238 results about "Load sensing" patented technology

An in-situ fretting corrosion fatigue testing machine based on synchrotron radiation diffraction and three-dimensional (3D) imaging includes an axial fatigue loading system, a fretting loading system, and a corrosion environment control system, where the axial fatigue loading system includes a driving device, a load control device, and a load sensing device; the load sensing device is configured to measure an axial force and a normal force in real time; the driving device is configured to drive the load control device, thereby achieving axial displacement of the load control device; the load control device is configured to carry out axial fatigue loading of a specimen; and the fretting loading system includes a fretting wear device. The testing machine achieves real-time 3D imaging characterization of wear spot and crack morphology of a material in a fretting corrosion environment, as well as characterization of a residual stress evolution law.

The invention relates to the technical field of power conversion, and discloses an intelligent power converter system based on adaptive load regulation and a control method thereof. Comprising a power converter body, a plurality of sockets of different types are arranged on the power converter body, and a load sensing sensor, a micro-control unit, a step-down circuit and a bridge circuit are arranged in the power converter body; the load sensing sensor is electrically connected with the micro-control unit and is used for monitoring the power requirement of equipment connected with each socket in real time and transmitting a corresponding monitoring signal to the micro-control unit; the micro-control unit is electrically connected with the step-down circuit and the bridge circuit, and is used for controlling the step-down circuit and the bridge circuit to adjust output voltage and current according to a monitoring signal transmitted by the load sensing sensor; the micro-control unit controls the step-down circuit and the bridge circuit to automatically adjust the output voltage and current of the corresponding jacks according to the equipment power requirement monitored by the load sensing sensor, so as to realize the self-adaptive load adjustment of each jack.

The invention discloses an electric vehicle charging load power grid operation real-time scheduling optimization method and system, belongs to the technical field of electric vehicles, and solves the problems of insufficient coordination of new energy consumption and network congestion regulation and weak real-time dynamic response capability in electric vehicle charging load power grid operation real-time scheduling optimization. Comprising the following steps: constructing a vehicle-road-network coupling three-domain knowledge graph fusion framework, bidirectionally coupling electric vehicle charging and discharging behavior dynamic sensing and charging pile load sensing, outputting a final optimization scheme, and pushing the optimization scheme to a user side, a power grid side and a road network side; according to the method, the coupling relation among the vehicle, the network and the power grid is considered, the power grid blocking peak regulation problem is solved through coupling of the three knowledge maps and the charging and discharging characteristics of the electric vehicle, the collaboration of new energy consumption and network blocking regulation and control is enhanced, the real-time dynamic response capability of the electric vehicle is improved, and the power grid blocking peak regulation and control efficiency is improved. And technical reference is provided for power grid operation management personnel.

The invention relates to the technical field of engineering machinery, and particularly discloses an electrically-driven metering pump load-sensitive system, a control method and engineering machinery, the electrically-driven metering pump load-sensitive system comprises a control unit, a driving motor assembly, a metering pump, a pilot hydraulic control unit, a pilot handle assembly, a load-sensitive valve assembly, an actuator assembly, a sensor assembly and a pressure difference control module; the driving motor drives the metering pump to supply oil to the load-sensitive valve assembly so as to drive the actuator assembly to operate; the control unit receives the maximum outlet pressure and the maximum load pressure of the pump collected by the pressure sensor, receives a system target pressure difference signal of the pressure difference control module at the same time, and synchronously controls the rotating speed of the motor and the valve target pressure difference output by the proportional pressure reducing valve. The system aims to solve the problems that a traditional upstream compensation load sensitive system lacks a flow saturation resisting function, and a downstream compensation load sensitive system has extra reversing energy consumption and fixed system pressure difference setting.

The invention belongs to the technical field of coal mine drilling robot control, and particularly relates to a full-autonomous drilling control system and method for a coal mine drilling robot, and the system comprises the coal mine drilling robot, a drilling load sensing module, a drilling process controller, and a drilling system installed on the coal mine drilling robot. The drilling system comprises a drill rod rotation module, a drill rod feeding module and a drill rod clamping module; the drill rod rotation module comprises a hydraulic motor and a speed reducer, and the hydraulic motor is responsible for lifting power and controlling the drilling speed; the drill rod feeding module comprises a hydraulic cylinder and a guide rail. The drill rod clamping module comprises a front vice and a rear vice. The drilling load sensing module comprises a drilling pressure sensor, a rotary encoder, a drilling displacement sensor and a drilling load solver, the drilling load solver classifies and defines drilling loads based on a support vector machine, and then drilling load sensing under different coal rock conditions is achieved.

