical axis section of the T-shaped screw 215, providing radial support for the T-shaped screw 215. The output shaft of the lifting motor 211 is connected to the T-shaped screw 215 through a first coupling 221.

[0035] When the lifting motor 211 drives the T-shaped lead screw 215 to rotate, since the lead screw nut 216 is fixed to the sliding sleeve 213, the T-shaped lead screw 215 will cause the sliding sleeve 213 to slide up and down vertically relative to the fixed sleeve 212, thereby realizing the independent adjustment of the support height of the leg module 200. Because the T-shaped lead screw 215 and the lead screw nut 216 have a self-locking characteristic, after the lifting motor 211 stops driving, the leg module 200 can maintain the current support height by relying on self-locking, without the need for continuous power supply, thus saving energy and improving the safety and reliability of the system.

[0036] (2) Steering execution unit 230.

[0037] like Figure 4 and Figure 7 As shown, in this embodiment, the steering actuator 230 is connected to the lower end of the lifting actuator 210. The steering actuator 230 includes an outer sleeve 233, a rotating shaft 231, and a steering motor 232. The upper end of the outer sleeve 233 is provided with a second connecting flange 234 for connecting to the body of the steering motor 232. The rotating shaft 231 is coaxially disposed inside the outer sleeve 233, and the output shaft of the steering motor 232 is connected to the upper end of the rotating shaft 231 via a second coupling 237. Support plates 235 are spaced apart inside the outer sleeve 233, and a protective sleeve 236 is mounted on the support plate 235 and sleeved around the rotating shaft 231. A second bearing (not shown in the figure) is provided between the rotating shaft 231 and the protective sleeve 236 to ensure smooth rotation of the rotating shaft 231. The lower end of the rotating shaft 231 is fixedly connected to the wheel frame of the traveling unit 240. When the steering motor 232 drives the rotating shaft 231 to rotate, it can drive the entire walking unit 240 to rotate around the vertical axis, thus realizing independent steering of the wheels.

[0038] In this embodiment, the bottom surface of the lifting motor 211 is connected to a first intermediate flange 224, and the top surface of the steering motor 232 is connected to a second intermediate flange 238. The first intermediate flange 224 and the second intermediate flange 238 are fixedly connected by screws, realizing a detachable connection between the lifting actuator 210 and the steering actuator 230. A wiring notch is provided between the first intermediate flange 224 and the second intermediate flange 238 for wiring, which facilitates the arrangement of motor power lines and signal lines.

[0039] (3) Walking unit 240.

[0040] In this embodiment, the walking unit 240 includes a wheel frame and a wheel assembly mounted on the wheel frame. The top of the wheel frame is fixedly connected to the lower end of the rotating shaft 231. The wheel assembly can be a driving wheel assembly with power or a guide wheel assembly without power. The driving wheel assembly includes a wheel and a drive motor that drives the wheel. In this embodiment, the drive motor is preferably a hub motor integrated into the wheel hub. The guide wheel assembly only contains a wheel and does not have driving power.

[0041] Specifically, by changing the wheel assemblies on different leg modules 200, the chassis can flexibly switch between two-wheel drive, three-wheel drive, and four-wheel drive configurations. For example... Figure 1 As shown, there are four leg modules 200, two of which have drive wheel assemblies, and the other two have non-drive guide wheel assemblies. Figure 1 The four leg modules 200 form a two-wheel drive mechanism. For example... Figure 2 As shown, there are also four leg modules 200, but the wheel assemblies of all four leg modules 200 are all drive wheel assemblies, that is... Figure 2 The four leg modules 200 form a four-wheel drive mechanism. For example... Figure 3 As shown, there are three leg modules 200 (one in the front and two in the rear). At this time, the front leg module 200 can be replaced with a guide wheel assembly, and the two rear leg assemblies 200 can be set as drive wheel assemblies, which can form a three-wheel drive configuration with front wheel guidance and rear wheel drive, suitable for small plots and scenarios with high turning radius requirements.

