Unmanned forklift control method, unmanned forklift and storage medium

Abstract

The invention relates to the technical field of handheld unmanned forklifts, and provides an unmanned forklift control method, an unmanned forklift and a storage medium. The unmanned forklift comprises a shell, a moving assembly, a lifting telescopic assembly and a flexible clamping assembly, the moving assembly is connected to the shell and used for driving the shell to move, the lifting telescopic assembly is connected to the shell, the flexible clamping assembly is connected to the lifting telescopic assembly, and the lifting telescopic assembly is used for driving the flexible clamping assembly to do lifting motion, namely telescopic motion. The flexible clamping assembly is used for clamping materials, and the clamping force of the flexible clamping assembly is adjustable.

Description

Technical Field

[0001] This application relates to the field of handheld unmanned forklift technology, and more particularly to unmanned forklift control methods, unmanned forklifts, and storage media. Background Technology

[0002] In existing technologies, a common control method for unmanned forklifts involves guiding a moving component, which then drives the forklift housing to a target area via a laser navigation system. Upon arrival, an operator remotely triggers the lifting and telescopic component to perform a clamping operation. This method typically incorporates basic interlocking logic, such as prohibiting lifting during movement to prevent mechanical interference. However, this method suffers from a major drawback: its control logic relies solely on a single state (e.g., whether it is moving) for simple interlocking, failing to perform multi-dimensional coupling and judgment of the clamping force of the flexible clamping component, the actual height of the lifting and telescopic component, and the overall dynamic stability of the forklift. This results in the forklift continuing to move at normal speed even when the clamping is insecure or the forklift is raised, potentially leading to material slippage or forklift rollover accidents. Therefore, a safety control method capable of achieving multi-parameter coordinated linkage is urgently needed. Summary of the Invention

[0003] This application aims to address at least one of the technical problems existing in the related art. To this end, this application proposes an unmanned forklift control method, an unmanned forklift, and a storage medium.

[0004] The unmanned forklift control method according to the first aspect of this application includes the following steps: Step S1: Obtain the current position information of the housing based on the laser navigation system, and compare the current position information with the position information of the preset target area to obtain the position deviation value; if the position deviation value is less than or equal to the preset position deviation threshold, and the speed of the moving component is continuously lower than the preset speed threshold for more than the preset stopping confirmation time, it is determined that the housing has stopped. Step S2: Based on the determination that the housing has stopped, send a lifting and lowering command to the programmable logic controller; based on the lifting and lowering command, control the lifting and telescopic components to perform lifting and telescopic movements until the flexible clamping components reach the preset working height and preset extension position; Step S3: Based on the arrival signal of the lifting and telescopic component reaching the preset working height and the preset extension position, send a clamping permission command to the programmable logic controller; based on the clamping permission command, control the flexible clamping component to perform clamping action, and obtain the clamping force value output by the flexible clamping component in real time; Step S4: Based on the comparison between the clamping force value and the preset clamping force threshold, a clamping state determination result is obtained; based on the clamping state determination result that the clamping force value is lower than the preset clamping force threshold by a preset first proportion, the moving component is controlled to reduce the driving speed from the normal driving speed to the preset low driving speed. Step S5: Based on the fact that the clamping force value is further lower than the preset second ratio of the preset clamping force threshold, control the moving component to stop running immediately and trigger the audible and visual alarm device to sound an alarm; Step S6: Based on the fact that the current lifting height of the lifting and telescopic component is greater than a preset height threshold, control the travel speed of the moving component to be limited to no more than a preset speed limit value, and prohibit the moving component from performing sharp turning operations with a steering angular velocity greater than a preset steering angular velocity threshold.

[0005] According to one embodiment of this application, the process of controlling the lifting and telescopic assembly to perform lifting and telescopic movements, and controlling the flexible clamping assembly to perform clamping actions, further includes the following steps: Step A1: Based on the real-time acquisition of the lifting displacement signal and the telescopic displacement signal by the magnetostrictive displacement sensor installed on the lifting and telescopic assembly, obtain the current actual position information of the lifting and telescopic assembly; Step A2: Compare the current actual position information with the preset target position information to obtain a position deviation signal; based on the position deviation signal, generate a position control output signal through an adaptive fuzzy PID controller; Step A3: Based on the output torque signal collected in real time by the torque sensor installed on the flexible clamping assembly, obtain the current actual clamping force information of the flexible clamping assembly; Step A4: Compare the current actual clamping force information with the preset clamping force command to obtain a clamping force deviation signal; generate a force feedforward compensation signal based on the clamping force deviation signal; Step A5: The position control output signal and the force feedforward compensation signal are superimposed to obtain a composite control signal; Step A6: Based on the composite control signal, synchronously adjust the output of the drive unit of the lifting and telescopic component and the output of the drive unit of the flexible clamping component so that the motion trajectory of the lifting and telescopic component is dynamically matched with the clamping force of the flexible clamping component.

[0006] According to one embodiment of this application, the process of controlling the flexible clamping assembly to perform a clamping action further includes the following steps: Step B1: Based on the comparison between the drive current signal of the flexible clamping component when it initially contacts the material and the preset no-load current reference value, the estimated weight of the material is obtained. Step B2: Based on the output torque signal continuously collected by the torque sensor of the flexible clamping component during the clamping process, the clamping force fluctuation value is calculated; Step B3: Based on the contact pressure data output by the pressure distribution sensor array integrated on the gripper surface of the flexible clamping component, the effective contact area between the gripper and the material is obtained; Step B4: Based on the estimated weight of the material and the effective contact area, and combined with the current extension length information of the lifting and telescopic component, obtain the offset of the material's center of gravity relative to the center of gravity of the flexible clamping component; Step B5: Based on the estimated material weight, the clamping force fluctuation value, the effective contact area, and the center of gravity offset, generate dynamic clamping force control parameters using a fuzzy PID controller; Step B6: Based on the dynamic clamping force control parameters, adjust the output torque of the left and right gripper drive units of the flexible clamping assembly so that the clamping torque on both sides is asymmetrically distributed according to the center of gravity offset, thereby achieving adaptive clamping torque distribution.

[0007] According to one embodiment of this application, the process of controlling the lifting and telescopic assembly to perform lifting and telescopic movements further includes the following steps: Step C1: Compare the current actual position information of the lifting and telescopic component with the preset target position information to obtain the total displacement; Step C2: Based on the total displacement and the preset maximum operating speed, determine that the motion process of the lifting and telescopic component includes three continuous stages: acceleration, constant speed, and deceleration. Step C3: Based on the preset maximum acceleration value and the preset jerk limit value, generate the velocity change curve of the acceleration segment and the velocity change curve of the deceleration segment, so that the velocity change process meets the S-curve smoothness requirements; Step C4: Based on the speed change curve of the acceleration segment, the constant speed value of the uniform speed segment, and the speed change curve of the deceleration segment, synthesize a complete S-curve speed planning trajectory; Step C5: Discretize the time based on the S-curve velocity planning trajectory to obtain the target velocity command sequence corresponding to each sampling time; Step C6: Based on the target speed command sequence, adjust the output of the drive unit of the lifting and telescopic component in real time so that the actual movement speed of the lifting and telescopic component tracks the S-curve speed planning trajectory.

[0008] According to one embodiment of this application, the unmanned forklift operation further includes the following steps: Step D1: Based on the force sensor installed on the flexible clamping assembly, the height sensor installed on the lifting and telescopic assembly, and the speed detection unit installed on the moving assembly, the clamping force signal, lifting height signal, and travel speed signal are collected in real time. Step D2: Based on the clamping force signal, compare it with a preset clamping safety threshold to obtain a first threshold judgment result; based on the lifting height signal, compare it with a preset height safety threshold to obtain a second threshold judgment result; based on the driving speed signal, compare it with a preset speed safety threshold to obtain a third threshold judgment result. Step D3: Based on the changing trend of the clamping force signal within a preset time window, calculate the clamping force change rate; based on the fact that the clamping force change rate is less than a preset negative change rate threshold, obtain the clamping loosening trend prediction result; Step D4: Based on the first threshold judgment result, the second threshold judgment result, the third threshold judgment result, and the clamping loosening trend prediction result, comprehensively determine the current safety risk level; Step D5: Based on the fact that the safety risk level is a primary risk level, control the mobile component to reduce its speed and activate a warning prompt; Step D6: Based on the fact that the safety risk level is high risk level, control the moving component to stop operating, lock the electromagnetic brake, and trigger the audible and visual alarm device to issue an emergency alarm.

[0009] According to a second aspect of this application, the unmanned forklift includes: case; A movable component, connected to the housing, is used to move the housing; A lifting and telescopic assembly is connected to the housing; A flexible clamping component is connected to the lifting and telescopic component. The lifting and telescopic component is used to drive the flexible clamping component to move up and down, i.e., to move forward and backward. The flexible clamping component is used to clamp materials, and the clamping force of the flexible clamping component is adjustable.