The invention discloses an intelligent charging management system of a new energy automobile, and relates to the technical field of charging control of the new energy automobile, and the system comprises a user identification and authentication module which supports three authentication modes, account association related information and authentication encryption transmission; the charging demand prediction module collects multiple types of data, and predicts charging related parameters through a fusion algorithm; the charging pile and battery state monitoring module collects various operation data in real time; the power grid load sensing module collects power grid information and synchronizes peak and valley periods; the charging strategy optimization module dynamically adjusts a charging scheme in combination with multi-source data; the safety protection module has six protection functions and a fault diagnosis capability; the data storage module adopts a distributed database and an encryption technology; the man-machine interaction module supports multiple operation modes and displays key information; and the communication coordination module is responsible for multi-terminal data interaction and protocol conversion. According to the invention, intelligence and accuracy of charging management are improved, safety protection and data safety are enhanced, and multi-scene charging requirements are met.

Systems and methods are disclosed for a lid insert and cover for use with a utility box having any type of instrument, e.g., a leak detection or geo-location instrument, with an antenna for transmitting any type of signals related to the instrument, e.g., a leak detection, geo-location or electrical current or load sensing signal. The insert may include a top plate configured to be mounted in an upper recess of the cover and a bottom plate configured to be mounted in a lower recess of the cover. The bottom plate may define a plurality of openings for fasteners, e.g., screws, bolts or other mechanical mounting mechanisms and / or zip-ties, that are configured for securing the instrument and / or its antenna within the box. When properly mounted therein, the antenna of such instruments can effectively transmit or receive signals into and out of the utility box.

The invention discloses a real-time road condition-oriented AGV collaborative congestion avoidance path planning method, and relates to the technical field of AGV path planning, and the method comprises the steps: building a global road condition map based on AGV state data, and carrying out the dynamic updating of the global road condition map, and the dynamic updating comprises the weight updating based on an AGV density value and an average speed; based on the updated global road condition map, adopting a path planning algorithm to generate an AGV global optimization cooperative path set; the cooperative path set is converted into a control instruction, dynamic compensation is carried out on the control instruction through load sensing, and a corrected control instruction is obtained and issued to the AGV; according to the method, global road condition dynamic updating is combined with dynamic control of collaborative path optimization and load perception, multi-AGV global flow balance and real-time congestion prevention are achieved, and the problems that under the high load, path conflicts are frequent, local congestion cannot be actively adjusted, and the overall efficiency is reduced due to single AGV optimization are solved.

The invention relates to the technical field of artificial intelligence and unmanned aerial vehicles, and discloses a multi-unmanned aerial vehicle cooperative navigation method based on deep reinforcement learning, the method is suitable for multi-agent task execution in a complex dynamic environment, the method is constructed by adopting a multi-agent dual deep Q network model, a centralized training and distributed execution architecture is combined, and in a training stage, the multi-agent dual deep Q network model is constructed; through a global state optimization cooperation strategy, each unmanned aerial vehicle autonomously decides according to local observation in an execution stage, and dynamically adjusts an information synchronization frequency based on a communication load sensing mechanism so as to reduce communication bandwidth occupation and improve system real-time performance, and the method also introduces an experience playback and priority sampling mechanism to improve model stability and convergence speed. The system can sense obstacle information, energy consumption level and other unmanned aerial vehicle states in real time, realizes path dynamic optimization and formation keeping, has good task adaptability and expandability, and is suitable for collaborative navigation application of a heterogeneous unmanned aerial vehicle system.

The invention provides a self-adaptive pulse width modulation method, medium and system for a charging pile, and belongs to the technical field of charging piles. The self-adaptive pulse width modulation method comprises the following steps: acquiring voltage and current values of a battery, calculating a charge state parameter and a tilt change rate of the battery, and calculating a load coefficient and a third-order precision index by combining a load sensing algorithm; and analyzing the current waveform by using Fourier transform to obtain a harmonic distortion index, and calculating a delay compensation function value. The core technology is to call a deep residual neural network model of a double-path parallel architecture, input multi-dimensional characteristic parameters, output optimal pulse width modulation parameters and generate pulse width modulation signals to adjust charging characteristics. Meanwhile, the temperature and the internal resistance value of the battery are monitored in real time, parameter updating is triggered when the preset threshold value is exceeded, a complete closed-loop control cycle is formed, and the technical problem that the pulse width modulation parameter accurately adapts to the change of the charging state of the battery under the complex dynamic load condition is effectively solved.