[0042] (4) Distributed control and power supply unit 250.

[0043] In this embodiment, the distributed control and power supply unit 250 is mounted on the leg module 200. For example... Figure 8As shown, the distributed control and power supply unit 250 includes a sub-controller 251, an attitude sensor 252, and an independent power supply 253. In this embodiment, a power support frame 222 is connected to the side of the first connecting flange 218. The sub-controller 251 is mounted on the bottom surface of the power support frame 222, and the independent power supply 253 (preferably a lithium battery pack) is mounted on the top surface of the power support frame 222. A power fixing bracket 223 is also provided on the side wall of the fixing sleeve 212 to fix the middle and / or top of the independent power supply 253, thereby enhancing structural stability. The attitude sensor 252 is preferably a six-axis inertial measurement unit (IMU), which is mounted on the side wall of the top flange 214 to detect the local tilt angle, angular velocity, and vertical acceleration at the connection between the leg module 200 and the vehicle frame 100 in real time.

[0044] The sub-controller 251 is electrically connected to the lifting motor 211, the steering motor 232, and the drive motor (wheel hub motor), and performs local control of the lifting, steering, and walking of the leg module 200 based on the attitude information collected by the attitude sensor 252. The sub-controllers 251 of each leg module 200 communicate with each other via a CAN bus or EtherCAT bus to achieve data exchange and collaborative decision-making. Specifically, the sub-controllers 251 of each leg module 200 communicate with each other via a bus to collaboratively control the actions of each lifting actuator 210, thereby maintaining the horizontal attitude of the operating platform 104 when the chassis traverses uneven terrain.

[0045] Example 2

[0046] This embodiment provides a control method for a modular agricultural robot chassis adapted to complex working environments based on the one described in Embodiment 1. Based on a distributed control architecture, the real-time horizontal attitude adjustment of the operating platform is completed through the local sub-controller 251 of each leg module 200 communicating with the bus.

[0047] Specifically, such as Figure 9 As shown in the figure, this embodiment describes a control method for a modular agricultural robot chassis adapted to complex working environments, which includes the following steps.

[0048] Step 1: Initialization and State Awareness.

[0049] After the system is powered on, the sub-controllers 251 of each leg module 200 complete self-tests and establish communication connections through the bus. Each sub-controller 251 acquires the initial support height of the corresponding leg module 200 (obtained through the encoder of the lifting motor 211 or an external position sensor) and the attitude information (including tilt angle and angular velocity) collected by the attitude sensor 252, and sends the initial state data to the main controller elected by each sub-controller 251.

[0050] The master controller election method is as follows: After each sub-controller 251 is powered on, it broadcasts its own identification information. Based on preset priority rules or the size of the identification information, one sub-controller 251 is determined as the master controller, and the remaining sub-controllers 251 are designated as slave controllers. If the master controller experiences a communication failure, the remaining sub-controllers 251 will re-elect a new master controller within a preset time to ensure system fault tolerance.

[0051] Step 2: Global attitude calculation and target determination.

[0052] The main controller aggregates the initial support height and attitude information of each leg module 200, and calculates the current pitch angle of the operating platform by combining it with preset chassis geometry parameters (such as wheelbase 2a and track width 2b). and current roll angle Based on the user-defined target horizontal attitude (both pitch and roll angles are zero or preset operating angles), determine the target pitch and roll angles that the operating platform needs to achieve.

[0053] Step 3: Collaborative calculation of height compensation amount.

[0054] The main controller uses the difference between the current pitch angle and the target pitch angle. The difference between the current roll angle and the target roll angle The multi-leg collaborative leveling algorithm is run to calculate the target height compensation amount required by each group of leg modules 200 to compensate for attitude deviation, and the target height compensation amount is sent to the corresponding sub-controller 251 through the bus.