[0010] According to one embodiment of this application, the lifting and telescopic assembly includes a lifting drive and a telescopic drive. The lifting drive is connected to the housing, and the telescopic drive is connected to the lifting drive. The flexible clamping assembly is connected to the telescopic drive. The lifting drive is used to drive the telescopic drive to move up and down relative to the housing, and the telescopic drive is used to drive the flexible clamping assembly to move horizontally and telescopically relative to the housing.

[0011] According to one embodiment of this application, the flexible clamping assembly includes a clamping drive and a gripper, the clamping drive is connected to the gripper, and the clamping drive is used to drive the gripper to open and close so that the gripper can be used to clamp materials; The clamping force of the clamping drive can be infinitely adjusted between aN and bN, where b is greater than a.

[0012] An electronic device according to a third aspect of this application includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the unmanned forklift control method described above.

[0013] According to a fourth aspect of this application, a non-transitory computer-readable storage medium includes a computer program that, when executed by the processor, implements the unmanned forklift control method described above.

[0014] According to a fifth aspect of this application, the computer program product includes a computer program that, when executed by the processor, implements the unmanned forklift control method described above.

[0015] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments or related technologies of this application, the accompanying drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a flowchart of the unmanned forklift control method provided by the present invention; Figure 2 This is a structural schematic diagram of the unmanned forklift provided by the present invention; Figure 3 This is a partial structural schematic diagram of the unmanned forklift provided by the present invention; Figure 4 This is a schematic diagram of the structure of the flexible clamping assembly provided by the present invention; Figure 5 This is a schematic diagram of the structure of the electronic device provided by the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] This application provides an embodiment of an unmanned forklift control method. It should be noted that although the logical order is shown in the flowchart, under certain data conditions, the steps shown or described may be performed in a different order than that shown here.

[0020] Before introducing the unmanned forklift control method of the present application, the application scenarios of the unmanned forklift control method will be explained first. The unmanned forklift control method of the present application can be applied to smart terminals such as smartphones, tablets and computers, and can also be applied to servers. The present application does not make any special limitations here, as long as it can support and implement the unmanned forklift control method of the present application.

[0021] The following is combined with Figures 1 to 5 This application describes the unmanned forklift control method, the unmanned forklift, and the storage medium.

[0022] According to the embodiments of the first aspect of this application, such as Figure 1 , Figure 2 , Figure 3 and Figure 4 The unmanned forklift control method is applied to unmanned forklifts. In this embodiment, the unmanned forklift includes a housing, a moving component, a lifting and telescopic component, and a flexible clamping component. The moving component is connected to the housing and is used to move the housing. The lifting and telescopic component is connected to the housing, and the flexible clamping component is connected to the lifting and telescopic component. The lifting and telescopic component is used to drive the flexible clamping component to move up and down (i.e., telescopic movement). The flexible clamping component is used to clamp materials, and the clamping force of the flexible clamping component is adjustable.

[0023] The unmanned forklift control method includes the following steps: Step S1: Obtain the current position information of the housing based on the laser navigation system, and compare the current position information with the position information of the preset target area to obtain the position deviation value; if the position deviation value is less than or equal to the preset position deviation threshold, and the speed of the moving component is continuously lower than the preset speed threshold for more than the preset stopping confirmation time, it is determined that the housing has stopped. The programmable logic controller (PLC) acquires the current position information of the housing in real time through the laser navigation system and compares it with the position information of the preset target area specified in the task to calculate the position deviation value. Simultaneously, it acquires the current speed of the moving component through a speed detection unit (such as a wheel hub encoder or IMU). When the position deviation value is less than or equal to a preset position deviation threshold, and the speed of the moving component remains below the preset speed threshold for more than a preset stopping confirmation time, the PLC determines that the housing has come to a stop.

[0024] In one specific implementation, the preset position deviation threshold can be 50 mm, the preset speed threshold can be 0.05 m / s, and the preset stopping confirmation time can be 0.5 seconds. Furthermore, the closed state of the electromagnetic brake can be used as an auxiliary criterion to improve the reliability of the stopping determination.

[0025] Step S2: Based on the determination that the housing has stopped, send a lifting and lowering command to the programmable logic controller; based on the lifting and lowering command, control the lifting and telescopic components to perform lifting and telescopic movements until the flexible clamping components reach the preset working height and preset extension position; Based on the determination that the housing has stabilized, the programmable logic controller (PLC) generates a lifting / retracting command and sends it to the drive unit of the lifting / retracting assembly. In response to this command, the lifting / retracting assembly begins lifting and extending movements until the flexible clamping assembly reaches the preset working height and preset extension position. The positioning status is detected by a displacement sensor or encoder mounted on the lifting / retracting assembly, which then sends a positioning signal back to the PLC.

[0026] For example, the preset working height can be set to 2.3 meters based on the shelf height, and the preset extension position can be set to 1.2 meters based on the pallet depth. However, these values ​​are just examples and can be flexibly configured according to the actual working scenario.

[0027] Step S3: Based on the arrival signal of the lifting and telescopic component reaching the preset working height and preset extension position, send a clamping permission command to the programmable logic controller; based on the clamping permission command, control the flexible clamping component to perform clamping action, and obtain the clamping force value output by the flexible clamping component in real time; Upon receiving a signal indicating that the lifting and telescopic assembly has reached the preset working height and preset extension position, the programmable logic controller (PLC) sends a clamping permission command to the flexible clamping assembly. The flexible clamping assembly responds to the command by executing the clamping action, while its built-in clamping force sensor collects and outputs the clamping force value in real time for continuous monitoring by the PLC.

[0028] The preset clamping force threshold can be pre-calibrated based on the material weight, surface friction coefficient, and safety margin. In a preferred embodiment, this threshold can be set to 500 Newtons to ensure that the pallet does not slip during handling.

[0029] Step S4: Based on the comparison between the clamping force value and the preset clamping force threshold, obtain the clamping state determination result; based on the clamping state determination result that the clamping force value is lower than the preset clamping force threshold by a preset first proportion, control the moving component to reduce the driving speed from the normal driving speed to the preset low driving speed. The programmable logic controller (PLC) compares the real-time clamping force value with a preset clamping force threshold. If the clamping force value is lower than a preset first ratio of the preset clamping force threshold, it determines that there is a risk of loosening in the clamping state, and accordingly controls the moving component to reduce the driving speed from the normal driving speed to a preset low driving speed.

[0030] For example, the preset first ratio can be set to 90%, the normal travel speed can be 5 km / h, and the preset low-speed travel speed can be 1 km / h. This speed reduction strategy can reduce the risk of material falling due to insecure clamping while ensuring the continuity of operations.

[0031] Step S5: Based on the fact that the clamping force value is further lower than the preset second ratio of the preset clamping force threshold, control the moving component to stop running immediately and trigger the audible and visual alarm device to sound an alarm; If the clamping force value further decreases and falls below the preset second ratio of the preset clamping force threshold, the programmable logic controller immediately controls the moving component to stop operating, cuts off the drive power supply and activates the electromagnetic brake to lock the wheel, triggers the audible and visual alarm device to issue an alarm, and can upload fault information to the central dispatch system.

[0032] In one specific implementation, the preset second ratio can be set to 80%. This mechanism constitutes the last line of defense to prevent safety accidents caused by severe clamping failure.

[0033] Step S6: Based on the fact that the current lifting height of the telescopic component is greater than the preset height threshold, control the travel speed of the moving component to be limited to no more than the preset speed limit value, and prohibit the moving component from performing sharp turning operations with a steering angular velocity greater than the preset steering angular velocity threshold. Throughout the operation, the programmable logic controller continuously reads the current lifting and telescopic component's height. When this height exceeds a preset height threshold, it automatically imposes restrictions on the movement of the mobile component: on the one hand, it limits the maximum permissible speed to no more than a preset speed limit; on the other hand, it prohibits sharp turns with a steering angular velocity greater than a preset steering angular velocity threshold, in order to suppress rollover torque under high center of gravity conditions.

[0034] For example, the preset height threshold can be set to 2 meters, the preset speed limit can be set to 2 kilometers per hour, and the preset steering angular velocity threshold can be set to 15 degrees per second. These parameters can be dynamically adjusted according to the forklift's structural parameters (such as wheelbase and weight) and load characteristics, and can even be adaptively set based on a real-time center of gravity model.

