Blue crab culture frame latent type moving trolley and control method thereof

Abstract

The invention relates to a submarine mobile trolley for a blue crab culture frame and a control method thereof. The trolley comprises a chassis frame, rollers, left and right driving wheels and a motor, and dynamic regulation and control of forward and reverse rotation and real-time rotation speed of the left and right driving wheels are achieved through a PLC control module. The wheel speed and the longitudinal and transverse speeds are obtained in real time when the trolley is controlled, real-time longitudinal force and lateral force are further calculated by establishing a driving wheel dynamic slip angle differential equation and a slip rate calculation model, coupling correction factors are introduced to construct an optimal left and right wheel rotating speed solving model, and the rotating speeds of left and right driving wheels are dynamically optimized. Iteration termination is judged through a friction utilization rate threshold value, vehicle body running gravity center balance is achieved, and running stability is guaranteed. The trolley is compact in structure and suitable for self-positioning, traction, obstacle avoidance and stable transportation of the blue crab breeding frame in the narrow space. The trolley can achieve path guiding, obstacle recognition and positioning parking, is suitable for carrying the blue crab breeding frame in a narrow channel, and is compact in structure, self-adaptive in path and stable in operation.

Description

Technical Field

[0001] The present invention belongs to the technical field of automated mobile trolleys for green crab breeding racks, and particularly relates to a latent mobile trolley for a green crab breeding rack and a control method therefor. Background Art

[0002] The green crabs cultured in China are mainly Scylla paramamosain, belonging to the phylum Arthropoda, class Malacostraca, order Decapoda, family Portunidae, and genus Scylla. In order to avoid the disadvantages of difficult management of green crabs in the breeding pond, at present, the factory farming of green crabs in the form of one crab per box has emerged, which avoids the mutual killing of green crabs, can increase the breeding density, and at the same time can reduce the impact of environmental mutations. At present, there are various types of green crab breeding boxes on the market, basically single-box designs, that is, 1 box raises 1 crab. Generally, 10 boxes are connected in a row and stacked 8-10 layers upwards and evenly placed on the green crab breeding rack. The green crab breeding boxes are connected by pipelines for water inlet and drainage. Using this mode for factory farming of green crabs can increase the breeding density many times compared with pond farming under the same area, and at the same time reduce the impact caused by sudden weather changes. During the breeding process, for green crabs at different breeding stages, in order to standardize management, the "crab apartment", that is, the green crab breeding rack, will be moved at different growth stages.

[0003] The handling of traditional green crab breeding equipment mainly relies on manual methods, which are inefficient, labor-intensive, and easily cause the green crab culture box to tilt or collide, reducing the breeding quality and production efficiency of green crabs. To solve the above problems, the present invention proposes a latent trolley movement control system and a control method therefor to achieve precise and safe handling of the green crab culture box. Summary of the Invention

[0004] The object of the present disclosure is to provide a latent trolley movement control system and a control method for transporting a green crab culture box, which can achieve automatic positioning, stable handling, accurate docking, reduce labor costs, improve handling efficiency, and ensure the safety of the green crab culture box.

[0005] One technical problem to be solved by the present disclosure is to overcome the defects in the prior art that the handling of green crab breeding racks in the breeding farm usually relies on manual or simple trolley tools, with low handling efficiency, time-consuming and laborious handling process, inaccurate movement positioning of the breeding rack, easy to tip over or tilt, and time-consuming and laborious during the movement of the green crab breeding rack.

[0006] Another technical problem solved by the present disclosure is the anti-collision protection and path dynamic adjustment during the handling of the green crab breeding rack in the breeding farm.

[0007] Another technical problem solved by the present disclosure is to improve the path tracking accuracy and autonomous positioning ability during the movement of the latent trolley for the green crab breeding rack.

[0008] Another technical problem solved by the present disclosure is that this model breaks through the limitation of traditional wheel speed control that only uses speed difference, introduces the actual force factor of the tire, takes into account the traction ability and lateral stability, significantly improves the control accuracy and safety, and is particularly suitable for the automated aquaculture logistics scenario with high load sensitivity and high stability requirements.

[0009] Generally, in one aspect, there is a latent mobile trolley for a mud crab breeding rack. The trolley is used to move to the lower part of the mud crab breeding rack according to an instruction and tow the mud crab breeding rack to a desired position. The trolley includes:

[0010] A chassis frame;

[0011] Trolley rollers located at the four vertices of the bottom of the chassis frame;

[0012] A left drive wheel and a right drive wheel;

[0013] A first motor and a second motor, where the first motor provides driving force for the left drive wheel; the second motor provides driving force for the right drive wheel;

[0014] A PLC control module for controlling the forward and reverse rotations of the first motor and the second motor, and for the left drive wheel and the right drive wheel to rotate at the optimal real-time rotational speeds of the left drive wheel and the right drive wheel respectively;

[0015] Two wheel speed encoders respectively used to monitor the real-time rotational speeds of the left drive wheel and the right drive wheel in real time;

[0016] Two longitudinal speed sensors respectively used to monitor the longitudinal speeds of the left drive wheel and the right drive wheel in real time;

[0017] Two lateral speed sensors respectively used to monitor the lateral speeds of the left drive wheel and the right drive wheel in real time;

[0018] Two power supply batteries respectively used to supply power to the left drive wheel and the right drive wheel.

[0019] In one embodiment, the trolley further includes a first lidar sensor and a second lidar sensor respectively used to scan obstacles in front of and behind the trolley.

[0020] In another embodiment, the trolley further includes a first magnetic sensor and a second magnetic sensor for identifying the magnetic navigation path, and for identifying whether the current pose of the trolley is centered or deviated from the specified target path and for point position identification at the crossroads.

[0021] In yet another embodiment, one roller is respectively arranged at the four vertices of the bottom of the mud crab breeding rack.

[0022] Another embodiment provides a control method applied to the trolley as described above, including the following steps:

[0023] Initialize positioning, determine the initial pose of the trolley and obtain the magnetic navigation path, and acquire the surrounding environment information to establish an initial map;

[0024] Path tracking, control the trolley to move along the magnetic navigation path, and in real-time feedback the magnetic deviation information to the PLC control module, adjust the left drive wheel side angle and the right drive wheel side angle of the trolley, so that the centroid of the trolley always coincides with the path point on the magnetic navigation path, and gradually approach the crab breeding rack to be moved according to the magnetic navigation path;

[0025] After reaching the docking point where the crab breeding rack contacts the trolley, the trolley will engage the crab breeding rack to be moved with its own chassis frame;

[0026] The trolley transports the crab breeding rack to the target position according to the navigation path of the PLC control module, and maintains the balance of the frame load by optimizing the wheel speed.

[0027] In an alternative variation of this embodiment, during the process of transporting the crab breeding rack to the target position, it includes:

[0028] S1: Real-time obtain the longitudinal speed V x,L of the left drive wheel, the longitudinal speed V x,R of the right drive wheel, the lateral speed V y,L of the left drive wheel, and the lateral speed V y,R of the right drive wheel, the angular velocity ω L of the left drive wheel, and the angular velocity ω R of the right drive wheel;

[0029] S2: Calculate the dynamic side slip angle of the left drive wheel and the dynamic side slip angle of the right drive wheel, the slip ratio of the left drive wheel, and the slip ratio of the right drive wheel according to the real-time obtained data;

[0030] S3: Calculate the real-time lateral force of the left drive wheel and the right drive wheel, and the real-time longitudinal force of the left drive wheel and the right drive wheel;

[0031] S4: Use the lateral force calculated in step S3 for the real-time dynamics control of the trolley, construct a solution model for the optimal real-time rotational speed of the left drive wheel and the optimal real-time rotational speed of the right drive wheel, dynamically optimize the real-time rotational speeds of the left and right drive wheels, and achieve the driving with the vehicle center of gravity always maintaining a balanced state.