[0055] (1) Calculation of target height compensation.

[0056] Specifically, in this embodiment, the method for calculating the target height compensation amount of each leg module using the multi-leg collaborative leveling algorithm is as follows.

[0057] Let the coordinate system of the operating platform have its origin at the geometric center of the operating platform, the X-axis pointing in the forward direction of the chassis, and the Y-axis perpendicular to the X-axis pointing to the left. The position coordinates of each leg module in the coordinate system are: , , This refers to the number of leg modules. In this embodiment, .

[0058] Based on the current pitch angle deviation and current roll angle deviation Calculate the initial height compensation for each leg module: Based on the difference between the set target working height and the current actual average height Determine the overall height adjustment amount: in: For the first The target height compensation amount for each leg module.

[0059] (2) The target height compensation amount is corrected by equalizing the wheel ground load.

[0060] In a preferred embodiment of this example, the leg module 200 is equipped with a wheel ground load sensor, so the multi-leg collaborative leveling algorithm also includes wheel ground load balancing correction, as follows.

[0061] Let the wheel ground load sensor collect the first... The current ground load of the wheels of each leg module is The pressure measurement values ​​are compensated for interference using vertical acceleration signals. in: For the first The actual grounding load of each leg module after interference compensation; This is the vertical inertial force generated by the dynamic movement of the chassis; The equivalent unsprung mass borne by the leg module; Equivalent sprung mass; For the first The vertical acceleration values ​​are acquired in real time by the attitude sensors of each leg module; Let be the dynamic coupling coefficient of the sprung mass, and: in: This is the roll angle of the current operating platform; This is the pitch angle of the current operating platform.

[0062] equivalent unsprung mass and equivalent sprung mass Obtain it through the following methods: With the chassis stationary on a level surface, measure the steady-state readings of the pressure sensors in each leg module. Then the equivalent total load-bearing mass of the leg module 200 is: in: It is the acceleration due to gravity; Based on the design mass of each component of the 200-unit leg module, the equivalent unsprung mass is pre-set. The equivalent sprung mass is: Let the target average pressure be Pressure deviation for: When the pressure of all wheels is different All are located in [ , If the system is in a state of flux, wheel ground load balancing correction is not performed to reduce system energy consumption and mechanical wear; otherwise, wheel ground load balancing correction is performed. Specifically, the method for wheel ground load balancing correction is as follows.

[0063] A virtual spring-damping model is established, where each wheel is considered to be connected to the vehicle frame via a virtual spring, and the stiffness coefficient of the virtual spring is... The damping coefficient is Based on pressure deviation Calculate the height correction amount for the corresponding leg module. : in: This is the proportional correction factor, and the virtual spring stiffness factor. Related to the mechanical stiffness of the leg module; The differential correction coefficient is the same as the virtual damping coefficient. Related; The integral correction factor is used to eliminate steady-state pressure deviation; the proportional correction factor... Differential correction coefficient and integral correction factor Obtained through system identification or online adaptive adjustment.

[0064] The height correction amount The target height compensation amount is superimposed on the compensation amount calculated in step three. The corrected target height compensation amount is obtained as follows: in: This is the target height compensation amount obtained after wheel ground load equalization correction.

[0065] (3) Stiffness coefficient of the virtual spring-damping model and damping coefficient .

[0066] In this embodiment, the stiffness coefficient of the virtual spring-damped model and damping coefficient Adjustments are made online based on terrain type and wheel-ground contact characteristics. When the chassis is detected traveling on a hard, flat road surface, the stiffness coefficient is increased. and damping coefficient To improve attitude control accuracy; to reduce the stiffness coefficient when the chassis is traveling on soft or muddy surfaces. and damping coefficient To avoid frequent raising and lowering of the legs due to pressure fluctuations. Specifically, regarding the stiffness coefficient... and damping coefficient The method for making online adjustments is as follows.