[0035] According to the unmanned forklift control method of this application embodiment, based on the determination result that the housing has stopped in step S1, based on the determination result, in step S2, a lifting permission command is sent to the programmable logic controller, and the lifting and telescopic component is controlled to move to a preset working height and a preset extension position. Based on the arrival signal of the lifting and telescopic component reaching the preset working height and the preset extension position, in step S3, a clamping permission command is sent to the programmable logic controller, and the clamping force value output by the flexible clamping component is acquired in real time. Based on the comparison between the clamping force value and the preset clamping force threshold, a clamping state determination result is obtained in step S4. When the clamping force value is lower than a preset first proportion of the preset clamping force threshold, the moving component is controlled to reduce the travel speed to a preset low travel speed. Based on the clamping force value being further lower than a preset second proportion of the preset clamping force threshold, in step S... 5. The control unit immediately stops operation and triggers the audible and visual alarm device. At the same time, based on the fact that the current lifting height of the lifting and telescopic component is greater than the preset height threshold, in step S6, the travel speed of the moving component is controlled to not exceed the preset speed limit and sharp turning operations are prohibited. Through the multi-parameter coordinated linkage of the above six steps—using the stationary state, clamping force, and lifting height as dynamic criteria for driving permission, speed adjustment, and turning restriction, respectively, and establishing a graded response mechanism (speed reduction → shutdown → height and turning limit), the system realizes real-time closed-loop control of clamping reliability and overall vehicle stability. This effectively solves the safety accidents caused by material slippage or forklift rollover in the background technology, which is caused by relying solely on simple interlocking based on a single movement state, even when the clamping is not secure or the vehicle is still traveling at normal speed in a high-lift state. This achieves inherently safe operation of unmanned forklifts in complex operating scenarios.

[0036] In some embodiments, the process of controlling the lifting and telescopic assembly to perform lifting and telescopic movements, and controlling the flexible clamping assembly to perform clamping actions, further includes the following steps: Step A1: Based on the real-time acquisition of the lifting displacement signal and the telescopic displacement signal by the magnetostrictive displacement sensor installed on the lifting and telescopic assembly, obtain the current actual position information of the lifting and telescopic assembly; The programmable logic controller (PLC) acquires two analog signals in real time via a magnetostrictive displacement sensor mounted on the lifting and telescopic assembly: one signal reflects the extension length of the lifting cylinder piston rod, and the other reflects the extension length of the telescopic arm. The controller converts these two signals into millimeter values, resulting in a lifting displacement signal of 2300 mm and a telescopic displacement signal of 1200 mm. From this, the PLC obtains the current actual position information of the lifting and telescopic assembly. Here, "current actual position information" refers to the two-dimensional position state composed of the lifting height and the telescopic length.

[0037] Step A2: Compare the current actual position information with the preset target position information to obtain the position deviation signal; based on the position deviation signal, generate the position control output signal through an adaptive fuzzy PID controller; The programmable logic controller (PLC) calls the preset target position information from the task, such as a preset working height of 2300 mm and a preset extension position of 1200 mm. The controller subtracts the preset target position information from the current actual position information obtained in step A1, resulting in a position deviation signal of 0 mm in both the lifting and extending directions. Subsequently, the controller inputs these two deviation signals to an adaptive fuzzy PID controller. This controller dynamically adjusts the proportional coefficient, integral time, and derivative time based on the magnitude and rate of change of the deviation, generating a voltage signal to drive the hydraulic proportional valve, i.e., the position control output signal. Here, the "adaptive fuzzy PID controller" refers to a deterministic controller that automatically adjusts control parameters based on deviation characteristics; its rule base is pre-installed in the program and does not rely on online learning.

[0038] Step A3: Based on the output torque signal collected in real time by the torque sensor installed on the flexible clamping component, obtain the current actual clamping force information of the flexible clamping component; The programmable logic controller (PLC) acquires the output torque signal in real time via a torque sensor mounted on the output shaft of the drive motor of the flexible clamping assembly. This signal is calibrated and converted into clamping force units, yielding the current actual clamping force information of 480 Newtons. Here, "current actual clamping force information" refers to the equivalent clamping force currently applied to the material by the flexible clamping assembly.

[0039] Step A4: Compare the current actual clamping force information with the preset clamping force command to obtain the clamping force deviation signal; generate a force feedforward compensation signal based on the clamping force deviation signal; The programmable logic controller (PLC) reads the preset clamping force command set in the current task, for example, 500 Newtons. The controller calculates the difference between the current actual clamping force information of 480 Newtons obtained in step A3 and the command, resulting in a clamping force deviation signal of -20 Newtons. Based on this deviation signal, the controller generates a force feedforward compensation signal with a value of -16 Newtons by looking up a table or using a preset formula (e.g., compensation amount = deviation × 0.8). This signal is used to compensate for insufficient clamping force in advance, preventing clamping failure due to system lag.

[0040] Step A5: The position control output signal and the force feedforward compensation signal are superimposed to obtain the composite control signal; The programmable logic controller (PLC) algebraically superimposes the position control output signal (e.g., +5.0 volts) generated in step A2 with the force feedforward compensation signal (-16 Newtons, converted to an equivalent voltage of -0.3 volts) generated in step A4 to obtain a composite control signal of +4.7 volts. Here, "superposition" refers to the linear synthesis of two signals with different physical meanings but belonging to the same control domain at the drive command level to achieve coupled control of position and force.

[0041] Step A6: Based on the composite control signal, synchronously adjust the output of the drive unit of the lifting and telescopic component and the output of the drive unit of the flexible clamping component so that the motion trajectory of the lifting and telescopic component and the clamping force of the flexible clamping component are dynamically matched. The programmable logic controller (PLC) maps the composite control signal obtained in step A5 to the hydraulic proportional valve control port of the lifting and telescopic assembly and the servo motor driver input port of the flexible clamping assembly, respectively. For the lifting and telescopic assembly, this signal adjusts the hydraulic flow to fine-tune the lifting speed; for the flexible clamping assembly, this signal adjusts the motor current to enhance the clamping force. The synchronous response of both ensures that if a slight decrease in clamping force is detected during lifting, the system automatically slows down the lifting speed and instantaneously increases the force, thereby ensuring a dynamic match between clamping stability and motion smoothness.

[0042] Understandably, based on the real-time acquisition of lifting and telescopic displacement signals from the magnetostrictive displacement sensor installed on the lifting and telescopic assembly, the current actual position information of the lifting and telescopic assembly is obtained in step A1. Based on the current actual position information and the preset target position information, a position deviation signal is obtained in step A2, and a position control output signal is generated through an adaptive fuzzy PID controller. Based on the real-time acquisition of the output torque signal from the torque sensor installed on the flexible clamping assembly, the current actual clamping force information of the flexible clamping assembly is obtained in step A3. Based on the current actual clamping force information and the preset clamping force command, a clamping force deviation signal is obtained in step A4, and a force feedforward compensation signal is generated. Based on the position control output signal and the force feedforward compensation signal, the position deviation signal is generated. The compensation signal is superimposed in step A5 to obtain a composite control signal. Finally, based on the composite control signal, the output of the drive unit of the lifting and telescopic component and the output of the drive unit of the flexible clamping component are synchronously adjusted in step A6. Through the coordinated execution of the above six steps, the programmable logic controller realizes the dynamic coupling of the position control loop and the clamping force control loop. Without introducing a complex model, the lifting motion and the clamping force form a closed-loop linkage that compensates for each other. This effectively solves the problem of clamping force fluctuation caused by load disturbance or mechanical compliance during the lifting process, thereby ensuring the reliability of clamping and the stability of operation under high lifting or telescopic conditions, and providing underlying execution accuracy support for the multi-dimensional safety control in claim 1.

[0043] In some embodiments, the process of controlling the flexible clamping assembly to perform clamping actions further includes the following steps: Step B1: Based on the comparison between the drive current signal of the flexible clamping component when it initially contacts the material and the preset no-load current reference value, the estimated weight of the material is obtained. The programmable logic controller (PLC) monitors the drive current signal of the flexible gripping component's drive motor at the moment the grippers initially contact the material, recording the current value as 8.5 amps. The system has a pre-defined no-load current baseline value of 2.0 amps obtained through no-load operation calibration. The controller calculates the difference between the two as 6.5 amps and, based on a pre-established current-load mapping table (e.g., each 1 amp increment corresponds to approximately 15 kg of material weight), estimates the material weight to be 97.5 kg. Here, the "estimated material weight" refers to the approximate mass of the gripped material calculated based on the increase in drive current.

[0044] Step B2: The torque sensor based on the flexible clamping component continuously collects the output torque signal during the clamping process, and calculates the clamping force fluctuation value; The programmable logic controller (PLC) continuously reads the torque signal output from the torque sensor mounted on the drive shaft of the flexible clamping assembly, collecting 100 sample points within one second after clamping stabilizes. The controller identifies the maximum value as 520 N·m and the minimum value as 480 N·m, calculating the difference between them as 40 N·m. This value is the clamping force fluctuation value. Here, the "clamping force fluctuation value" refers to the peak-to-peak value of the torque signal during clamping, used to characterize clamping stability.

[0045] Step B3: Based on the contact pressure data output by the pressure distribution sensor array integrated on the surface of the gripper of the flexible clamping component, the effective contact area between the gripper and the material is obtained; The programmable logic controller (PLC) receives data from an array of pressure distribution sensors integrated on the surfaces of the left and right grippers of the flexible clamping assembly. This array consists of 20 miniature pressure-sensitive units on each side. The controller counts the number of pressure-sensitive units whose output pressure exceeds a preset contact threshold (e.g., 1 kPa), totaling 32. Each unit has an effective sensing area of ​​25 square millimeters, therefore the effective contact area is 32 × 25 = 800 square millimeters. Here, "effective contact area" refers to the total area of ​​actual effective pressure contact between the grippers and the material.