The invention discloses an EtherCAT master station synchronous control method and system based on a microkernel operating system, and belongs to the technical field of industrial automation field bus control. According to the system, a microkernel architecture is adopted, an EtherCAT protocol stack and a universal network protocol stack are deployed as two independent user mode processes, and data interaction is carried out through an inter-process communication and shared memory mechanism provided by a microkernel. According to the method, through a bidirectional dynamic clock compensation mechanism, static compensation in an initialization stage and dynamic compensation in an operation stage of a system are combined; a dynamic task scheduling strategy based on load awareness is adopted, and the task execution sequence is dynamically adjusted according to the CPU utilization rate and the task priority monitored in real time; a hardware redundancy design of double clock sources and double communication links is introduced, and a progressive synchronous recovery strategy is adopted during switching. According to the invention, nanosecond-level synchronization precision and microsecond-level fault switching can be realized, and the method is suitable for industrial control scenes with extremely high requirements on real-time performance and reliability.

The invention provides a cooperative output control method for a honeycomb type flight aircraft carrier, and belongs to the technical field of honeycomb type flight aircraft carriers. An autonomous aircraft formation initialization matrix is constructed to establish a hexagonal honeycomb type space geometric structure model to determine the relative position relation of all aircrafts; a dynamic load sensing system is used for collecting load gravity center change data in real time through a torque sensor to calculate a dispersed load vector, a cooperative configuration matrix is decomposed into a low-rank matrix combination to recognize a load distribution mode, and a control vector is automatically supplemented through a matrix rank loss detection algorithm to recover a full-rank characteristic. Based on the lightweight dynamic distribution model, the output distribution processing frequency is adaptively adjusted in different intervals according to the dispersed load vector deviation value, the output distribution coefficient of each aircraft is optimized, and the technical problem of low cooperative output control precision caused by unbalanced load distribution in a multi-aircraft formation system is solved.

The invention provides an electronic mechanical braking system and method, and relates to the technical field of vehicles. According to the system, a load sensing unit monitors the load capacity of vehicle tires in real time and transmits the load capacity, collected in real time, of the vehicle tires to an electronic control unit; the electronic control unit is used for dynamically adjusting a pedal feeling curve and a wheel braking force distribution proportion in real time according to the load capacity, collected in real time, of vehicle tires, the pedal feeling curve is the best corresponding relation between pedal displacement signals of the pedal simulator and the total braking force of the whole vehicle, and then the wheel braking force distribution proportion is obtained. A braking instruction is generated according to the pedal feeling curve and the wheel braking force distribution proportion, and the braking instruction is transmitted to an electronic mechanical brake; and the electronic mechanical brake is used for braking the vehicle according to the braking instruction. Therefore, by detecting the load capacity of the vehicle tires in real time and dynamically adjusting the pedal feeling curve and the wheel braking force distribution proportion in real time according to the load capacity of the vehicle tires, the braking effect of the vehicle can be greatly improved.

A brake load measuring device of a motor vehicle brake, has a brake load sensor inserted centrally as an integral piston stop into a receiving cross bore of a housing in alignment between the pistons in the receiving cross bore. The brake load sensor is inserted in such a way that the pistons are seated in alignment with each other diametrically opposite each other on both sides of the brake load sensor. In an embodiment, a decoupled structure with a distanced offset is proposed for the protection of the load sensing system.

The invention relates to the technical field of data control, and particularly discloses a multi-motor coordination control method and system based on dynamic load compensation, and the method comprises the steps: obtaining the posture data and driving state data of a whole vehicle; estimating a current road slope angle; calculating actual vertical loads of front and rear wheels; a variable weight harmonic decomposition mechanism is adopted to execute an anti-interference and torque proportion cooperative decomposition task; and executing a multi-motor coordination control task by adopting a model prediction control algorithm. In the prior art, motor torque distribution is carried out only based on static vehicle parameters or whole vehicle homogeneous hypothesis, and especially under dynamic working conditions such as vehicle acceleration climbing, low-speed heavy load or dramatic change of load migration, accurate torque coordination and load sensing control optimization between motors cannot be realized. Due to the fact that the dynamic load compensation mechanism is constructed and coordinated control of the model predictive control algorithm is combined, the response performance and coordinated control precision of the vehicle power system are remarkably improved.