[0067] The input to the virtual spring-damping model also includes vertical acceleration signals acquired by the attitude sensors of each leg module, to compensate for the interference of inertial forces caused by the dynamic movement of the chassis on the pressure measurement values. Specifically, the sub-controller of each leg module acquires the vertical acceleration signal from the attitude sensor of its own leg module in real time and calculates the root mean square value of the vertical acceleration within a preset time window. The main controller aggregates the data from each leg module. Take the average value As a characterization value of terrain roughness; based on the terrain roughness characterization value Calculate terrain factors : in: This is a preset roughness reference threshold; the rougher the terrain, the better. The larger, Approaching 1; the flatter the terrain, Approaching 0.

[0068] The main controller determines the slip ratio or slip rate of each wheel. Calculate the contact characteristic factor : in: This represents the maximum slip ratio or slip rate of each wheel; The attenuation coefficient is preset; when the degree of wheel slippage or drift increases, A decrease indicates a deterioration in wheel-ground adhesion conditions.

[0069] For drive wheel assemblies, slip ratio ; For guide wheel assemblies, slip ratio ; in: The angular velocity of the wheel rotation; The radius of the wheel's rolling radius; The longitudinal velocity at the wheel center is estimated by the fusion of attitude sensor and wheel speed sensor.

[0070] stiffness coefficient The adjustment formula is: in: The basic stiffness coefficient; This is the terrain sensitivity coefficient; Contact sensitivity coefficient; When the terrain roughness increases, the stiffness coefficient should be increased appropriately. To improve attitude response speed; when wheel slippage or drift is severe, appropriately reduce the stiffness coefficient. To avoid misadjustment caused by fluctuations in driving force.

[0071] Damping coefficient The adjustment formula is: in: The basic damping coefficient; This is the terrain damping sensitivity coefficient; The contact damping sensitivity coefficient; When the terrain roughness increases, the damping coefficient should be increased appropriately. To suppress oscillations; when wheel slippage or drift is severe, the damping coefficient should be appropriately reduced. To avoid slow response.

[0072] Step 4: Execution of elevation / lowering commands.

[0073] After receiving the target height compensation amount (or the corrected target height compensation amount), each sub-controller 251 converts the height compensation amount into the number of rotations or angles required for the lifting motor 211 based on the lead of the T-shaped lead screw 215 in the lead screw transmission mechanism, and drives the lifting motor 211 to move through position closed-loop control, so as to independently adjust the support height of each leg module 200.

[0074] Step 5: Closed-loop feedback adjustment.

[0075] During the lifting and lowering process, each sub-controller 251 acquires the current support height and updated attitude information of the corresponding leg module 200 in real time and feeds it back to the main controller via the bus. The main controller determines whether the deviation between the current attitude of the operating platform and the target horizontal attitude exceeds a preset threshold (e.g., ±0.5°) based on the feedback information. If it does, steps three and four are repeated to form a closed-loop feedback adjustment until the deviation converges to within the preset threshold range. In this embodiment, the closed-loop feedback adjustment frequency is not less than 50Hz to ensure real-time response capability under dynamic terrain.

[0076] Furthermore, the control method for the modular agricultural robot chassis adapted to complex working environments in this embodiment also includes a step of coordinated walking and steering control. Specifically, during chassis movement, when the main controller receives a walking command from the navigation system or remote controller, it adjusts the target velocity vector (linear velocity)... angular velocity The target steering angle and target wheel speed are decomposed into the target steering angle and target wheel speed of each leg module 200 and sent to each sub-controller 251 via the bus. Each sub-controller 251 controls the rotation angle of the corresponding steering motor 232 according to the target steering angle and controls the speed of the corresponding drive motor according to the target wheel speed, realizing independent drive and steering of the four wheels. When leveling control and walking control are executed simultaneously, the leveling control command has higher priority than the walking control command to ensure the stability of the platform.