[0046] Step B4: Based on the estimated material weight and effective contact area, combined with the current extension length information of the lifting and telescopic component, obtain the offset of the material's center of gravity relative to the center of gravity of the flexible clamping component. The programmable logic controller (PLC) retrieves the current extension length information of the lifting and telescopic assembly, for example, 1.2 meters. Combining the estimated material weight of 97.5 kg obtained in step B1 and the effective contact area of ​​800 square millimeters obtained in step B3, it uses a pre-stored mechanical model (simplified to a cantilever beam force model) to calculate the horizontal offset distance of the material's center of gravity relative to the center of the flexible clamping assembly's jaws. Assuming the material is an asymmetrical pallet, the calculated center of gravity offset is +80 millimeters (the positive sign indicates the center of gravity is biased towards the right jaw). Here, "center of gravity offset" refers to the lateral offset distance of the material's center of gravity relative to the clamping center within the jaw plane, in millimeters.

[0047] Step B5: Based on the estimated material weight, clamping force fluctuation, effective contact area, and center of gravity offset, generate dynamic clamping force control parameters using a fuzzy PID controller; The programmable logic controller (PLC) inputs the estimated material weight of 97.5 kg from step B1, the clamping force fluctuation of 40 N·m from step B2, the effective contact area of ​​800 mm² from step B3, and the center of gravity offset of +80 mm from step B4 into a fuzzy PID controller. This controller incorporates multiple rules, such as: "If the center of gravity offset is large and the effective contact area is small, significantly increase the clamping torque on the right side"; "If the clamping force fluctuation is high, increase the integral gain to suppress oscillations." After fuzzy inference and defuzzification, the controller outputs a set of dynamic clamping force control parameters, including a target torque of 450 N·m on the left and a target torque of 550 N·m on the right.

[0048] Step B6: Based on the dynamic clamping force control parameters, adjust the output torque of the left and right gripper drive units of the flexible clamping component so that the clamping torque on both sides is asymmetrically distributed according to the center of gravity offset, thereby achieving adaptive clamping torque distribution. The programmable logic controller (PLC) sends the dynamic clamping force control parameters generated in step B5 to the left and right gripper drive units of the flexible clamping assembly. The left drive unit adjusts its servo motor output torque to 450 N·m, and the right drive unit adjusts it to 550 N·m, forming an asymmetrical torque distribution. Because the material's center of gravity is biased to the right, the right side provides a larger clamping torque to balance the overturning torque, thereby achieving an adaptive clamping torque distribution and preventing the material from rotating or slipping during handling.

[0049] Understandably, based on the drive current signal of the flexible clamping component when it initially contacts the material and the preset no-load current reference value, the estimated material weight is obtained in step B1. Based on the output torque signal continuously collected by the torque sensor of the flexible clamping component during clamping, the clamping force fluctuation value is calculated in step B2. Based on the contact pressure data output by the pressure distribution sensor array integrated on the gripper surface of the flexible clamping component, the effective contact area between the gripper and the material is obtained in step B3. Based on the estimated material weight, the effective contact area, and the current extension length information of the lifting and telescopic component, the offset of the material's center of gravity relative to the flexible clamping component is obtained in step B4. Based on the estimated material weight, the clamping force fluctuation value, the effective contact area, and the center of gravity offset, a fuzzy PID controller is used in step B5. The controller generates dynamic clamping force control parameters, and finally adjusts the output torque of the left and right gripper drive units of the flexible clamping component based on the dynamic clamping force control parameters in step B6, so that the clamping torque on both sides is asymmetrically distributed according to the center of gravity offset. Through the multi-source sensing and dynamic torque distribution mechanism in the above six steps, the programmable logic controller realizes adaptive clamping control for asymmetrical loads. Without relying on external vision or 3D modeling, it can actively balance the overturning risk caused by the center of gravity offset by only embedded sensing and deterministic fuzzy rules. It effectively solves the safety hazards of material slippage, rotation or even falling off in the high-lift or long-extended state caused by the symmetrical application of clamping force in the background technology, and significantly improves the clamping reliability and operational safety of unmanned forklifts for irregular or off-center loaded materials.

[0050] In some embodiments, the process of controlling the lifting and telescopic assembly to perform lifting and telescopic movements further includes the following steps: Step C1: Compare the current actual position information of the lifting and telescopic component with the preset target position information to obtain the total displacement; The programmable logic controller (PLC) retrieves the current actual position information of the lifting and telescopic component obtained in step A1 of claim 2, such as a current lifting height of 500 mm and a telescopic length of 300 mm; simultaneously, it reads the preset target position information in the current task, such as a target lifting height of 2300 mm and a target telescopic length of 1200 mm. The controller calculates the displacement in the lifting direction as 1800 mm and the displacement in the telescopic direction as 900 mm, and uses the combined Euclidean distance as the total displacement, i.e., √(1800² + 900²) ≈ 2012 mm. Here, "total displacement" refers to the straight-line distance in space from the current position to the target position, in millimeters.

[0051] Step C2: Based on the total displacement and the preset maximum operating speed, determine that the motion process of the lifting and telescopic component includes three continuous stages: acceleration, constant speed, and deceleration. The programmable logic controller (PLC) reads a preset maximum operating speed value, for example, 300 mm / s. The controller determines whether the total displacement of 2012 mm obtained in step C1 is sufficient to complete the acceleration-constant speed-deceleration process. According to kinematic equations, if the total displacement is greater than or equal to (preset maximum operating speed² / preset maximum acceleration), the process is divided into three consecutive stages. In this example, since 2012 mm is much larger than the critical value, the motion process is determined to include three consecutive stages: acceleration, constant speed, and deceleration.

[0052] Step C3: Based on the preset maximum acceleration value and the preset jerk limit value, generate the velocity change curve of the acceleration segment and the velocity change curve of the deceleration segment, so that the velocity change process meets the S-curve smoothness requirements; The programmable logic controller (PLC) calls a preset maximum acceleration value (e.g., 200 mm / s²) and a preset jerk limit value (i.e., the rate of change of acceleration, e.g., 1000 mm / s³). The controller employs a seven-segment S-curve generation algorithm: in the acceleration phase, the acceleration starts from zero and rises to the maximum acceleration with a constant jerk, then decreases back to zero with the same jerk; the deceleration phase is handled symmetrically. This generates a smooth velocity change curve, ensuring the continuity of the first derivative (acceleration) and the second derivative (jerk), satisfying the S-curve smoothness requirement. Here, "S-curve smoothness requirement" refers to the absence of sudden velocity changes, acceleration shocks, or mechanical vibrations during motion.

[0053] Step C4: Based on the velocity change curve of the acceleration phase, the constant velocity value of the uniform velocity phase, and the velocity change curve of the deceleration phase, synthesize a complete S-curve velocity planning trajectory. The programmable logic controller (PLC) stitches together the acceleration phase speed change curve generated in step C3, the constant speed phase running at a preset maximum speed of 300 mm / s, and the symmetrical deceleration phase speed change curve to form a continuous, smooth, single-peaked speed-time function, i.e., a complete S-curve speed planning trajectory. The total duration of this trajectory is approximately 8.5 seconds, including 2.5 seconds for the acceleration phase, 3.5 seconds for the constant speed phase, and 2.5 seconds for the deceleration phase.

[0054] Step C5: Discretize the time based on the S-curve velocity planning trajectory to obtain the target velocity command sequence corresponding to each sampling time; The programmable logic controller (PLC) discretizes the S-curve velocity planning trajectory obtained in step C4 at a fixed control cycle (e.g., every 10 milliseconds), extracting the corresponding target velocity value at each sampling time to form a target velocity command sequence containing 850 elements. For example, the target velocity at the first sampling point is 12 mm / s, the 250th is 300 mm / s, and the 850th is 0 mm / s.

[0055] Step C6: Based on the target speed command sequence, adjust the output of the drive unit of the lifting and telescopic component in real time so that the actual movement speed of the lifting and telescopic component tracks the S-curve speed planning trajectory. The programmable logic controller reads the current actual motion speed (feedback from the encoder) in each control cycle and compares it with the target speed command at the corresponding moment in step C5 to calculate the speed deviation. It generates a correction signal through the built-in proportional-integral controller and outputs it to the drive unit of the lifting and telescopic component (such as the control voltage of the hydraulic proportional valve or the speed command of the servo motor) to adjust its output in real time, so that the actual motion speed closely follows the S-curve speed planning trajectory, thereby achieving smooth start-stop and low vibration operation.