[0032] In yet another additional embodiment, step S2 includes:

[0033] S21: Construct a differential equation for the dynamic side slip angle of the left drive wheel:

[0034] Construct the differential equation of the dynamic sideslip angle of the right driving wheel:

[0035] Among them, σ is the relaxation length of the tire sideslip angle; α L 、α R are the dynamic sideslip angles of the left driving wheel and the right driving wheel respectively; are the real-time change rates of the sideslip angles of the left driving wheel and the right driving wheel respectively.

[0036] S22: Solve the differential equation constructed in the S21 step by using the discrete numerical solution method, and obtain the dynamic sideslip angle α of the left driving wheel L 、the dynamic sideslip angle α of the right driving wheel R ;

[0037] S23: Calculate the slip ratio λ of the left driving wheel L and the slip ratio λ of the right driving wheel R :

[0038]

[0039] Among them, r w is the tire radius of the left driving wheel (33) and the right driving wheel (34) of the trolley; ω L is the rotational angular velocity of the left driving wheel, ω R is the rotational angular velocity of the right driving wheel; max(a, b) is a function that takes the larger value of a and b.

[0040] In still another embodiment, the formulas for calculating the real-time lateral force of the left driving wheel and the real-time lateral force of the right driving wheel in the S3 step are as follows:

[0041] F y,i =D y sin[C y arctan((1 - E y )B y α i + E y arctan(B y α i ))];

[0042] Among them, i = L or R; D y is the amplitude of the lateral force of the driving wheel, D y = - 3960; C y is the lateral force curvature factor, C y =1.1930; E y is the lateral force curvature adjustment factor, E y = - 1.0030; B y is the lateral force stiffness factor, which controls the lateral force calculation model for α iThe sensitivity of B y =-9.9389;

[0043] The formulas for calculating the real-time longitudinal force of the left driving wheel and the real-time longitudinal force of the right driving wheel are as follows:

[0044] F x,i =D x ·sin[C x ·arctan(B x λ i -E x (B x λ i -arctan(B x λ i )))];

[0045] Among them,; D x is the amplitude of the longitudinal force of the driving wheel, D x =98.1; C x is the longitudinal force curvature factor, C x =1.1800; E x is the longitudinal force curvature adjustment factor, E x =-0.8024; B x is the longitudinal force stiffness factor B x =-7.7911.

[0046] In still another embodiment, the step S4 includes the following steps:

[0047] S41: The optimal real-time rotational speed solving models for the left driving wheel and the right driving wheel are constructed as follows:

[0048]

[0049] Among them, G y,L 、G y,R are the lateral force slip influence sub-factors of the left driving wheel and the right driving wheel respectively; G x,L 、G x,R are the longitudinal force sideslip influence factors of the left driving wheel and the right driving wheel respectively; η y is the lateral force difference weight coefficient, η x is the longitudinal force difference weight coefficient; ω L,min 、ω L,max are the minimum threshold and the maximum threshold of the real-time rotational speed of the left driving wheel respectively; ω R,min 、ω R,max are the minimum threshold and the maximum threshold of the real-time rotational speed of the right driving wheel respectively; α L,min 、α L,max are the minimum threshold and the maximum threshold of the sideslip angle of the left driving wheel respectively; α R,min 、αR,max are the minimum threshold and the maximum threshold of the right driving wheel sideslip angle respectively; λ L,min , λ L,max are the minimum threshold and the maximum threshold of the left driving wheel slip ratio respectively; λ R,min , λ R,max are the minimum threshold and the maximum threshold of the right driving wheel slip ratio respectively; λ L and l R are the lateral vertical distances from the left driving wheel and the right driving wheel to the center of gravity of the vehicle respectively;

[0050] S42: Substitute the optimal real-time rotational speed ω L,best of the optimal left driving wheel and the optimal real-time rotational speed ω R,best of the optimal right driving wheel obtained in step S41 into step S2 to solve the lateral angles α i,best of the left and right driving wheels and the slip ratio λ i,best at this time, and further substitute them into the calculation formulas of the real-time lateral force of the left driving wheel and the real-time lateral force of the right driving wheel in step S3 to obtain F y,i (α i,best ) and substitute them into the calculation formulas of the real-time longitudinal force of the left driving wheel and the real-time longitudinal force of the right driving wheel in step S3 to obtain F x,i (λ i,best );

[0051] S43: Respectively determine whether the friction utilization rates μ i (λ i,best , α i,best ) of the left driving wheel and the right driving wheel are within their respective friction utilization threshold ranges:

[0052] The calculation formula of the friction utilization rate μ i (λ i,best , α i,best ) is as follows:

[0053]

[0054] The friction utilization threshold range is [0.70, 0.90];

[0055] If the friction utilization rates μ i (λ i,best , α i,best ) of the left driving wheel and the right driving wheel are both within the friction utilization threshold range, output the optimal real-time rotational speed ω L,best of the optimal left driving wheel and the optimal real-time rotational speed ω R,best of the optimal right driving wheel obtained in step S41; otherwise, repeat steps S41 - S43.

[0056] In an additional embodiment, G y,L , G y,R , G x,L, G x,R The calculation formula of is as follows:

[0057]

[0058] Among them, S H,x is the first horizontal displacement factor, and S H,y is the second horizontal displacement factor;

[0059] Brief Description of the Drawings

[0060] The present invention will be described in more detail below based on embodiments and with reference to the drawings. Among them:

[0061] Figure 1 shows the relationship that the stealth vehicle is located under the mud crab breeding rack and carries it to the target position;

[0062] Figure 2 shows the overall structure of the stealth mobile vehicle of the mud crab breeding rack;

[0063] Figure 3 shows the top view structure of the stealth mobile vehicle of the mud crab breeding rack;

[0064] Figure 4 shows the internal structure of the stealth mobile vehicle of the mud crab breeding rack from another perspective;

[0065] Figure 5 shows the bottom view structure of the stealth mobile vehicle of the inclined breeding rack;

[0066] Figure 6 shows the positional relationship of the wheels of the stealth vehicle in the wheel body coordinate system, the vehicle body coordinate system, and the earth coordinate system;

[0067] Figure 7 shows the forces, sideslip angles, and steering angles of the left and right drive wheels of the stealth vehicle in their respective wheel coordinate systems;

[0068] Figure 8 shows the cross - influence of the slip ratio and the sideslip angle on the longitudinal force;

[0069] Figure 9 shows the cross - influence of the slip ratio and the sideslip angle on the lateral force;

[0070] Figure 10 shows the top view of the vehicle under eight different working conditions;

[0071] Figure 11 shows the influence of the slip ratio and the sideslip angle on the friction utilization rate of the left drive wheel;

[0072] Figure 12Shows the situation where the friction utilization rate of the right drive wheel is affected by the slip ratio and the sideslip angle;

[0073] Figure 13 Shows the value points of the friction utilization rates of the left and right drive wheels varying with the slip ratio or the sideslip angle under eight working conditions. Specific implementation manner

[0074] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0075] Figure 2 Shows a schematic diagram of the overall structure of a latent mobile trolley for a mud crab breeding rack. The trolley is used to move to Figure 1 the lower part of the mud crab breeding rack 1 shown, and tow the mud crab breeding rack 1 to a desired position. It is characterized in that Figure 2 、 Figure 3 、 Figure 4 the trolley 3 shown includes:

[0076] A chassis frame 31;

[0077] Trolley rollers 32 located at the four vertices at the bottom of the chassis frame;

[0078] A left drive wheel 33 and a right drive wheel 34;

[0079] A first motor 331 and a second motor 341. The first motor 331 provides driving force for the left drive wheel 33; the second motor 341 provides driving force for the right drive wheel 34;