[0077] The embodiments described above are merely preferred embodiments for fully illustrating the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention. The scope of protection of the present invention is defined by the claims.

Claims

1. A modular agricultural robot chassis adapted to complex working environments, characterized in that: Including the body frame and leg modules; The vehicle frame is a platform structure consisting of multiple detachably connected crossbeams and longitudinal beams and has an operating platform. The leg modules are configured in at least three groups. Each group of leg modules is an independent assembly that integrates lifting adjustment, steering execution, walking drive and local control functions, and is detachably installed on the periphery of the vehicle frame through standardized mechanical and electrical interfaces. The leg module includes a lifting actuator, a steering actuator, a walking unit, and a distributed control and power supply unit; The lifting execution unit includes a vertically arranged screw transmission mechanism and a lifting motor that drives the screw transmission mechanism. The upper end of the lifting execution unit is connected to the vehicle frame and is used to independently adjust the support height of the leg module. The steering actuator is connected to the lower end of the lifting actuator and includes a rotating shaft and a steering motor that drives the rotating shaft to rotate around an axis, for driving the wheel assembly to steer. The walking unit includes a wheel frame; the wheel frame is connected to the lower end of the steering actuation unit, and a wheel assembly is mounted on the wheel frame. The wheel assembly is either a power-driven drive wheel assembly or a non-power-driven guide wheel assembly; the drive wheel assembly includes a wheel and a drive motor that drives the wheel. The distributed control and power supply unit includes a sub-controller, an attitude sensor, and an independent power supply mounted on the leg module. The sub-controller is electrically connected to the lifting motor, drive motor, and steering motor, and performs local control of the lifting, steering, and walking of the leg module based on the attitude information collected by the attitude sensor. The sub-controllers of each leg module are connected via bus communication to coordinate the control of the actions of each lifting actuator, thereby enabling the operating platform to maintain a horizontal posture when the chassis passes through uneven terrain; and at least some of the wheel assemblies of the leg modules are drive wheel assemblies.

2. The modular agricultural robot chassis adapted to complex working environments according to claim 1, characterized in that: U-shaped flanges are respectively fitted at the intersection of the crossbeam and the longitudinal beam, and the U-shaped flanges are detachably connected by screws to adjust or fix the intersection of the crossbeam and the longitudinal beam.

3. The modular agricultural robot chassis adapted to complex working environments according to claim 1, characterized in that: The lifting actuator includes a fixed sleeve and a sliding sleeve that is fitted inside the fixed sleeve with a single degree of freedom. The upper end of the sliding sleeve is provided with a top flange, which is connected to the vehicle frame through a U-shaped flange fitted on the crossbeam or longitudinal beam. The screw drive mechanism includes a T-shaped screw and a screw nut that cooperates with the T-shaped screw. The lower end of the T-shaped screw is connected to the lifting motor. The screw nut is fixedly installed inside the sliding sleeve. The T-shaped screw and the screw nut maintain the current support height through self-locking.

4. The modular agricultural robot chassis adapted to complex working environments according to claim 3, characterized in that: The lower end of the fixed sleeve is provided with a first connecting flange for connecting with the lifting motor. The fixed sleeve is provided with a bearing support plate located below the sliding sleeve. A first bearing is provided between the bearing support plate and the optical shaft section of the T-shaped lead screw. The output shaft of the lifting motor and the T-shaped lead screw are connected by a first coupling.

5. The modular agricultural robot chassis adapted to complex working environments according to claim 4, characterized in that: A power support frame is connected to the first connecting flange; the sub-controller is installed on the bottom surface of the power support frame, the independent power supply is installed on the top surface of the power support frame, and the fixing sleeve is provided with a power fixing bracket for fixing the middle and / or top of the independent power supply; the attitude sensor is installed on the top flange.