[0056] Understandably, based on the current actual position information of the lifting and telescopic component and the preset target position information, the total displacement is obtained in step C1. Based on the total displacement and the preset maximum operating speed, step C2 determines that the motion process of the lifting and telescopic component includes three consecutive stages: acceleration, constant speed, and deceleration. Based on the preset maximum acceleration value and the preset jerk limit value, step C3 generates the speed change curves of the acceleration and deceleration stages to meet the S-curve smoothness requirements. Based on the speed change curves of the acceleration stage, the constant speed value of the constant speed stage, and the speed change curves of the deceleration stage, a complete S-curve speed planning trajectory is synthesized in step C4. Based on the S-curve speed planning trajectory, time is discretized and sampled. In step C5, the target speed command sequence corresponding to each sampling moment is obtained. Finally, based on the target speed command sequence, in step C6, the output of the drive unit of the lifting and telescopic component is adjusted in real time to make the actual movement speed track the S-curve speed planning trajectory. Through the coordinated execution of the above six steps, the programmable logic controller realizes high-smoothness speed planning and accurate tracking of the entire lifting and telescopic movement process. Without relying on external disturbance observers, it effectively suppresses mechanical vibration, hydraulic shock or load sway caused by start-stop impact, thereby avoiding clamping loosening or structural fatigue caused by unstable movement, and significantly improving the running stability and operational reliability of the unmanned forklift under high lifting and long extension conditions.

[0057] In some embodiments, the operation of the unmanned forklift further includes the following steps: Step D1: Based on the force sensor installed on the flexible clamping component, the height sensor installed on the lifting and telescopic component, and the speed detection unit installed on the moving component, the clamping force signal, lifting height signal, and travel speed signal are collected in real time. Step D2: Based on the clamping force signal, compare it with the preset clamping safety threshold to obtain the first threshold judgment result; based on the lifting height signal, compare it with the preset height safety threshold to obtain the second threshold judgment result; based on the driving speed signal, compare it with the preset speed safety threshold to obtain the third threshold judgment result. Step D3: Calculate the clamping force change rate based on the trend of the clamping force signal within a preset time window; obtain the clamping loosening trend prediction result based on the clamping force change rate being less than a preset negative change rate threshold. Step D4: Based on the results of the first threshold judgment, the second threshold judgment, the third threshold judgment, and the prediction of the loosening trend of the clamp, comprehensively determine the current safety risk level; Step D5: Based on the safety risk level being at the primary risk level, control the moving component to reduce its speed and activate a warning prompt; Step D6: Based on the high-risk level, control the moving components to stop operating, lock the electromagnetic brake, and trigger the audible and visual alarm device to issue an emergency alarm.

[0058] Understandably, based on the force sensor installed on the flexible clamping component, the height sensor installed on the lifting and telescopic component, and the speed detection unit installed on the moving component, clamping force signals, lifting height signals, and travel speed signals are collected in real time in step D1. Based on the clamping force signal and preset clamping safety thresholds, the lifting height signal and preset height safety thresholds, and the travel speed signal and preset speed safety thresholds, the first, second, and third threshold judgment results are obtained in step D2, respectively. Based on the changing trend of the clamping force signal within a preset time window, the clamping force change rate is calculated in step D3, and a clamping loosening trend prediction result is obtained. Based on the first threshold judgment result, the second threshold judgment result, the third threshold judgment result, and the clamping loosening trend prediction result, the current safety risk level is comprehensively determined in step D4. Based on the safety risk level of... In step D5, the primary risk level controls the moving component to reduce its speed and activates a warning prompt. Based on a high-risk level, in step D6, the moving component stops operating, the electromagnetic brake is locked, and an audible and visual alarm is triggered. Through the multi-parameter fusion and trend prediction mechanism of the above six steps, the programmable logic controller (PLC) upgrades from "static threshold alarm" to "dynamic risk-level response." Without relying on artificial intelligence models, it can identify clamping loosening trends in advance using only deterministic rules. It also combines height, speed, and clamping force exceeding limits for risk escalation judgment, effectively solving the problem in the background technology where single-state interlocking cannot handle complex hazardous conditions (such as high lifting + overspeed + insufficient clamping) leading to material slippage or overturning accidents. This achieves inherently safe closed-loop control of the entire unmanned forklift operation process.

[0059] In some embodiments, the process of controlling the flexible clamping assembly to perform clamping actions further includes the following steps: Step E1: Based on the multi-point pressure signal output in real time by the pressure distribution sensor array integrated on the inner side of the gripper of the flexible clamping component, the pressure distribution data of the clamping contact area is obtained. The programmable logic controller (PLC) receives real-time output signals from a pressure distribution sensor array on the inner sides of the left and right grippers of the flexible clamping assembly. This array consists of 16 miniature pressure-sensitive units on each side, arranged in a 4x4 grid. Each unit independently outputs an analog voltage of 0 to 5 volts, corresponding to a pressure of 0 to 200 kPa. The controller converts all 32 signals into pressure values, forming a set containing position coordinates (x, y) and the corresponding pressure value p, i.e., the pressure distribution data of the clamping contact area. For example, if the pressure in multiple units in the middle of the right gripper is significantly higher than that on the left, it indicates that the material is shifting to the right.

[0060] Step E2: Calculate the spatial center of gravity based on the pressure distribution data to obtain the position of the pressure center of gravity of the material on the clamping contact surface; The programmable logic controller (PLC) calculates the spatial centroid of the pressure distribution data obtained in step E1: It multiplies the coordinates (xᵢ, yᵢ) of each pressure-sensitive unit by its pressure value pᵢ, sums the results, and then divides by the total pressure value. The formula is: The x-coordinate of the center of gravity of pressure is equal to Σ(pᵢ × xᵢ) / Σpᵢ. The vertical coordinate of the pressure center of gravity = Σ(pᵢ × yᵢ) / Σpᵢ.

[0061] The calculated position of the pressure center of gravity is (+42 mm, 0 mm), where the origin is located at the center of symmetry of the gripper, and the positive x-direction points to the right. Here, the "position of the pressure center of gravity" refers to the spatial coordinates of the point of application of the equivalent resultant force on the gripping contact surface.

[0062] Step E3: Based on the comparison between the pressure center of gravity position and the preset ideal clamping center position, the material off-center load is obtained; The programmable logic controller (PLC) calls the preset ideal clamping center position, defined as (0 mm, 0 mm). The controller compares this position with the pressure center of gravity position (+42 mm, 0 mm) obtained in step E2, and calculates the lateral offset distance as 42 mm. This value is the material off-center load. Here, "material off-center load" refers to the lateral offset distance of the actual force center of the material relative to the ideal clamping center, in millimeters.

[0063] Step E4: Based on the change sequence of pressure distribution data within a continuous sampling period, calculate the force change rate at each pressure point; based on the fact that the force change rate at any pressure point is less than a preset negative change rate threshold, obtain the material sliding trend determination result; The programmable logic controller (PLC) continuously collects pressure distribution data for five control cycles (50 milliseconds per cycle, totaling 250 milliseconds). It performs linear fitting on the pressure value sequence of each pressure-sensitive unit and calculates its rate of change of force. For example, if the pressure in a unit on the right drops from 180 kPa to 150 kPa, the rate of change is -120 kPa / s. The controller compares this value with a preset negative rate of change threshold (e.g., -100 kPa / s). Since -120 < -100, it determines that there is a loosening trend at this point. If any pressure point meets this condition, the material slippage trend determination result is "slippage trend exists".

[0064] Step E5: Based on the material off-center load exceeding the preset off-center load allowable threshold, or the material sliding trend determination result indicating the existence of a sliding trend, generate a clamping state abnormality signal; The programmable logic controller (PLC) determines whether the material off-center load of 42 mm obtained in step E3 is greater than the preset off-center load allowable threshold (e.g., 40 mm), or whether the material sliding trend determination result in step E4 is "sliding trend exists," and generates a clamping state abnormality signal. In this example, the off-center load of 42 mm > 40 mm, and there is a pressure drop point, so a clamping state abnormality signal is generated, and its value is "valid."

[0065] Step E6: Based on the clamping state abnormality signal, control the moving component to reduce the travel speed and send a clamping force fine-tuning command to the flexible clamping component to compensate for off-center load or suppress slippage; In response to the clamping state abnormality signal generated in step E5, the programmable logic controller performs dual intervention: Send a command to the drive controller of the moving component to limit its current speed from 4 km / h to 1.5 km / h; Fine-tuning commands for clamping force are sent to the servo drives of the left and right grippers of the flexible clamping assembly: the target torque of the right gripper is increased by 5% and that of the left gripper is decreased by 3%, so that the center of force is shifted to the left to compensate for the right-side load of the material and enhance the overall clamping stability.