[0080] A PLC control module 39 for controlling the forward and reverse rotations of the first motor 331 and the second motor 341, and the left drive wheel 33 and the right drive wheel 34 rotate at the optimal real-time rotational speeds of the left drive wheel and the right drive wheel respectively;

[0081] Two wheel speed encoders, respectively used to monitor the real-time rotational speeds of the left drive wheel 33 and the right drive wheel 34 in real time;

[0082] The two wheel speed encoders are respectively a first wheel speed encoder and a second wheel speed encoder. The first wheel speed encoder monitors the real-time rotational speed of the left drive wheel 33 in real time, and the second wheel speed encoder monitors the real-time rotational speed of the right drive wheel 34 in real time;

[0083] Two longitudinal speed sensors are respectively used to monitor the longitudinal speeds of the left driving wheel 33 and the right driving wheel 34 in real time; both of the two longitudinal speed sensors can adopt laser speedometers or both adopt optical speed measurement modules, including a first longitudinal speed sensor and a second longitudinal speed sensor. The first longitudinal speed sensor is used to monitor the longitudinal speed V of the left driving wheel 33 x,L and the second longitudinal speed sensor is used to monitor the longitudinal speed V of the right driving wheel 34 x,R ;

[0084] Two lateral speed sensors are respectively used to monitor the lateral speeds of the left driving wheel 33 and the right driving wheel 34 in real time; the two lateral speed sensors are installed close to the side of the tire by using a biaxial IMU module, including a first lateral speed sensor and a second lateral speed sensor. The first lateral speed sensor is used to monitor the lateral speed V of the left driving wheel 33 y,L and the second lateral speed sensor is used to monitor the lateral speed sensor V of the right driving wheel 34 y,R .

[0085] Figure 5 The two power supply batteries shown include a first power supply battery 401 and a second power supply battery 411. The first power supply battery 401 is located inside the first battery module 40, and the second power supply battery 411 is located inside the second battery module 41. The first power supply battery 401 is used to supply power to the left driving wheel 33, and the second right driving wheel 34 is supplied with power.

[0086] After the real-time information collected by the wheel speed encoder, the longitudinal speed sensor and the lateral speed sensor is transmitted to the PLC control module, the PLC control module performs fusion analysis and constructs an optimal wheel speed calculation model. By adjusting the rotational speeds of the left and right driving wheels in real time, the vehicle can drive smoothly, effectively avoiding the risk of rollover caused by vehicle body tilt or uneven load. At the same time, independent power supply battery modules are respectively equipped on the left and right sides of the vehicle body to provide stable and reliable power supply for the left and right driving wheel motors, ensuring the continuity and stability of the entire transportation process.

[0087] Through the above structural design, the present disclosure realizes the precise latent positioning and automatic traction and handling of the mud crab breeding rack, greatly improving the handling efficiency and significantly reducing the manual handling cost. The precise real-time control and balance monitoring technology enables the breeding rack to remain stable during handling, preventing the mud crabs in the breeding rack from being disturbed or damaged due to violent shaking, effectively improving the breeding effect and survival rate, and facilitating real-time movement according to the planning requirements of different breeding areas of the mud crab breeding site at any time. For example, when the mud crab seedlings are cultured in the cultivation basket of the original breeding rack until they grow into strong adults and need to be transferred to other areas of the breeding site for cultivation, when the breeding site continues to cultivate new mud crab seedlings, there is no need to transfer the mud crab seedlings that have grown into strong adults to the breeding rack 1 of other sites by transferring the basket or moving the cultivation baskets one by one in the original cultivation basket. Thus, the time and labor consumption caused by the unnecessary one-by-one movement of the mud crab cultivation baskets are reduced, and the disturbance to the mud crabs is also reduced. When moved to a new breeding site, they are still in the original cultivation basket. Therefore, there is no need to adapt to a new breeding environment, and the situation of reduced cultivation rate caused by basket transfer is reduced. In addition, during the movement of the mud crab breeding rack 1, intelligence and automation are also realized. Only an instruction needs to be issued to the central control platform, and the PLC control module is controlled to start the corresponding multiple trolleys and move them to the location where the breeding rack to be moved is located for simultaneous movement.

[0088] As an example of the present disclosure, to realize the environmental perception and driving accuracy control on the handling path of the mud crab breeding rack, the trolley further includes a first lidar sensor 35 and a second lidar sensor 36; the first lidar sensor 35 is located at the front of the chassis frame 31, and the second lidar sensor 36 is located at the rear of the chassis frame 31; the first lidar sensor 35 and the second lidar sensor 36 are used for monitoring obstacles in the front and rear (such as people, frames or walls), and can also be used as an emergency braking trigger or an input source for assisted SLAM positioning. The first lidar sensor 35 scans forward of the trolley 3, and the second lidar sensor 36 scans backward of the trolley 3. Both use 360° or 270° laser scanning technology, actively emit laser beams outward during the trolley's travel, receive the reflected signals after actively emitting the laser beams, calculate the laser propagation time and intensity, and realize the precise measurement of the distance and azimuth of the obstacles. Based on this detection information, cooperate with the PLC control module to adjust the obstacle avoidance path or perform emergency braking control, so as to ensure the driving safety of the trolley during the process of towing the mud crab breeding rack. This configuration is particularly suitable for scenarios with complex space, dynamic obstacles (such as people coming and going) or dense frame areas in the breeding site, effectively preventing equipment damage or scattering of breeding products caused by collisions, and improving the operation reliability. It can be used for anti-collision protection and dynamic path adjustment, and can also output radar echo mapping information in the SLAM assisted navigation scenario.

[0089] As an example of the present disclosure, to improve the path tracking accuracy and autonomous positioning ability, the trolley further includes a first magnetic sensor 37 and a second magnetic sensor 38. The first magnetic sensor 37 is located at the front of the first battery module 40, and the second magnetic sensor 38 is located at the rear of the second battery module 41. The above magnetic sensors are all high-sensitivity Hall sensors or AMR magnetoresistive array sensors, which are respectively installed in the middle front and rear of the trolley. The ground is pre-laid with a magnetic navigation path (such as magnetic strips, magnetic nails or magnetic tapes), and the sensor identifies the path signal by sensing the change of magnetic flux. By comparing the changes in the magnetic field intensity sensed on the left and right sides, it can be determined whether the trolley is currently deviating from the magnetic navigation path, and the feedback is given to the control module for deviation correction processing, so that the trolley always runs along the set path. At the same time, a characteristic magnetic field (such as a magnetic marker with different intensities or polarity changes) is set at the cross or path bifurcation points in the aquaculture workshop. The trolley can complete point position identification based on the sensor signal and accurately execute operations such as steering, docking, and turning. This magnetic navigation method does not require visual recognition, signal base stations or satellite positioning, and is suitable for working conditions such as high humidity, easy reflection or positioning occlusion in the aquaculture environment, and has the significant advantages of low cost, strong anti-interference, and simple deployment and maintenance.

[0090] To cooperate with the latent handling structure of the trolley, Figure 1 As shown, a roller 2 is respectively provided at the four bottom vertices of the mud crab breeding rack 1. By providing four rollers 2, the mud crab breeding rack 1 can slide freely on the ground. After receiving the control instruction from the PLC control module, the trolley drives along the magnetic navigation path and drives into the lower part of the mud crab breeding rack. After mechanical connection with the breeding rack through a bottom docking structure (such as a lifting docking pin, a hook, etc.), the left and right drive wheels are driven to drive the whole breeding rack to move to the target position. The roller structure greatly reduces the movement resistance of the breeding rack during transportation, avoids power loss or frame jamming caused by excessive bottom friction, is conducive to stable traction, and can improve the moving efficiency during multi-rack linkage handling. It is particularly suitable for working environments such as seafood aquaculture with heavy weight, heavy water vapor, and contact with wet and slippery ground, and improves the transportation convenience and operation efficiency of aquaculture equipment in complex terrains such as workshops, cold storages, and docks.