6. The modular agricultural robot chassis adapted to complex working environments according to claim 1, characterized in that: The steering actuator includes an outer tube, the rotating shaft is disposed inside the outer tube, the steering motor is mounted above the outer tube and is connected to the upper end of the rotating shaft for transmission, and the lower end of the rotating shaft is fixedly connected to the wheel frame.

7. The modular agricultural robot chassis adapted to complex working environments according to claim 6, characterized in that: The upper end of the outer sleeve is provided with a second connecting flange that is connected to the steering motor. A support plate is provided inside the outer sleeve. A second bearing is provided between the support plate and the rotating shaft. The output shaft of the steering motor and the rotating shaft are connected by a second coupling.

8. The modular agricultural robot chassis adapted to complex working environments according to claim 1, characterized in that: The bottom surface of the lifting motor is connected to the first intermediate flange, and the top surface of the steering motor is connected to the second intermediate flange. The first intermediate flange and the second intermediate flange are fixedly connected to achieve a detachable connection between the lifting actuator and the steering actuator. A wiring notch for wiring is provided between the first intermediate flange and the second intermediate flange.

9. A control method based on a modular agricultural robot chassis adapted to complex working environments as described in any one of claims 1-8, characterized in that: Includes the following steps: Step 1: Initialization and State Awareness Each sub-controller of the leg module completes self-test and establishes communication connection through the bus; each sub-controller obtains the initial support height of the corresponding leg module and the attitude information collected by the attitude sensor, and sends the initial state data to the main controller elected by each sub-controller. Step 2: Global Attitude Calculation and Target Determination The main controller aggregates the initial support height and attitude information of each leg module, and calculates the current pitch angle and current roll angle of the operating platform in combination with the preset chassis geometry parameters; based on the set target horizontal attitude, it determines the target pitch angle and target roll angle that the operating platform needs to achieve. Step 3: Collaborative Calculation of Height Compensation Amount The main controller runs a multi-leg cooperative leveling algorithm based on the difference between the current pitch angle and the target pitch angle, and the difference between the current roll angle and the target roll angle, to calculate the target height compensation amount required by each group of leg modules to compensate for attitude deviations, and sends each target height compensation amount to the corresponding sub-controller via the bus. Step 4: Execution of lifting / lowering commands After receiving the target height compensation amount, each sub-controller converts it into the target motion parameters of the lifting motor in the corresponding lifting execution unit, and drives the lifting motor to independently adjust the support height of each leg module; Step 5: Closed-loop feedback adjustment During the lifting and lowering process, each sub-controller acquires the current support height and updated posture information of the corresponding leg module in real time and feeds it back to the main controller. The main controller determines whether the deviation between the current posture of the operating platform and the target horizontal posture exceeds a preset threshold based on the feedback information. If it does, steps three to four are repeated until the deviation converges to the preset threshold range.

10. The control method for a modular agricultural robot chassis adapted to complex working environments according to claim 9, characterized in that: In step one, the method for each sub-controller to elect a master controller via the bus is as follows: after each sub-controller is powered on, it broadcasts its own identification information, and determines one of the sub-controllers as the master controller according to the preset priority rules or the size of the identification information, and the remaining sub-controllers as slave controllers; if the master controller experiences a communication failure, the remaining sub-controllers will re-elect a new master controller within a preset time.

11. The control method for a modular agricultural robot chassis adapted to complex working environments according to claim 9, characterized in that: In step three, the multi-leg collaborative leveling algorithm calculates the target height compensation amount for each leg module as follows: Let the coordinate system of the operating platform have its origin at the geometric center of the operating platform, the X-axis pointing in the forward direction of the chassis, and the Y-axis perpendicular to the X-axis pointing to the left. The position coordinates of each leg module in the coordinate system are: , , The number of leg modules; Based on the current pitch angle deviation Δα and the current roll angle deviation Δβ, calculate the preliminary height compensation for each leg module: Based on the difference between the set target working height and the current actual average height Determine the overall height adjustment amount: in: For the first The target height compensation amount for each leg module.