[0066] Understandably, based on the multi-point pressure signals output in real time by the pressure distribution sensor array integrated on the inner side of the gripper of the flexible clamping component, pressure distribution data of the clamping contact area is obtained in step E1. Based on the pressure distribution data, spatial centroid calculation is performed in step E2 to obtain the pressure centroid position of the material on the clamping contact surface. Based on the pressure centroid position and the preset ideal clamping center position, the material off-center load is obtained in step E3. Based on the change sequence of the pressure distribution data within the continuous sampling period, the force change rate of each pressure point is calculated in step E4. Based on the force change rate of any pressure point being less than a preset negative change rate threshold, a material sliding trend determination result is obtained. Based on the material off-center load exceeding the preset off-center allowable threshold or the material sliding trend determination result indicating the existence of a sliding trend, a clamping state abnormality is generated in step E5. The signal, based on the abnormal clamping state signal, ultimately controls the moving component to reduce its travel speed in step E6 and sends a clamping force fine-tuning command to the flexible clamping component. Through the coordinated execution of the above six steps, the programmable logic controller achieves highly sensitive perception of the material's off-center loading state and micro-sliding trend, and triggers the linkage response of speed limit and asymmetric clamping force compensation. Without relying on external vision or material models, it can actively suppress the risk of material displacement caused by off-center loading or loose contact surface simply by using embedded sensing on the gripper surface. This effectively solves the problem in the background technology that the clamping state is "black boxed," which leads to the inability to intervene in the early stage of off-center loading or sliding, ultimately resulting in material falling accidents. It significantly improves the adaptive clamping safety and operational robustness of unmanned forklifts for irregular, asymmetric, or low-friction materials.

[0067] In some embodiments, the following steps are included before controlling the flexible clamping assembly to perform the clamping action: Step F1: Based on the photosensitive chip installed in the housing, optical reflection signals are collected from the surface of the target material to obtain optical feature data of the material surface; The programmable logic controller (PLC) activates a photosensor chip mounted on the front of the housing. This chip includes a near-infrared light-emitting diode (LED) and a photodetector array. The photosensor chip emits modulated light with a wavelength of 850 nanometers towards the target material surface and receives its reflected signal. The controller samples the reflection intensity, decay time, and spectral response curve to obtain a set of optical characteristic data of the material surface containing 32 feature values. For example, the reflection intensity is 65%, the decay time is 12 microseconds, and the spectral slope is 0.8. Here, "optical characteristic data of the material surface" refers to the set of multidimensional parameters characterizing the reflective properties of the material surface, acquired and quantified by the photosensor chip.

[0068] Step F2: Match and compare the optical feature data of the material surface with the pre-stored optical feature templates of various materials to obtain the material identification result; The programmable logic controller (PLC) calls a pre-stored library of optical feature templates for various materials. For example, this library contains templates for four common materials: stainless steel, wooden pallets, plastic boxes, and cardboard boxes. Each template consists of 32 feature values ​​of the same dimension. The controller uses the Euclidean distance algorithm to calculate the distance between the material surface optical feature data obtained in step F1 and each template. The distance from the stainless steel template is 8.2. The distance from the wooden pallet template is 3.1. The distance from the plastic box template is 6.7. The distance from the cardboard template is 2.9.

[0069] The category corresponding to the minimum distance is selected, and the material identification result is "cardboard box".

[0070] Step F3: Based on the material identification result, query the preset material-clamping force mapping table to obtain the initial clamping force command that matches the material. Based on the material identification result "cardboard box" obtained in step F2, the programmable logic controller (PLC) queries a preset material-clamping force mapping table. This table specifies that the initial clamping force command corresponding to "cardboard box" is 300 Newtons; "wooden pallet" is 500 Newtons; "stainless steel" is 600 Newtons; and "plastic box" is 400 Newtons. Therefore, the controller obtains an initial clamping force command of 300 Newtons that matches the material.

[0071] Step F4: Perform a compatibility check between the initial clamping force command and the current state information of the flexible clamping component to obtain the clamping force setting value that passes the check; The programmable logic controller (PLC) reads the current status information of the flexible clamping assembly, including the drive motor temperature (45 degrees Celsius), hydraulic system pressure (12 MPa), and gripper opening (fully open). The system has a preset safety rule: if the motor temperature exceeds 80 degrees Celsius or the hydraulic pressure falls below 10 MPa, the clamping force must be reduced. In this example, all states are normal, so the compatibility check passes, and the clamping force setting is the initial clamping force command of 300 Newtons.

[0072] Step F5: Based on the clamping force setting value, send a clamping force configuration command to the drive unit of the flexible clamping component; The programmable logic controller (PLC) converts the clamping force setting of 300 Newtons determined in step F4 into a current command (e.g., 1.8 Ampers) recognizable by the servo driver and sends a clamping force configuration command to the drive unit of the flexible clamping assembly. This command includes the target torque value, response slope, and limiting parameters to ensure smooth and controllable execution.

[0073] Step F6: Based on the clamping force configuration command, control the flexible clamping component to output a clamping force that does not exceed the clamping force setting value when performing the clamping action; During subsequent clamping actions, the drive unit of the flexible clamping component monitors the output torque in real time and ensures through closed-loop control that the actual clamping force does not exceed the clamping force setting of 300 Newtons configured in step F5. Even if the operator remotely triggers "full clamping," the system forcibly limits the output upper limit to prevent the carton from deforming or breaking due to over-clamping.

[0074] Understandably, the optical reflection signal acquisition of the target material surface based on the photosensitive chip installed in the housing is obtained in step F1 to obtain optical feature data of the material surface. Based on the optical feature data of the material surface, it is matched and compared with pre-stored optical feature templates of various materials in step F2 to obtain the material material identification result. Based on the material material identification result, a preset material-clamping force mapping table is queried in step F3 to obtain an initial clamping force command matching the material material. Based on the initial clamping force command and the current state information of the flexible clamping component, a compatibility check is performed in step F4 to obtain a clamping force setting value that passes the check. Based on the clamping force setting value, a clamping force configuration command is sent to the drive unit of the flexible clamping component in step F5. Finally, Based on the clamping force configuration command, step F6 controls the flexible clamping component to output a clamping force that does not exceed the set clamping force value when performing the clamping action. Through the coordinated execution of the above six steps, the programmable logic controller realizes non-contact, rapid, and automated identification of the material before clamping, and dynamically configures the appropriate upper limit of clamping force accordingly. Without relying on manual input or barcode scanning, it effectively solves the safety hazards in the background technology caused by applying excessive clamping force to light and fragile materials (such as cardboard boxes) due to fixed clamping force or reliance on experience setting, resulting in damage, or insufficient clamping force to heavy materials causing slippage. It significantly improves the adaptability of unmanned forklifts to multi-material mixed operation scenarios and the universal safety of clamping operations.

[0075] In some embodiments, after the clamping force value of the flexible clamping component is lower than a preset second proportion of a preset clamping force threshold and a shutdown is triggered, the following steps are further included: Step G1: Based on the judgment result that the clamping force value is lower than the preset clamping force threshold by a preset second ratio, control the moving component to stop running and trigger the audible and visual alarm device, and at the same time record the current clamping state as an abnormal shutdown state. For example, the programmable logic controller (PLC) confirms that the current clamping force is 390 Newtons, while the preset clamping force threshold is 500 Newtons, resulting in a ratio of 78%, which is lower than the preset second ratio of 80%. Based on this, the controller determines that a severe clamping failure condition is met and immediately performs three operations: Send an emergency stop command to the moving component drive unit, cut off power, and activate the electromagnetic brake; Activate the audible and visual alarm device installed on the top of the housing, which emits a flashing red light and a 1 kHz buzzer sound; Mark the current clamping state as "abnormal shutdown state" in the system status register.

[0076] Here, "abnormal shutdown state" refers to a safety shutdown event triggered by insufficient clamping force.

[0077] Step G2: Based on the abnormal shutdown state, send a fine-tuning command for clamping force to the flexible clamping component, so that the flexible clamping component performs a small incremental clamping action based on the original clamping position; For example, within 500 milliseconds after a shutdown, the programmable logic controller (PLC) sends a fine-tuning command for the clamping force to the servo driver of the flexible gripping assembly, requesting a small incremental clamping action based on the current position. This action is defined as: the left and right grippers move inward synchronously by 0.5 mm, corresponding to a target clamping force increment of +30 Newtons. This displacement is less than the elastic deformation threshold of the material to avoid damage.

[0078] Step G3: Based on the stable state after the small incremental clamping action is completed, reacquire the updated clamping force value output by the flexible clamping component; For example, after the small incremental clamping action in step G2 is completed, the programmable logic controller waits for 200 milliseconds to ensure system stability, and then reads the new value output by the force sensor built into the flexible clamping component to obtain the updated clamping force value of 435 Newtons.

[0079] Step G4: Compare the updated clamping force value with the preset first ratio of the preset clamping force threshold to obtain the clamping recovery determination result; For example, the programmable logic controller (PLC) calls a preset first ratio (e.g., 90%) to calculate 90% of the preset clamping force threshold of 500 Newtons, which is 450 Newtons. The updated clamping force value of 435 Newtons obtained in step G3 is compared with 450 Newtons: since 435 < 450, the clamping recovery determination result is "not recovered"; if ≥ 450, it is "recovered". In this example, the result is "not recovered", but for the sake of illustrating the complete process, it is assumed that after the second fine-tuning, the force increases to 460 Newtons, then it is determined to be "recovered".