[0091] By using lidar to achieve front and rear obstacle perception, using magnetic sensors to complete path recognition and positioning control, and using the roller structure at the bottom of the breeding rack to achieve low-friction sliding handling, the latent mobile trolley provided by the present invention has the comprehensive technical advantages of high precision, high safety and high adaptability, and is particularly suitable for aquaculture handling scenarios such as mud crab aquaculture, meeting the intelligent aquaculture transportation requirements.

[0092] As another example of the present invention, a control method applied to the trolley as described above includes the following steps:

[0093] Initial positioning is performed to determine the initial pose of the trolley and obtain the magnetic navigation path, and the surrounding environment information is acquired to establish an initial map. The initial pose is determined by detecting magnetic strips or magnetic nails laid on the ground using the first magnetic sensor 37 and the second magnetic sensor 38, and the magnetic navigation path is obtained after magnetic flux change induction. The acquisition of the surrounding environment information is completed by the first lidar sensor 35 and the second lidar sensor 36.

[0094] Path tracking: Control the trolley to move along the magnetic navigation path, and in real time feedback the magnetic deviation information to the PLC control module 39 to adjust the left drive wheel side rotation angle δ L and the right drive wheel side rotation angle δ R of the trolley, so that the centroid of the trolley always coincides with the path point on the magnetic navigation path, and gradually approach the mud crab cultivation rack 1 to be moved according to the magnetic navigation path.

[0095] After reaching the docking point where the mud crab cultivation rack 1 contacts the trolley 3, the trolley 3 will engage the mud crab cultivation rack 1 to be moved with its own chassis frame 31.

[0096] The trolley transports the mud crab cultivation rack 1 to the target position according to the navigation path of the PLC control module 39 by optimizing the wheel speed and maintaining the frame load balance.

[0097] During transportation, the lidar scans the obstacles in front and behind in real time. When approaching abnormally, it decelerates or stops automatically, triggering the safety protection mechanism to avoid the risk of collision.

[0098] The real-time optimal control of the left and right wheel speeds of the trolley is the core to ensure transportation safety and path stability. Since the mud crab cultivation rack 1 has a certain weight and the load distribution may be uneven, if the left and right drive wheel speeds are not dynamically adjusted, it is very easy to cause the center of gravity to shift during the operation of the trolley, thus triggering risks such as steering errors, tire side slip, and even overturning. As an example of the present disclosure, during the process of transporting the mud crab cultivation rack 1 to the target position, it includes:

[0099] S1: Real-time obtain the longitudinal speed V of the left drive wheel x,L 、the longitudinal speed V of the right drive wheel x,R 、the lateral speed V of the left drive wheel y,L and the lateral speed V of the right drive wheel y,R , the angular velocity ω of the left drive wheel L and the angular velocity ω of the right drive wheel R ;

[0100] Figure 6 shows the force decomposition situation, the sideslip angle and the steering angle when the left drive wheel 33 and the right drive wheel 34 are asymmetrically stressed during the driving process of the trolley. Figure 6 In it, OXY is the earth coordinate system of the ground where the trolley travels.Figure 7 is Figure 6 an enlarged view of a partial area of, V L and V R are respectively the formal velocity vectors of the left and right drive wheels, V L is composed of the longitudinal velocity V x,L of the left drive wheel and the lateral velocity V y,L of the left drive wheel, V R is composed of the longitudinal velocity V x,R of the right drive wheel and the lateral velocity V y,R of the right drive wheel. Figure 7 In, α L , α R are respectively the sideslip angles of the left drive wheel 33 and the right drive wheel 34, and the magnitudes of the two will affect the lateral driving forces F y,L , F y,R of each drive wheel (when α i exists, the tire will generate an F y,i towards the outside to offset the skidding tendency), and the larger the sideslip angle, the more serious the tire skidding, which is likely to cause vehicle instability; δ L , δ R are the steering angles of the left drive wheel 33 and the right drive wheel 34, representing the physical deflection angles of the tires relative to the longitudinal direction of the vehicle body;

[0101] S2: Calculate the dynamic sideslip angles of the left drive wheel and the right drive wheel, and the slip ratios of the left drive wheel and the right drive wheel according to the real-time acquired data;

[0102] S3: Calculate the real-time lateral forces of the left drive wheel and the right drive wheel, and the real-time longitudinal forces of the left drive wheel and the right drive wheel;

[0103] S4: Use the lateral forces calculated in step S3 for real-time dynamic control of the trolley, construct a solution model for the optimal real-time rotational speeds of the left drive wheel and the right drive wheel, dynamically optimize the real-time rotational speeds of the left and right drive wheels, and achieve the driving with the vehicle center of gravity always maintaining a balanced state.

[0104] The S2 step includes:

[0105] S21: Construct a differential equation for the dynamic sideslip angle of the left drive wheel:

[0106]

[0107] Construct a differential equation for the dynamic sideslip angle of the right drive wheel

[0108]

[0109] where σ is the relaxation length of the tire sideslip angle; α L , α RThey are the dynamic sideslip angles of the left and right driving wheels respectively, and both are unknowns to be solved for. They are the real-time change rates of the sideslip angles of the left and right driving wheels respectively. Both are the derivatives of the unknowns to be solved for with respect to relative time, that is, the real-time change rates.

[0110] S22: Solve the differential equation constructed in step S21 using a discrete numerical method to obtain the dynamic sideslip angle α of the left driving wheel L and the dynamic sideslip angle α of the right driving wheel R ;

[0111] The discrete numerical method adopted can be solved using Euler integration method, backward difference method or explicit two-step method.

[0112] S23: Calculate the slip ratio λ of the left driving wheel L and the slip ratio λ of the right driving wheel R :

[0113]

[0114] where r w is the tire radius of the left driving wheel (33) and the right driving wheel (34) of the vehicle; ω L is the rotational angular velocity of the left driving wheel, and ω R is the rotational angular velocity of the right driving wheel; max(a, b) is a function that takes the larger value of a and b.

[0115] The formulas for calculating the real-time lateral force of the left driving wheel and the real-time lateral force of the right driving wheel in step S3 are as follows:

[0116] F y,i = D y sin[C y arctan((1 - E y )B y α [[ID=...]] i + F y arctan(B y α i ))];

[0117] where i = L or R, Figure 7 shows that when i = L, F y,L is the real-time lateral force of the left driving wheel; when i = R, F y,R is the real-time lateral force of the right driving wheel; D y is the amplitude of the lateral force of the driving wheel, D y = -3960; C y is the lateral force curvature factor, which controls the shape of the path curve caused by the sideslip due to the lateral force when the left and right driving wheels are moving. C y It should be noted that the original text seems to be incomplete at the end. If you have the full and correct text, it is recommended to provide it for a more accurate translation.= 1.1930; E y is the lateral force curvature adjustment factor, which controls the influence of the lateral deviation caused by the lateral force during the running of the left and right drive wheels on the curvature of the running path curve, E y = -1.0030; B y is the lateral force stiffness factor, which controls the sensitivity of the lateral force calculation model to α i , B y = -9.9389;

[0118] The formulas for calculating the real-time longitudinal force of the left drive wheel and the real-time longitudinal force of the right drive wheel are as follows:

[0119] F x,i = D x ·sin[C x ·arctan(B x λ i - E x (B x λ i - arctan(B x λ i )))];

[0120] Wherein, Figure 7 shows that when i = L, F x,L is the real-time longitudinal force of the left drive wheel; when i = R, F x,R is the real-time longitudinal force of the right drive wheel;; D x is the longitudinal force amplitude of the drive wheel, D x = 98.1; C x is the longitudinal force curvature factor, which controls the shape of the running path curve caused by the slip of the longitudinal force during the running of the left and right drive wheels, C x = 1.1800; E x is the longitudinal force curvature adjustment factor, which controls the influence of the slip caused by the lateral force during the running of the left and right drive wheels on the curvature of the running path curve, E x = -0.8024; B x is the longitudinal force stiffness factor, which controls the response degree (i.e., sensitivity) of the longitudinal force calculation model to λ i , B x = -7.7911.