A load sensing attachment for a machine tool assembly includes a machine tool interface, a load sensing device and a bit clamp interface. The machine tool interface couples the load sensing attachment to a drive train for a machine tool of the machine tool assembly. The load sensing device detects an axial load exerted on a housing of the machine tool when the load sensing attachment is coupled to the machine tool. The bit clamp interface couples the load sensing attachment to a bit clamp that selectively receives and secures a working bit. The bit clamp interface is coupled to the machine tool interface. A machine tool assembly for performing an operation on a workpiece includes the machine tool, the bit clamp and the load sensing attachment. A method for performing an operation on a workpiece using the machine tool assembly with the load sensing attachment is also disclosed.

The present invention relates to a harmonic reducer having a load measuring unit, comprising: a wave generator having a cam plate portion having a wave surface; a flex bearing into which the cam plate portion of the wave generator is fitted and coupled; a flex spline provided outside the flex bearing and having an annular boss portion; a circular spline provided outside the flex spline and having an internal gear meshing with an external gear of the flex spline; a first body coupled to the circular spline; and a second body rotatably provided on the first body by means of a support bearing, wherein the boss portion is coupled to the second body by a plurality of second coupling bolts, and the harmonic reducer further comprises a load measuring unit coupled together by fastening of the second coupling bolts, and the load measuring unit includes a ring-shaped load sensing sensor, and the second coupling bolts are fastened by passing through the load sensing sensor.

The invention discloses a boom safety control system and high-altitude operation equipment, and the system comprises a boom multi-way valve which comprises a pressure oil port, an oil return port, a load sensing signal port and a plurality of single valve blocks connected with a plurality of execution elements in a one-to-one correspondence manner, and the single valve blocks are used for controlling the execution elements to act in a first direction or a second direction; each single valve block comprises a first-direction working port, a second-direction working port, a first-direction pressure relief port and a second-direction pressure relief port; the logic valve comprises a plurality of one-way valves, and oil inlets of the one-way valves are connected with the first-direction pressure relief ports and / or the second-direction pressure relief ports corresponding to the action directions, needing to be limited, of the execution elements; an inlet of the safety control valve block module is connected with oil outlets of the multiple one-way valves, and an outlet of the safety control valve block module is connected with the oil return tank. The operation safety of the cantilever crane can be improved.

The application discloses a multi-stage priority liquid filling valve and belongs to the technical field of hydraulic control valves of engineering vehicles.The valve adopts a modularized superposition structure, is composed of a liquid filling valve part and a steering priority valve part which are superposed upward and downward, is communicated through three internal oil channels, integrates a main overflow valve, a steering priority valve, a liquid filling priority valve, a liquid filling pressure regulating valve, a throttling check valve and a shuttle valve, realizes three-stage hydraulic oil supply control of steering highest priority, brake liquid filling secondary priority and working system lowest priority, and is provided with the main overflow valve at an oil inlet to realize system overpressure protection.The problems of complex priority control, incompatible load sensing and constant flow systems of valve parts, need of external main overflow valve, low universality, high development and use costs and the like are solved when a single pump source supplies oil to three or more systems.

The invention belongs to the technical field of thermal management and performance regulation and control of a computer hardware system, and particularly discloses a temperature and performance coordinated regulation and control method of an MODT mainboard central processing unit. The entropy production rate of the system is calculated in real time in combination with a thermodynamic entropy production evaluation mechanism, and pre-cooling or advanced frequency reduction pulse type regulation and control are triggered when entropy production exceeds the threshold; meanwhile, a biological rhythm simulation mechanism is introduced, high-frequency and low-frequency alternating periodic oscillation control is carried out on the frequency of the processor in a millisecond-level window, the two mechanisms cooperatively act on the power management unit, and microsecond-level voltage regulation and heat dissipation driving linkage is achieved. According to the technical scheme, on the premise that the hardware cost is not increased, the energy efficiency performance, the transient heat dissipation capacity and the long-term operation reliability of the system under the high dynamic load are improved.