[0080] Step G5: Based on the clamping recovery determination result that the updated clamping force value is not lower than the preset clamping force threshold, the alarm state of the audible and visual alarm device is deactivated, and the operating permission of the moving component is restored to the low-speed driving mode. For example, when the clamping recovery determination result is "recovered" (i.e., the updated clamping force value is not less than 450 Newtons), the programmable logic controller performs the recovery operation: Send a shutdown command to the audible and visual alarm device to stop the output of lights and sound; Switch the running permission of the mobile component from "prohibited" to "allow low-speed driving mode", with a maximum speed limit of 1 km / h.

[0081] Step G6: Based on the mobile component being in a low-speed driving mode, control the unmanned forklift to return to the preset safe area at a speed not exceeding the preset low-speed driving speed; For example, the programmable logic controller (PLC) initiates a preset safe return procedure: it calls the coordinates of the nearest preset safe area (e.g., the location of a charging station: X=10.0 meters, Y=5.0 meters), plans a straight path to avoid obstacles, and controls the moving component to return along this path at a preset low speed (1 km / h). During the return process, the clamping force is continuously monitored, and if it falls below 450 Newtons again, the shutdown is triggered again.

[0082] Understandably, based on the judgment result that the clamping force value is lower than the preset clamping force threshold by a preset second ratio, step G1 controls the moving component to stop running and triggers the audible and visual alarm device, while recording the current clamping state as an abnormal stop state. Based on the abnormal stop state, step G2 sends a clamping force fine-tuning command to the flexible clamping component to perform a small incremental clamping action. Based on the stable state after the small incremental clamping action is completed, step G3 re-acquires the updated clamping force value output by the flexible clamping component. Based on the updated clamping force value and the preset first ratio of the preset clamping force threshold, step G4 obtains the clamping recovery judgment result. Based on the clamping recovery judgment result, the updated clamping force value is not lower than the preset second ratio. In step G5, a preset first ratio of the clamping force threshold is set, the alarm state of the audible and visual alarm device is deactivated, and the operating permission of the moving component is restored to the low-speed driving mode. Finally, based on the moving component being in the low-speed driving mode, in step G6, the unmanned forklift is controlled to return to the preset safe area at a speed not exceeding the preset low-speed driving speed. Through the closed-loop recovery mechanism of the above six steps, the programmable logic controller realizes automatic diagnosis, fine-tuning compensation, and safe degraded return to the starting point for clamping failure events without relying on manual intervention. While effectively preventing secondary accidents caused by material falling, it also avoids complete interruption of operation due to a single clamping fluctuation, significantly improving the autonomous fault tolerance capability and system availability of the unmanned forklift under complex working conditions.

[0083] According to an embodiment of the second aspect of this application, such as Figure 2 , Figure 3 and Figure 4 Unmanned forklifts, including: Casing 1; Movable component 2 is connected to housing 1 and is used to move housing 1. The lifting and telescopic component 3 is connected to the housing 1; The flexible clamping component 4 is connected to the lifting and telescopic component 3. The lifting and telescopic component 3 is used to drive the flexible clamping component 4 to move up and down, i.e. to move forward and backward. The flexible clamping component 4 is used to clamp materials, and the clamping force of the flexible clamping component 4 is adjustable.

[0084] Understandably, the moving component 2 first moves the housing 1 to the front of the target material; the lifting and telescopic component 3, according to the task instruction, raises and lowers the flexible clamping component 4 to the target height and extends it to both sides of the material; the flexible clamping component 4 performs the clamping action, and its clamping force is dynamically set according to the material type; after clamping is completed, the moving component 2 moves the entire machine to transport the material to the target shelf. The entire process is coordinated and controlled by a programmable logic controller to ensure that the actions of each component are orderly and interlocked for safety.

[0085] The unmanned forklift organically integrates four functional modules: movement, lifting, extension, and flexible clamping. The adjustable clamping force of the flexible clamping component 4 allows it to adapt to materials of different materials and weights, preventing damage or slippage. The lifting and extension component 3 provides three-dimensional spatial positioning capabilities to meet the needs of multi-level racking operations. The movement component 2 features high-precision navigation and stable drive performance. The housing 1 serves as a load-bearing platform, ensuring the rigidity of the overall structure and equipment protection. The overall structure is compact, functionally complete, safe, and reliable, making it suitable for automated scenarios such as intelligent warehousing and logistics distribution.

[0086] In some embodiments, the lifting and telescopic assembly 3 includes a lifting drive 31 and a telescopic drive 32. The lifting drive 31 is connected to the housing 1, the telescopic drive 32 is connected to the lifting drive 31, and the flexible clamping assembly 4 is connected to the telescopic drive 32. The lifting drive 31 is used to drive the telescopic drive 32 to move up and down relative to the housing 1, and the telescopic drive 32 is used to drive the flexible clamping assembly 4 to move horizontally and telescopically relative to the housing 1.

[0087] Understandably, the lifting drive component 31 moves first, causing the entire telescopic drive component 32 and the flexible clamping assembly 4 to move vertically up and down relative to the housing 1, so that the clamping assembly reaches the target shelf height. Subsequently, the telescopic drive component 32 moves, pushing the flexible clamping assembly 4 to extend horizontally and insert it under the material (such as a pallet). After clamping is completed, the telescopic drive component 32 retracts first, then the lifting drive component 31 descends, and finally the moving component 2 drives the housing 1 away. Throughout the process, the lifting and telescopic movements are decoupled and executed sequentially to avoid interference, and all movements are based on the housing 1 as a fixed reference frame.

[0088] By directly connecting the lifting drive component 31 to the housing 1, the telescopic drive component 32 to the lifting drive component 31, and the flexible clamping assembly 4 to the telescopic drive component 32, a hierarchical mechanical transmission chain is formed: "Housing 1 → Lifting drive component 31 → Telescopic drive component 32 → Flexible clamping assembly 4". This design features a compact structure, reasonable force distribution, and clear motion decoupling. This design not only enables independent and controllable movement of the flexible clamping assembly 4 in both vertical and horizontal degrees of freedom, but also ensures the structural stability of the entire machine in the raised state. It effectively supports subsequent multi-dimensional safety control logic based on height, clamping force, and speed, providing a solid mechanical foundation for the reliable operation of unmanned forklifts in complex warehousing environments.

[0089] In some embodiments, the flexible clamping assembly 4 includes a clamping drive 41 and a gripper 42. The clamping drive 41 is connected to the gripper 42. The clamping drive 41 is used to drive the gripper 42 to open and close so that the gripper 42 can be used to clamp materials. The clamping force of the clamping drive 41 can be infinitely adjusted between aN and bN, where b is greater than a.

[0090] It is understood that the clamping drive unit 41 is an electrically driven actuator, and its output end is connected to the movable joint of the gripper 42 via a mechanical linkage or direct transmission. The gripper 42 has at least two relatively movable clamping arms, which respectively constitute the left gripper 42 and the right gripper 42. The two are arranged symmetrically and are mounted on the base of the flexible clamping assembly 4 via a hinge structure. When the clamping drive unit 41 is activated, its output force or displacement is converted into the rotational or translational motion of the gripper 42 through the transmission mechanism, thereby realizing the opening and closing of the gripper 42 and completing the clamping or release of materials.

[0091] The clamping drive unit 41 is equipped with a closed-loop force control unit, which includes a force sensing element and a drive adjustment module. The force sensing element detects the force generated during clamping in real time and feeds the signal back to the drive adjustment module. The drive adjustment module dynamically adjusts the drive output according to preset instructions, so that the clamping force can be continuously and smoothly adjusted between a preset lower limit aN and a preset upper limit bN, and the adjustment process has no discrete gear switching, achieving true stepless adjustment. Here, aN is the minimum effective clamping force allowed by the system, bN is the maximum safe clamping force allowed by the system, and b > a.

[0092] In other words, this embodiment ensures that the flexible clamping component 4 can set the appropriate clamping force as needed under different material types, weights and surface characteristics, which avoids material slippage due to insufficient clamping force and also prevents material deformation or damage due to excessive clamping force.

[0093] According to the embodiments of the fourth aspect of this application, such as Figure 5As shown, the electronic device may include a processor 310, a communications interface 320, a memory 330, and a communication bus 340. The processor 310, communications interface 320, and memory 330 communicate with each other via the communication bus 340. The processor 310 can call logical instructions from the memory 330 to execute unmanned forklift control methods.

[0094] Furthermore, the logical instructions in the aforementioned memory 330 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0095] On the other hand, this application also provides a computer program product, which includes a computer program stored on a non-transitory computer-readable storage medium. The computer program includes program instructions, and when the program instructions are executed by the computer, the computer is able to execute the unmanned forklift control method provided by the above methods.

[0096] According to an embodiment of the fifth aspect of this application, the application further includes a non-transitory computer-readable storage medium having a computer program stored thereon that, when executed by a processor, is implemented to perform the unmanned forklift control methods provided above.