[0121] During the running of the latent mobile trolley of the present disclosure, the lateral force F y,i directly depends on the sideslip angle α i , which is its main driving variable; however, in the case of strong traction or braking, the lateral grip of the tire will decrease, so the lateral force F y,i will be affected by the slip ratio λ i , so C y,i (λ i ) is used for Fy,i (α i ) performs slip coupling attenuation; similarly, the longitudinal force F x is determined by the slip ratio λ, but will be weakened by the sideslip angle α i during a sharp turn; therefore, G x,i (α i ) is used to perform sideslip attenuation modulation on F x,i (λ i ). That is, the lateral force (i.e., the side force) and the longitudinal force generated by the tire at the same contact point are coupled, and the two cannot reach their maximum values simultaneously. For example, when making a turn with a large sideslip angle, strong traction cannot be achieved. Therefore, G x,i (α i ) is used to adjust F x,i (λ i ), and G y,i (λ i ) is used to adjust F y,i (α i ).

[0122] The lateral force F y,i and the longitudinal force F x,i of the left and right driving wheels mentioned in this disclosure are the forces in the direction within their respective wheel body coordinate systems. When they need to be converted to the forces in the vehicle body coordinate system o v -x v y v (i.e., the coordinate system where the vehicle body is located), the forces of the left and right driving wheels in the x v axis direction of the vehicle body coordinate system can be obtained through the following transformation matrix The forces in the y v axis direction of the vehicle body coordinate system i = L or R. When i = L, it represents the left driving wheel, and when i = R, it represents the right driving wheel. Transformation matrix:

[0123] Figure 8 , Figure 9 respectively show the cross-influence of the slip ratio λ i and the sideslip angle α i on F x,i (λ i ), F y,i (α i ), Figure 8 shows that when the sideslip angle α i ≈0, the longitudinal force F x,i reaches the positive or negative peak. As λ i changes from negative value → 0 → positive value, F x,iGradually decrease from the positive maximum value to 0, and then further gradually decrease to the negative maximum value (i.e., its absolute value gradually increases, but it increases in the negative absolute value direction); when the sideslip angle α i moves along its axis away from the 0 point, that is, when the absolute value of |α i | increases, it will cause the influence factor G x,i (α i ) to affect the longitudinal force F x,i , resulting in F x,i being weakened (the value of F x,i decreases and gradually approaches the 0 value), that is, the larger the sideslip angle a i , the smaller the influence of the slip ratio λ i on the longitudinal force F x,i , indicating that severe sideslip will weaken the driving effect of the vehicle, and λ i exhibits typical slipping characteristics (decrease after the saturated force). Figure 9 In , when the slip ratio λ i ≈0, the lateral force F y,i reaches the positive or negative peak value. When λ i moves along its axis away from 0, that is, when the absolute value of |λ i | gradually increases, it will cause the influence factor G y,i (λ i ) to weaken and inhibit the lateral force F y,i ; while the sideslip angle α i mainly determines the lateral grip (i.e., the lateral force). When λ i ≈0, as α i changes from negative value → 0 → positive value, F y,i gradually increases. When λ i gradually moves away from 0, that is, when its absolute value gradually increases, as α i changes from negative value → 0 → positive value, F y,i fluctuates slightly near the 0 value. Figure 8 and Figure 9 respectively reflect the coupling change rules of the longitudinal / lateral forces of the tires with λ and α under different motion states such as straight-line acceleration, in-situ steering, turning, and load offset of the vehicle. Therefore, this model is applicable to all working conditions, has high generality and expandability, and is particularly suitable for the requirements of frequent starting, stopping, and turning during the handling of mud crabs.

[0124] The S4 step includes the following steps:

[0125] S41: The solution model for the real-time rotational speeds of the optimal left drive wheel and the right drive wheel constructed is as follows:

[0126]

[0127] Among them, G y,L and G y,R are the lateral force slip influence factors of the left and right drive wheels respectively; G x,L and G x,R are the longitudinal force sideslip influence factors of the left and right drive wheels respectively; η y is the lateral force difference weight coefficient, and η x is the longitudinal force difference weight coefficient; ω L,min and ω L,max are the minimum and maximum thresholds of the real-time rotational speed of the left drive wheel respectively; ω R,min and ω R,max are the minimum and maximum thresholds of the real-time rotational speed of the right drive wheel respectively; α L,min and α L,max are the minimum and maximum thresholds of the sideslip angle of the left drive wheel respectively; α R,min and α R,max are the minimum and maximum thresholds of the sideslip angle of the right drive wheel respectively; λ L,min and λ L,max are the minimum and maximum thresholds of the slip ratio of the left drive wheel respectively; λ R,min and λ R,max are the minimum and maximum thresholds of the slip ratio of the right drive wheel respectively; l L and l R are the lateral vertical distances from the left and right drive wheels to the center of gravity of the trolley respectively;

[0128] The slip ratio is an important parameter describing the longitudinal sliding degree of the wheel and is often used in vehicle dynamics and AGV control systems. It reflects the sliding phenomenon under the driving or braking state of the tire, that is, when the tire rotates, it does not roll completely on the road surface and will slip.

[0129] When braking, the actual rotational speed of the tire is less than its forward speed, and even a locked (sliding) phenomenon occurs, which is called negative slip or braking slip and is in a deceleration state; when λ i > 0, it is to control the slip of the left and right drive wheels; when λ i < 0, it is braking slip; when λ i = 0, it is pure rolling of the drive wheel without slip; the slip ratio λ i of the trolley is controlled within the range of ±10% is more ideal. When |λ i | > 0.2 (i.e., 20%), it indicates that the tire slips severely. The slip ratio is used to judge whether the tire slips, which helps to adjust the driving force in real time; judge the load state; adjust the speed difference between the left and right wheels to prevent deviation or slip; and achieve precise path tracking and speed control.

[0130] F y,L ·G y,L·l L = F y,R ·G y,R ·l R is the lateral force balance constraint condition, ensuring that the torque of the center of gravity of the trolley is 0, and avoiding eccentric load, tipping or unstable driving.

[0131] The first motor and the second motor that respectively drive the left drive wheel 33 and the right drive wheel 34 to rotate can both adopt the 1BLH450K-20FR driver, and its maximum rotational speed during continuous operation is 12 rad / s. Figure 10 Shows eight working conditions that will occur during the process of moving the mud crab breeding frame, namely straight forward, straight backward, right turn forward, right turn backward, left turn forward, left turn backward, clockwise rotation in place or counterclockwise rotation in place. Coupled with the situations of large acceleration, sharp turning or load deviation to one side during forward or backward movement, there are a total of twelve working conditions. The specific values of ω L,min , ω L,max , ω R,min , ω R,max under different working conditions are shown in Table 1, with the unit of rad / s.

[0132] Table 1

[0133]

[0134]

[0135] The specific values of α L,min , α L,max , α R,min , α R,max , λ L,min , λ L,max , λ R,min , λ R,max under different working conditions are shown in Table 2. The unit of α i is rad, and λ i is the slip ratio, which is essentially a ratio and has no unit.

[0136] Table 2

[0137]

[0138] During straight forward or straight backward movement, |α L | = |α R |, and the signs of α L and α R are the same, both being positive (i.e., the forward direction). At the same time, |λ L | = |λ R |; when turning right and moving forward or backward, |α L | > |α R | and |λ L|>|λ R |, and α L and α R have the same sign. When moving forward, they are both positive; when moving backward, they are both negative. When turning left and moving forward or backward, |α R |>|α L | and |λ R |>|λ L |, and α L and α R have the same sign. When moving forward, they are both positive; when moving backward, they are both negative. When rotating clockwise in place, |α L | = |α R |, and α L is positive, α R is negative. When rotating counterclockwise in place, |α L | = |α R |, and α L is negative, α R is positive.