The invention discloses a commercial vehicle full-working-condition self-adaptive braking energy management method, device and equipment based on vehicle cloud collaboration and a storage medium, and relates to the technical field of new energy automobiles, and the method comprises the steps that load sensing data, vehicle position data and battery state data are acquired; on the basis of the load sensing data, the vehicle position data and a predefined vehicle dynamics model, recoverable energy under a corresponding vehicle planning path is predicted, and energy prediction information is determined; calculating corresponding electric braking force and mechanical braking force based on the battery state data and the energy prediction information, and determining an electric braking force distribution instruction and a mechanical braking force distribution instruction; and based on the electric braking force distribution instruction and the mechanical braking force distribution instruction, a vehicle is controlled to conduct cooperative management on braking energy. According to the method, the corresponding recoverable energy is predicted by fusing the vehicle cloud collaborative data, the distribution of the electric braking force and the mechanical braking force is dynamically optimized, and efficient self-adaptive braking energy management is achieved.

The present application relates to the technical field of vehicle body control, in particular to a vehicle body domain controller function migration method based on load sensing, comprising: collecting current load signals managed by the vehicle body domain controller and real-time function safety level information of the vehicle body domain controller; judging whether the current state of the vehicle body domain controller meets the trigger condition according to the current load signals and the corresponding real-time function safety level information; in response to the current state of the vehicle body domain controller meeting the trigger condition for function migration based on the current load signals, determining the computing power requirement threshold of the virtual domain controller currently required to be constructed according to the load type of the current load signals and the real-time function safety level information. The present application can dynamically adjust the function allocation of the controller according to the actual demand by real-time monitoring of the load signals and function safety level information of the vehicle body domain controller, and this flexibility enables the system to optimize resource use and improve overall performance under different load conditions.

The invention provides a load-sensitive multi-way valve, and belongs to the technical field of multi-way valves. The problem that oil inlet flow output of an existing hydraulic system cannot be adjusted in real time under the condition of high load is solved. The load-sensitive multi-way valve comprises a valve body, the valve body comprises an oil inlet unit and at least one reversing unit, and the oil inlet unit is provided with a main oil return way, a main oil way communicated with an external variable pump and a main feedback oil way. The reversing unit is provided with a reversing oil inlet oil way communicated with the main oil way, a reversing load pressure Ls oil way communicated with the main feedback oil way and a reversing oil return oil way communicated with the main oil return oil way, the oil inlet unit is further provided with an auxiliary oil way communicated with an external metering pump, and an unloading diverter valve capable of being communicated with the auxiliary oil way and the main oil return oil way is arranged in the oil inlet unit. A flow dividing unloading valve element capable of adjusting the flow during movement is arranged in the unloading flow dividing valve. The load-sensitive multi-way valve can adjust the ratio of the oil quantity of the auxiliary oil way entering the main oil way to the oil quantity of the main oil return way, and the oil quantity supply of the reversing oil inlet way can be adjusted in real time.

The utility model relates to the technical field of bale collecting equipment, in particular to a hydraulic system of a small square bale bundling and collecting machine. The main hydraulic system comprises a plunger variable pump, a high-pressure filter and an electric proportional multi-way valve; the plunger variable pump adopts a plunger variable pump with pressure cut-off and load sensitive functions, and the electric proportional multi-way valve is a load sensitive electric proportional multi-way valve; the plunger variable pump is powered by a power shaft of a tractor; an oil inlet of the electric proportional multi-way valve is connected with a pressure oil port of the plunger variable pump through the high-pressure filter, and the high-pressure filter filters rolling oil. A control oil return port of the electric proportional multi-way valve is connected with the oil tank, and a load pressure feedback signal output port is connected with a feedback oil port of the plunger variable pump; the electric proportional multi-way valve comprises a multi-union reversing valve which is connected with an actuator to form hydraulic loops with different functions. The hydraulic system has the advantages of being high in output efficiency, saving fuel oil, reducing oil consumption, reducing heating of the hydraulic system, prolonging the service life of hydraulic elements and reducing pollution.

The application discloses an EtherCAT master station synchronization control method and system based on a microkernel operating system, and belongs to the technical field of industrial automation fieldbus control. The system adopts a microkernel architecture, deploys an EtherCAT protocol stack and a general network protocol stack as two independent user state processes, and carries out data interaction through an inter-process communication and shared memory mechanism provided by the microkernel. The method combines static compensation in the system initialization stage and dynamic compensation in the running stage through a bidirectional dynamic clock compensation mechanism, adopts a dynamic task scheduling strategy based on load sensing, dynamically adjusts the task execution order according to the real-time monitored CPU usage and task priority, introduces a hardware redundancy design of double clock sources and double communication links, and adopts a gradual synchronization recovery strategy during switching. The application can realize nanosecond-level synchronization accuracy and microsecond-level fault switching, and is suitable for industrial control scenes with extremely high real-time and reliability requirements.