12. The control method for a modular agricultural robot chassis adapted to complex working environments according to claim 11, characterized in that: The leg module is equipped with a wheel ground load sensor; step three also includes wheel ground load balancing correction, the method of which is as follows: Let the wheel ground load sensor collect the first... The current ground load of the wheels of each leg module is The vertical acceleration signal is used to compensate for interference in the pressure measurement values. in: For the first The actual grounding load of each leg module after interference compensation; This is the vertical inertial force generated by the dynamic movement of the chassis; The equivalent unsprung mass borne by the leg module; Equivalent sprung mass; For the first The vertical acceleration values ​​are acquired in real time by the attitude sensors of each leg module; Let be the dynamic coupling coefficient of the sprung mass, and: in: This is the roll angle of the current operating platform; This refers to the current pitch angle of the operating platform; Let the target average pressure be Pressure deviation for: When the pressure of all wheels is different All are located in [ , If the condition is met, wheel ground load balancing correction is not performed; otherwise, wheel ground load balancing correction is performed, using the following method: A virtual spring-damping model is established, where each wheel is considered to be connected to the vehicle frame via a virtual spring, and the stiffness coefficient of the virtual spring is... The damping coefficient is Based on pressure deviation Calculate the height correction amount for the corresponding leg module. : in: This is the proportional correction factor, and the virtual spring stiffness factor. Related to the mechanical stiffness of the leg module; The differential correction coefficient is the same as the virtual damping coefficient. Related; The integral correction factor is used to eliminate steady-state pressure deviation; the proportional correction factor... Differential correction coefficient and integral correction factor Obtained through system identification or online adaptive adjustment; The height correction amount The target height compensation amount is superimposed on the compensation amount calculated in step three. The corrected target height compensation amount is obtained as follows: in: This is the target height compensation amount obtained after wheel ground load equalization correction.

13. The control method for a modular agricultural robot chassis adapted to complex working environments according to claim 12, characterized in that: Stiffness coefficient of the virtual spring-damped model and damping coefficient The method for online adjustment based on terrain type and wheel-ground contact characteristics is as follows: Each leg module's sub-controller acquires the vertical acceleration signal from its own leg module's attitude sensor in real time and calculates the root mean square value of the vertical acceleration within a preset time window. The main controller aggregates the data from each leg module. Take the average value As a characterization value of terrain roughness; based on the terrain roughness characterization value Calculate terrain factors : in: This is a preset roughness reference threshold; the rougher the terrain, the better. The larger, Approaching 1; the flatter the terrain, Approaching 0; The main controller determines the slip ratio or slip rate of each wheel. Calculate the contact characteristic factor : in: This represents the maximum slip ratio or slip rate of each wheel; The preset attenuation coefficient; when the degree of wheel slippage or drift increases, A decrease indicates a deterioration in wheel-ground adhesion conditions; For drive wheel assemblies, slip ratio ; For guide wheel assemblies, slip ratio ; in: The angular velocity of the wheel rotation; The radius of the wheel's rolling radius; The longitudinal velocity at the wheel center is estimated by the fusion of attitude sensor and wheel speed sensor. stiffness coefficient The adjustment formula is: in: The basic stiffness coefficient; This is the terrain sensitivity coefficient; Contact sensitivity coefficient; When the terrain roughness increases, the stiffness coefficient should be increased appropriately. To improve attitude response speed; when wheel slippage or drift is severe, appropriately reduce the stiffness coefficient. To avoid erroneous adjustments caused by fluctuations in driving force; Damping coefficient The adjustment formula is: in: The basic damping coefficient; This is the terrain damping sensitivity coefficient; The contact damping sensitivity coefficient; When the terrain roughness increases, the damping coefficient should be increased appropriately. To suppress oscillations; when wheel slippage or drift is severe, the damping coefficient should be appropriately reduced. To avoid slow response.

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