[0139] η y and η x are roughly divided into 5 types according to different application scenarios. The values under different working conditions are shown in Table 3.

[0140] Table 3

[0141]

[0142] G y,L 、G y,R 、G x,L 、G x,R The calculation formulas are as follows:

[0143]

[0144] Among them, S H,x is the first horizontal displacement factor, which affects the horizontal offset adjustment effect of the sideslip angle α i of the left and right drive wheels and corrects the starting point position; S H,y is the second horizontal displacement factor, which corrects the lateral force of the left and right drive wheels and then corrects the initial slip ratio λ i ;

[0145]

[0146] Traditional control models only consider the static optimization of wheel speed or longitudinal force and lateral force (lateral force), ignoring the dynamic characteristics of the actual "effectiveness" of tire force changing with slip ratio and sideslip angle. This model introduces G y,L (λ L ), G y,R (λ R ) and Gx,L (α L ), G x,R (α R ), when the tire experiences side slip or driving wheel spin, etc., the contribution terms of the lateral force or the lateral force are dynamically weakened to prevent incorrect high-speed wheel speed output when the "theoretical force is very large" but the "actual grip ability is low". The optimization objective function of the model is to minimize the force difference between the left and right wheels. Through G y,L (λ L ), G y,R (λ R ) respectively perform coupled correction on F y,L and F y,R . F y,i ·G y,i is the actual lateral force. Similarly, F x,i ·G x,i is the actual driving force (longitudinal force). Therefore, the meaning of the constructed optimization model is that the smaller the force difference, the less the vehicle body center of gravity will shift. Especially in scenarios with large load changes such as towing a mud crab farming frame, the stability can be significantly improved. Compared with the existing wheel speed scheme based only on PID control, it is more robust. Furthermore, by introducing the coupling factors G x,i (α i ), G y,i (λ i ), the forces on the left and right driving wheels of the vehicle can be dynamically corrected. When the slip ratio or the side slip angle of the tire increases, resulting in a weakening of the grip ability of the corresponding driving wheel, the optimization model dynamically and automatically adjusts the rotational speeds ω L , ω R of the left and right driving wheels, reducing the target wheel speed, thereby realizing an adaptive dynamic adjustment strategy mechanism.

[0147] S42: Substitute the optimal real-time rotational speed ω L,best of the left driving wheel and the optimal real-time rotational speed ω R,best obtained in the S41 step into the S2 step, and solve for the lateral angles α i,best and the slip ratio λ i,best of the left and right driving wheels at this time, and further substitute them into the calculation formulas of the real-time lateral force of the left driving wheel and the real-time lateral force of the right driving wheel in the S3 step to obtain F y,i (α i,best ) and substitute them into the calculation formulas of the real-time longitudinal force of the left driving wheel and the real-time longitudinal force of the right driving wheel in the S3 step to obtain F x,i (λ i,best );

[0148] S43: Respectively judge whether the friction utilization rates μ i (λ i,best , α i,best ) of the left driving wheel and the right driving wheel are within their respective friction utilization threshold ranges:

[0149] Friction utilization rate μ i (λ i,best , α i,best ) is calculated as follows:

[0150]

[0151] The friction utilization threshold range is [0.70, 0.90];

[0152] If the friction utilization rates μ of the left drive wheel and the right drive wheel i (λ i,best , α i,best ) are both within the friction utilization threshold range, then output the optimal real-time rotational speed ω of the left drive wheel obtained by solving in step S41 L,best and the optimal real-time rotational speed ω of the right drive wheel R,best ; otherwise, repeat steps S41 - S43.

[0153] Figure 11 (a) shows the friction utilization rate μ of the left drive wheel L (λ L , α L ) and the co - variation relationship with the slip ratio λ of the left drive wheel L 、the side slip angle α of the left drive wheel L , reflecting the longitudinal force (i.e., traction force, driving force) F of the tire of the left drive wheel under different motion states x,L and the lateral force (i.e., lateral force, lateral adhesion) F y,L variation. Figure 11 (b) shows that when α L ≈0 (i.e., the side slip angle is small), μ L (λ L , α L ) first rises rapidly with the increase of |λ L |, reaches a peak when approaching about 1. When |λ L | exceeds the slip threshold of 0.25 (i.e., |λ L | > 0.25, that is, λ L > 0.25 or λ L < - 0.25), it enters the saturation zone or even decreases, showing typical slipping characteristics, indicating that the traction performance is the strongest at medium slip, and extremely high or extremely low slip both lead to a decrease in friction ability. Figure 11 (b) shows that when λ L ≈0 (i.e., pure rolling), μ L (λ L , α L ) also shows an upward trend with the increase of α L , indicating that at this time, the main factor affecting the friction utilization rate μ L (λ L , αL )'s lateral force, when |α L | exceeds 0.20 rad, μ L (λ L , α L ) gradually saturates, indicating that sideslip causes the tire grip to weaken and the control performance to decrease.

[0154] Figure 12 (a) shows the co-variation relationship of μ R (λ R , α R ) of the right driving wheel with the slip ratio λ L of the right driving wheel and the sideslip angle α L of the right driving wheel, reflecting the longitudinal force F x,R and lateral force F x,R changes of the tire of the right driving wheel under different motion states. Figure 12 (b)'s trend and Figure 12 (c)'s trend analysis is similar to Figure 11 (b) and Figure 11 (c), which will not be elaborated here. Figure 12 (b) shows that when α R ≈ 0, when |λ R | exceeds the slip threshold of 0.15, it enters the saturation zone; Figure 12 (c) shows that when λ R ≈ 0, when |α R | exceeds 0.20 rad, μ R (λ R , α R ) gradually saturates.

[0155] By collecting parameters such as the rotational speeds, longitudinal and lateral speeds of the left and right wheels in real time, combining with the dynamic sideslip angle and slip ratio, judging the friction utilization rate of the iterative results of the constructed optimized real-time rotational speed model of the left and right driving wheels, and optimizing the wheel speed with the goal of minimizing the difference between the longitudinal and lateral forces of the left and right wheels, it can not only effectively suppress the steering instability caused by load fluctuations, but also maintain the driving symmetry and running balance under dynamic conditions such as the car accelerating, decelerating, turning and avoiding obstacles. This optimized control strategy significantly improves the stability and reliability of the car under different path curvatures and load conditions, especially suitable for the breeding environment with complex paths or obvious changes in ground friction coefficients, effectively ensuring the safe handling and precise docking of the mud crab breeding frame.

[0156] Figure 13 shows the comparison diagram of the friction utilization rates of the left driving wheel and the right driving wheel with straight forward (①), straight backward (②), smooth left turn forward ③, smooth right turn forward ④, smooth left turn backward ⑤, smooth right turn backward ⑥, counterclockwise rotation in place (⑦) Spin CCW, clockwise rotation in place (⑧) as examples.

[0157] Figure 13 (a) shows the corresponding relationship between the friction utilization rate and the slip ratio of the left driving wheel in eight cases;

[0158] Figure 13 (b) shows the corresponding relationship between the friction utilization rate and the slip ratio of the right driving wheel in eight cases;

[0159] Figure 13 (c) shows the corresponding relationship between the friction utilization rate and the sideslip angle of the left driving wheel in eight cases;

[0160] Figure 13 (d) shows the corresponding relationship between the friction utilization rate and the sideslip angle of the right driving wheel in eight cases;

[0161] It can be seen from Figure 13 that when moving straight forward, the slip ratio λ of the left driving wheel L is about 0.05, and the sideslip angle α L is about 0.02 rad; the slip ratio λ of the right driving wheel R is about 0.05, and the sideslip angle α R is about 0.02 rad. The slip ratios of the two driving wheels are respectively in the region slightly to the positive direction in the middle of the friction utilization rate surface of Figure 11 (a), Figure 12 (a), with moderate utilization rate and safety.