The utility model provides an air suspension system for a lifting shaft, which relates to the field of air suspensions, and adopts the technical scheme that the air suspension system comprises an air storage cylinder, a lifting air bag and a bearing air bag, and further comprises an electromagnetic valve, an air inlet of the electromagnetic valve is communicated with the air storage cylinder, and a first air outlet of the electromagnetic valve is communicated with the lifting air bag; the load sensing valve comprises a valve body and a transverse swing rod set, the valve body is arranged on the portion, between the third axle and the fourth axle, of the frame, the transverse swing rod set can be connected with the third axle and the fourth axle, an air inlet of the valve body is communicated with the air storage cylinder, a second air outlet of the electromagnetic valve is communicated with a control air port of the valve body, and an air outlet of the valve body is communicated with the bearing air bag. The height of the bearing air bag can be accurately adjusted according to the height of the frame, so that the axle load of the whole vehicle is reasonably distributed.

The application discloses a high-load industrial equipment adaptive lubrication control system and method based on dynamic load sensing, and belongs to the technical field of industrial equipment control, comprising a data acquisition module, which is used for acquiring the wind intensity of the region where the target wind turbine is located, and acquiring associated data based on the wind intensity, wherein the associated data comprises the wind intensity driving the rotation of the blades of the target wind turbine; a data processing module, which is used for distinguishing the associated data, wherein the distinguishing manner comprises distinguishing according to the wind intensity acquired on different blades, and calculating the wind intensity difference driving the rotation of each blade based on the wind intensity acquired on different blades; meanwhile, the maximum wind force and the minimum wind force driving the rotation of the blades are acquired based on the wind intensity difference. The application can perceive and accurately judge the wind intensity and load change of the wind turbine blades, improve the lubrication efficiency and the protection level of the equipment, and improve the wind power generation efficiency and the overall economic benefit.

The invention relates to the technical field of sewage treatment, and discloses an environment-friendly efficient sewage treatment system which comprises a biochemical pool, an air pressure distribution execution unit, a load induction driving module and an aeration control module, the aeration control module obtains a torque pulsation parameter in the output current of the load induction driving module, calculates real-time liquid column static pressure in the biochemical pool by using a response model, and corrects the operation frequency according to the real-time liquid column static pressure so as to maintain a pressure difference interval in which the outlet pressure is higher than the real-time liquid column static pressure; the aeration control module determines the microorganism oxygen consumption rate according to the dissolved oxygen concentration attenuation slope in the operation switching stage, and then the duty ratio of the follow-up aeration pulse period is adjusted, real-time self-adaptive adjustment of the aeration pressure along with liquid level fluctuation is achieved, sewage backflow and invalid oxygen supply risks are effectively avoided, and the aeration efficiency is improved. The accurate adaptation of the aeration rate and the actual biochemical oxygen demand of microorganisms is ensured, and the treatment efficiency and the operation stability of the system are synergistically improved.

A load sensing apparatus according to an aspect of the present invention includes a load sensing element including a pressure sensing portion, a housing that houses the load sensing element, and a pressing member supported by the housing, wherein the pressing member includes an elastic member that receives a load, a stiff pressing portion that is to come into contact with the pressure sensing portion, and an elastic supporting portion that supports the stiff pressing portion in the housing. When no load is applied to the pressing member, a gap is formed between the stiff pressing portion and the pressure sensing portion.

The utility model discloses a forklift capable of preventing goods from toppling over, and relates to the technical field of forklifts. The forklift comprises a front fork and a rear fork, wherein a limiting groove is formed in the front section of the front fork; the transmitter and the receiver are respectively mounted on two side walls of the limiting groove, and the transmitter is positioned on a receiving path of the receiver; the seesaw type limiting stopper is pivotally supported in the limiting groove through a shaft, and the rear end of the seesaw type limiting stopper is a load sensing part used for receiving the pressure of the cargo tray; the front end of the seesaw type limiting stopper is a path shielding part used for connecting and disconnecting the receiving path under the action of the cargo tray pressure received by the load sensing part, and the path shielding part can elastically deform. The forklift can judge whether the cargo tray inserted by the front fork is in place or not according to the on-off of the receiving path.