[0097] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0098] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platforms, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solutions, in essence or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., including several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute the methods of various embodiments or some parts of embodiments.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate this application and are not intended to limit this application. Although this application has been described in detail with reference to the embodiments, those skilled in the art should understand that various combinations, modifications, or equivalent substitutions of the technical solutions of this application do not depart from the spirit and scope of the technical solutions of this application and should be covered within the scope of the claims of this application.

Claims

1. A control method for an unmanned forklift, applied to an unmanned forklift, characterized in that, The unmanned forklift includes a housing, a moving component, a lifting and telescopic component, and a flexible clamping component. The moving component is connected to the housing and is used to move the housing. The lifting and telescopic component is connected to the housing. The flexible clamping component is connected to the lifting and telescopic component and is used to drive the flexible clamping component to move up and down, i.e., to extend and retract. The flexible clamping component is used to clamp materials, and the clamping force of the flexible clamping component is adjustable. The unmanned forklift control method includes the following steps: Step S1: Obtain the current position information of the housing based on the laser navigation system, and compare the current position information with the position information of the preset target area to obtain the position deviation value; if the position deviation value is less than or equal to the preset position deviation threshold, and the speed of the moving component is continuously lower than the preset speed threshold for more than the preset stopping confirmation time, it is determined that the housing has stopped. Step S2: Based on the determination that the housing has stopped, send a lifting and lowering command to the programmable logic controller; based on the lifting and lowering command, control the lifting and telescopic components to perform lifting and telescopic movements until the flexible clamping components reach the preset working height and preset extension position; Step S3: Based on the arrival signal of the lifting and telescopic component reaching the preset working height and the preset extension position, send a clamping permission command to the programmable logic controller; based on the clamping permission command, control the flexible clamping component to perform clamping action, and obtain the clamping force value output by the flexible clamping component in real time; Step S4: Based on the comparison between the clamping force value and the preset clamping force threshold, a clamping state determination result is obtained; based on the clamping state determination result that the clamping force value is lower than the preset clamping force threshold by a preset first proportion, the moving component is controlled to reduce the driving speed from the normal driving speed to the preset low driving speed. Step S5: Based on the fact that the clamping force value is further lower than the preset second ratio of the preset clamping force threshold, control the moving component to stop running immediately and trigger the audible and visual alarm device to sound an alarm; Step S6: Based on the fact that the current lifting height of the lifting and telescopic component is greater than a preset height threshold, control the travel speed of the moving component to be limited to no more than a preset speed limit value, and prohibit the moving component from performing sharp turning operations with a steering angular velocity greater than a preset steering angular velocity threshold.

2. The unmanned forklift control method according to claim 1, characterized in that, The process of controlling the lifting and telescopic assembly to perform lifting and telescopic movements, and controlling the flexible clamping assembly to perform clamping actions, also includes the following steps: Step A1: Based on the real-time acquisition of the lifting displacement signal and the telescopic displacement signal by the magnetostrictive displacement sensor installed on the lifting and telescopic assembly, obtain the current actual position information of the lifting and telescopic assembly; Step A2: Compare the current actual position information with the preset target position information to obtain a position deviation signal; based on the position deviation signal, generate a position control output signal through an adaptive fuzzy PID controller; Step A3: Based on the output torque signal collected in real time by the torque sensor installed on the flexible clamping assembly, obtain the current actual clamping force information of the flexible clamping assembly; Step A4: Compare the current actual clamping force information with the preset clamping force command to obtain a clamping force deviation signal; generate a force feedforward compensation signal based on the clamping force deviation signal; Step A5: The position control output signal and the force feedforward compensation signal are superimposed to obtain a composite control signal; Step A6: Based on the composite control signal, synchronously adjust the output of the drive unit of the lifting and telescopic component and the output of the drive unit of the flexible clamping component so that the motion trajectory of the lifting and telescopic component is dynamically matched with the clamping force of the flexible clamping component.

3. The unmanned forklift control method according to claim 1 or 2, characterized in that, The process of controlling the flexible clamping assembly to perform the clamping action also includes the following steps: Step B1: Based on the comparison between the drive current signal of the flexible clamping component when it initially contacts the material and the preset no-load current reference value, the estimated weight of the material is obtained. Step B2: Based on the output torque signal continuously collected by the torque sensor of the flexible clamping component during the clamping process, the clamping force fluctuation value is calculated; Step B3: Based on the contact pressure data output by the pressure distribution sensor array integrated on the gripper surface of the flexible clamping component, the effective contact area between the gripper and the material is obtained; Step B4: Based on the estimated weight of the material and the effective contact area, and combined with the current extension length information of the lifting and telescopic component, obtain the offset of the material's center of gravity relative to the center of gravity of the flexible clamping component; Step B5: Based on the estimated material weight, the clamping force fluctuation value, the effective contact area, and the center of gravity offset, generate dynamic clamping force control parameters using a fuzzy PID controller; Step B6: Based on the dynamic clamping force control parameters, adjust the output torque of the left and right gripper drive units of the flexible clamping assembly so that the clamping torque on both sides is asymmetrically distributed according to the center of gravity offset, thereby achieving adaptive clamping torque distribution.

4. The unmanned forklift control method according to claim 1 or 2, characterized in that, The process of controlling the lifting and telescopic assembly to perform lifting and telescopic movements also includes the following steps: Step C1: Compare the current actual position information of the lifting and telescopic component with the preset target position information to obtain the total displacement; Step C2: Based on the total displacement and the preset maximum operating speed, determine that the motion process of the lifting and telescopic component includes three continuous stages: acceleration, constant speed, and deceleration. Step C3: Based on the preset maximum acceleration value and the preset jerk limit value, generate the velocity change curve of the acceleration segment and the velocity change curve of the deceleration segment, so that the velocity change process meets the S-curve smoothness requirements; Step C4: Based on the speed change curve of the acceleration segment, the constant speed value of the uniform speed segment, and the speed change curve of the deceleration segment, synthesize a complete S-curve speed planning trajectory; Step C5: Discretize the time based on the S-curve velocity planning trajectory to obtain the target velocity command sequence corresponding to each sampling time; Step C6: Based on the target speed command sequence, adjust the output of the drive unit of the lifting and telescopic component in real time so that the actual movement speed of the lifting and telescopic component tracks the S-curve speed planning trajectory.

5. The unmanned forklift control method according to claim 1 or 2, characterized in that, The unmanned forklift operation also includes the following steps: Step D1: Based on the force sensor installed on the flexible clamping assembly, the height sensor installed on the lifting and telescopic assembly, and the speed detection unit installed on the moving assembly, the clamping force signal, lifting height signal, and travel speed signal are collected in real time. Step D2: Based on the clamping force signal, compare it with a preset clamping safety threshold to obtain a first threshold judgment result; based on the lifting height signal, compare it with a preset height safety threshold to obtain a second threshold judgment result; based on the driving speed signal, compare it with a preset speed safety threshold to obtain a third threshold judgment result. Step D3: Based on the changing trend of the clamping force signal within a preset time window, calculate the clamping force change rate; based on the fact that the clamping force change rate is less than a preset negative change rate threshold, obtain the clamping loosening trend prediction result; Step D4: Based on the first threshold judgment result, the second threshold judgment result, the third threshold judgment result, and the clamping loosening trend prediction result, comprehensively determine the current safety risk level; Step D5: Based on the fact that the safety risk level is a primary risk level, control the mobile component to reduce its speed and activate a warning prompt; Step D6: Based on the fact that the safety risk level is high risk level, control the moving component to stop operating, lock the electromagnetic brake, and trigger the audible and visual alarm device to issue an emergency alarm.

6. An unmanned forklift, characterized in that, include: case; A movable component, connected to the housing, is used to move the housing; A lifting and telescopic assembly is connected to the housing; A flexible clamping component is connected to the lifting and telescopic component. The lifting and telescopic component is used to drive the flexible clamping component to move up and down, i.e., to move forward and backward. The flexible clamping component is used to clamp materials, and the clamping force of the flexible clamping component is adjustable.

7. The unmanned forklift according to claim 6, characterized in that, The lifting and telescopic assembly includes a lifting drive and a telescopic drive. The lifting drive is connected to the housing, and the telescopic drive is connected to the lifting drive. The flexible clamping assembly is connected to the telescopic drive. The lifting drive is used to drive the telescopic drive to move up and down relative to the housing, and the telescopic drive is used to drive the flexible clamping assembly to move horizontally and telescopically relative to the housing.

8. The unmanned forklift according to claim 6, characterized in that, The flexible clamping assembly includes a clamping drive and a gripper. The clamping drive is connected to the gripper and is used to drive the gripper to open and close so that the gripper can be used to clamp materials. The clamping force of the clamping drive can be infinitely adjusted between aN and bN, where b is greater than a.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the computer program, it implements the unmanned forklift control method according to any one of claims 1 to 5.

10. A non-transitory computer-readable storage medium, the non-transitory computer-readable storage medium comprising a computer program, characterized in that, When the computer program is executed by the processor, it implements the unmanned forklift control method according to any one of claims 1 to 5.

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