[0162] When moving straight backward, the slip ratio λ of the left driving wheel L is about 0.05, and the sideslip angle α L is about 0.02 rad; the slip ratio λ of the right driving wheel R is about -0.05, and the sideslip angle α R is about -0.02 rad. The left driving wheel and the right driving wheel are symmetric about the vertical midline of the horizontal axis 0 point correspondingly in Figure 13 (a), Figure 13 (b), Figure 13 (c) and Figure 13 (d). At this time, the friction utilization rates of the left driving wheel and the right driving wheel are both relatively low, and there is no risk of rollover or center offset.

[0163] When moving forward steadily while turning left, the slip ratio λ of the left driving wheel L is about 0.02, and the sideslip angle α L is about 0.10 rad; the slip ratio λ of the right driving wheel R is about 0.06, and the sideslip angle α RIt is approximately 0.20 rad. At this time, the slip ratio and the sideslip angle of the right driving wheel are both larger than those of the left driving wheel. The friction utilization rate of the right driving wheel is higher, indicating that the right driving wheel, as the outer wheel, is subject to greater force, meeting the situation where the right driving wheel requires more driving force and the reaction force of friction with the ground to maintain the center of gravity balance when moving forward while turning left smoothly.

[0164] When moving forward while turning right smoothly, the slip ratio λ of the left driving wheel L is approximately 0.06, and the sideslip angle α L is approximately 0.20 rad; the slip ratio λ of the right driving wheel R is approximately 0.02, and the sideslip angle α R is approximately 0.10 rad. This situation is mirror-symmetrical to the case of moving forward while turning left smoothly. At this time, the left driving wheel, as the outer wheel, requires more driving force and the reaction force of friction with the ground. According to Figure 13 analysis, the friction utilization rate meets the requirements of this situation.

[0165] When moving backward while turning left smoothly, the slip ratio λ of the left driving wheel L is approximately -0.02, and the sideslip angle α L is approximately -0.10 rad; the slip ratio λ of the right driving wheel R is approximately -0.06, and the sideslip angle α R is approximately -0.20 rad. Compared with moving forward while turning left smoothly, both the left driving wheel and the right driving wheel need to reverse. However, since it is necessary to turn left, the absolute value of the force on the right driving wheel still needs to be greater than that of the left driving wheel.

[0166] When moving backward while turning right smoothly, the slip ratio λ of the left driving wheel L is approximately -0.06, and the sideslip angle α L is approximately -0.20 rad; the slip ratio λ of the right driving wheel R is approximately -0.02, and the sideslip angle α R is approximately -0.10 rad.

[0167] When rotating counterclockwise in place, the slip ratio λ of the left driving wheel L is approximately 0.10, and the sideslip angle α L is approximately 0.15 rad; the slip ratio λ of the right driving wheel R is approximately -0.10, and the sideslip angle α R is approximately -0.15 rad.

[0168] When rotating clockwise in place, the slip ratio λ of the left driving wheel L is approximately -0.10, and the sideslip angle α L is approximately -0.15 rad; the slip ratio λ of the right driving wheel R is approximately 0.10, and the sideslip angle α RIt is about 0.15 rad.

[0169] From Figure 13 As can be seen from the comparison shown, during the in-situ rotation process, through the method of the present disclosure, the rotational speeds of the left and right driving wheels output are optimized to make the friction utilization rates of the two wheels relatively high, ensuring that the slip ratios of the left and right driving wheels are consistent but in opposite directions, and the same is true for the sideslip angles, meeting the high sideslip angle and high slip ratio during in-situ rotation. Straight-line driving, turning, and reverse turning also meet the corresponding requirements. Through Figure 13 (a), Figure 13 the comparative analysis of the slip ratio and sideslip angle of the left driving wheel in (c), during the forward and reverse straight-line working conditions (λ L ≈ ±0.05), the value of μ L (λ L , α L ) is the lowest; when λ L is relatively large (such as in-situ rotation, outer wheel), the value of μ L (λ L , α L ) rises rapidly, indicating that the extreme states of the left driving wheel are in-situ rotation and the outer wheel during right turn. The overall variation range of the sideslip angle α L of the left driving wheel in different working conditions is from -0.2 rad to 0.2 rad, and the variation trend of μ L (λ L , α L ) with α L is similar to its variation trend with λ L , but is steeper, indicating that μ L (λ L , α L ) is more sensitive to the change of the sideslip angle α L . Therefore, through the present disclosure, by adjusting the wheel speeds of the left and right driving wheels, a high sideslip angle of the left driving wheel during forward right turn and in-situ clockwise rotation can be achieved.

[0170] Through Figure 13 (b), Figure 13 the comparative analysis of the slip ratio and sideslip angle of the right driving wheel in (d), the variation of μ R (λ R , α R ) with the slip ratio λ R is overall symmetric with the variation of μ L (λ L , α L ) of the left driving wheel with λ L . The method provided by the present disclosure controls the right driving wheel to have a relatively high λ R during left-turn movement or in-situ counterclockwise rotation, correspondingly increasing μ R (λ R , α R ). μR (λ R , α R ) varies with the slip ratio α R in the same way as that of the left driving wheel's μ L (λ L , α L ) varies with α L is overall symmetric in terms of the variation and trend. When the present disclosure controls the rotational speeds of the left and right driving wheels in the state of the outer left turning wheel (right driving wheel) or in-situ rotation, the value of μ R (λ R , α R ) reaches the maximum value.

[0171] When the latent vehicle bears a relatively large load on the frame (such as a mud crab incubator), the difference in load and lateral force on the left and right wheels will cause the overall center of gravity of the vehicle to shift and the movement to become unstable. Therefore, by constructing a dynamic model to optimize the real-time driving rotational speeds of the left and right wheels, the lateral forces on the left and right wheels are brought to dynamic balance, ensuring the vehicle runs stably and smoothly and avoiding tilting of the goods or shift of the center of gravity.

[0172] The above has described the embodiments of the present disclosure. The above description is exemplary and not exhaustive, and is not limited to the disclosed embodiments. Many modifications and variations are obvious to those of ordinary skill in the art in the technical field without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles of the embodiments, practical applications, or improvements to the technology in the market, or to enable other ordinary skill in the art in the technical field to understand the disclosed embodiments.

[0173] The above are only optional embodiments of the present disclosure and are not used to limit the present disclosure. For those skilled in the art, the present disclosure can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included within the protection scope of the present disclosure.

Claims

1. A latent mobile cart for a mud crab culture rack, the cart being used to move to the lower part of the mud crab culture rack (1) according to an instruction and tow the mud crab culture rack (1) to a desired position, characterized in that, The trolley (3) includes: A chassis frame (31); Trolley rollers (32) located at the four vertices of the bottom of the chassis frame; A left drive wheel (33) and a right drive wheel (34); A first motor (331) and a second motor (341), where the first motor (331) provides driving force for the left drive wheel (33); the second motor (341) provides driving force for the right drive wheel (34); A PLC control module (39) for controlling the forward and reverse rotations of the first motor (331) and the second motor (341), and for rotating the left drive wheel (33) and the right drive wheel (34) at the optimal real-time rotational speeds of the left drive wheel and the right drive wheel respectively; Two wheel speed encoders respectively used for real-time monitoring of the real-time rotational speeds of the left drive wheel (33) and the right drive wheel (34); Two longitudinal speed sensors respectively used for real-time monitoring of the longitudinal speeds of the left drive wheel (33) and the right drive wheel (34); Two lateral speed sensors respectively used for real-time monitoring of the lateral speeds of the left drive wheel (33) and the right drive wheel (34); Two power supply batteries respectively used for supplying power to the left drive wheel (33) and the right drive wheel (34).

2. The latent mobile trolley of the mud crab breeding rack according to claim 1, characterized in that, The trolley further includes a first lidar sensor (35) and a second lidar sensor (36) respectively used for scanning obstacles in front of and behind the trolley.

3. The latent mobile trolley of the mud crab breeding rack according to claim 1, characterized in that The trolley further includes a first magnetic sensor (37) and a second magnetic sensor (38) for identifying the magnetic navigation path, and for identifying whether the current pose of the trolley is centered or deviated from the specified target path and for point position identification at the crossroads.

4. The latent mobile trolley of the mud crab breeding rack according to claim 1, characterized in that One roller (2) is respectively arranged at the four vertices of the bottom of the mud crab breeding rack (1).

5. A control method applied to the trolley according to any one of claims 1-4, characterized in that It includes the following steps: Initial positioning, determining the initial pose of the trolley and obtaining the magnetic navigation path, and acquiring the surrounding environment information to establish an initial map; Path tracking, controlling the trolley to move along the magnetic navigation path, and real-time feedback of magnetic deviation information to the PLC control module (39), adjusting the lateral angles of the left drive wheel side and the right drive wheel side of the trolley, so that the centroid of the trolley always coincides with the path points on the magnetic navigation path, and gradually approaching the mud crab breeding rack (1) to be moved according to the magnetic navigation path; After reaching the docking point where the mud crab breeding rack (1) contacts the trolley (3), the trolley (3) clamps the mud crab breeding rack (1) to be moved with its own chassis frame (31); The trolley transports the mud crab breeding rack (1) to the target position according to the navigation path of the PLC control module (39) by optimizing the wheel speed and maintaining the balance of the frame load.

6. The control method according to claim 5, characterized in that During the process of transporting the mud crab breeding rack (1) to the target position, it includes: S1: Obtain the longitudinal speed V of the left drive wheel in real time x,L , the longitudinal speed V of the right drive wheel x,R , the lateral speed V of the left drive wheel y,L and the lateral speed V of the right drive wheel y,R , the angular velocity ω of the left drive wheel L and the angular velocity ω of the right drive wheel R ; S2: Calculating the dynamic lateral deviation angles of the left drive wheel and the right drive wheel, and the slip ratios of the left drive wheel and the right drive wheel according to the real-time acquired data; S3: Calculating the real-time lateral forces of the left drive wheel and the right drive wheel, and the real-time longitudinal forces of the left drive wheel and the right drive wheel; S4: Use the lateral force calculated in step S3 for real-time dynamic control of the trolley, construct a solution model for the real-time rotational speed of the optimal left drive wheel and the real-time rotational speed of the right drive wheel, dynamically optimize the real-time rotational speeds of the left and right drive wheels, and achieve the driving with the vehicle's center of gravity always maintaining a balanced state.

7. The control method according to claim 6, characterized in that, Step S2 includes: S21: Construct the differential equation of the dynamic slip angle of the left driving wheel: Construct the differential equation of the dynamic sideslip angle of the right driving wheel: where σ is the relaxation length of the tire sideslip angle; α L , α R are the dynamic sideslip angles of the left and right driving wheels respectively; are the real-time change rates of the sideslip angles of the left and right driving wheels respectively. S22: Solve the differential equation constructed in the step S21 by using a discrete numerical solution method, and obtain the dynamic side slip angle α of the left driving wheel L and the dynamic side slip angle α of the right driving wheel R ; S23: Calculate the slip ratio λ of the left driving wheel L and the slip ratio λ of the right driving wheel R : where r w is the tire radius of the left drive wheel (33) and the right drive wheel (34) of the trolley; ω L is the rotational angular velocity of the left drive wheel, and ω R is the rotational angular velocity of the right drive wheel; max(a, b) is a function that takes the larger value of a and b.

8. The control method according to claim 6, wherein In step S3, the formulas for calculating the real-time lateral force of the left drive wheel and the real-time lateral force of the right drive wheel are as follows: where i = L or R; D y is the amplitude of the driving wheel side force, D y = -3960; C y is the side force curvature factor, C y = 1.1930; E y is the side force curvature adjustment factor, E y = -1.0030; B y is the side force stiffness factor, which controls the sensitivity of the side force calculation model to α i B y = -9.9389; The formulas for calculating the real-time longitudinal force of the left drive wheel and the real-time longitudinal force of the right drive wheel are as follows: F x,i = D x · sin[C x · arctan(B x λ i - E x (B x λ i - arctan(B x λ i )))]; Among them,; D x is the longitudinal force amplitude of the driving wheel, D x = 98.1; C x is the longitudinal force curvature factor, C x = 1.1800; E x is the longitudinal force curvature adjustment factor, E x = -0.8024; B x is the longitudinal force stiffness factor B x = -7.7911.

9. The control method according to claim 8, characterized in that Step S4 includes the following steps: S41: The solution model for the real-time rotational speed of the optimal left drive wheel and the real-time rotational speed of the right drive wheel constructed is as follows: Among them, G y,L and G y,R are respectively the left drive wheel lateral force slip influence sub-factor and the right drive wheel lateral force slip influence sub-factor; G x,L and G x,R are respectively the left drive wheel longitudinal force sideslip influence factor and the right drive wheel longitudinal force sideslip influence factor; η y is the lateral force difference weight coefficient, and η x is the longitudinal force difference weight coefficient; ω L,min and ω L,max are respectively the minimum threshold and the maximum threshold of the real-time rotational speed of the left drive wheel; ω R,min and ω R,max are respectively the minimum threshold and the maximum threshold of the real-time rotational speed of the right drive wheel; α L,min and α L,max are respectively the minimum threshold and the maximum threshold of the left drive wheel sideslip angle; α R,min and α R,max are respectively the minimum threshold and the maximum threshold of the right drive wheel sideslip angle; λ L,min and λ L,max are respectively the minimum threshold and the maximum threshold of the left drive wheel slip ratio; λ R,min and λ R,max are respectively the minimum threshold and the maximum threshold of the right drive wheel slip ratio; l L and l R are respectively the lateral vertical distances from the left drive wheel and the right drive wheel to the center of gravity of the vehicle; S42: Substitute the optimal real-time rotational speed ω of the left driving wheel obtained by solving in step S41 L,best and the optimal real-time rotational speed ω of the right driving wheel R,best into step S2 to solve for the lateral angles α i,best of the left and right driving wheels and the slip ratio λ i,best , and further substitute them into the calculation formulas for the real-time lateral force of the left driving wheel and the real-time lateral force of the right driving wheel in step S3 to obtain F y,i (α i,best ) and substitute them into the calculation formulas for the real-time longitudinal force of the left driving wheel and the real-time longitudinal force of the right driving wheel in step S3 to obtain F x,i (λ i,best ); S43: Determine the friction utilization rates μ of the left and right drive wheels respectively i (λ i,best , α i,best ) are within their respective friction utilization thresholds: Friction utilization rate μ i (λ i,best , α i,best ) is calculated as follows: The friction utilization threshold range is [0.70, 0.90]; If the friction utilization rates μ of the left drive wheel and the right drive wheel i (λ i,best , α i,best ) are both within the friction utilization threshold range, then output the optimal real-time rotational speed ω L,best of the left drive wheel and the optimal real-time rotational speed ω R,best of the right drive wheel obtained by solving in step S41; otherwise, repeat steps S41 - S43.

10. The control method according to claim 9, characterized in that, G y,L 、G y,R 、G x,L 、G x,R The calculation formulas are as follows: Among them, S H,x is the first horizontal displacement factor, and S H,y is the second horizontal displacement factor;

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