Crawler-mounted heavy-duty mower

Abstract

This invention discloses a tracked heavy-duty lawnmower, relating to the field of lawnmower technology. It includes a machine body, track wheel assembly, tracks, transmission wheel assembly, mowing components, and drive control components. The drive control components include a power source, a closed-loop pump, a travel motor, an electro-proportional valve, an electronic control system, and auxiliary hydraulic components. The electronic control system includes a data calculation and analysis component. This invention employs hydraulic transmission technology where an electro-proportional valve controls a closed-loop pump to drive the travel motor, achieving stepless speed regulation and on-the-spot steering. It can adapt to complex terrain. Through a travel resistance unit that integrates terrain scanning and sensor data, it quantifies multi-dimensional information such as terrain, slope, and speed into total travel resistance. The closed-loop pump discharge unit automatically adjusts the discharge volume according to load pressure and oil temperature, achieving on-demand oil supply. The travel stability integration unit combines overturning moment and ground pressure dynamic distribution to provide active anti-rollover intelligent safety protection for hilly and mountainous terrain.

Description

Technical Field

[0001] This invention relates to the field of lawnmower technology, specifically to a tracked heavy-duty lawnmower. Background Technology

[0002] With the increasing demand for large-scale operations in my country's agricultural and forestry greening, dike maintenance, and barren mountain management, tracked heavy-duty lawn mowers, with their advantages of low ground pressure, strong climbing ability, and good adaptability to complex terrain, are gradually replacing traditional light-duty lawn mowing equipment and becoming the core equipment for high-intensity, large-scale lawn mowing operations.

[0003] As a core component of tracked heavy-duty lawnmowers, the rationality of the drive system directly determines the equipment's operating efficiency, operational stability, energy consumption level, and range of applicable scenarios. It is a key indicator for measuring the technical level of lawnmowers. In recent years, with the iterative upgrades of mechanical manufacturing, power transmission, and automatic control technologies, the drive technology of tracked heavy-duty lawnmowers has been continuously optimized. It has gradually evolved from the initial mechanical transmission to efficient and precise drive methods such as electric motor drive and hydraulic drive. The core needs are focused on improving power transmission efficiency, enhancing adaptability to complex working conditions, reducing maintenance costs, and achieving refined control to meet the heavy-duty lawnmower operation needs in complex scenarios such as hilly terrain and muddy embankments, and to promote lawnmower operations towards mechanization, intelligence, and efficiency.

[0004] Existing tracked lawn mowers have the following problems;

[0005] Firstly, a tracked lawnmower whose engine drives the walking system via belt transmission;

[0006] This technical solution is a traditional drive method that is currently widely used in domestic tracked lawn mowers. Its core logic is to transmit power through the engine output shaft, which is then transmitted to the gearbox via the belt drive mechanism. The gearbox then adjusts the speed and torque to drive the tracked walking mechanism to move the equipment. The complete power transmission link is: engine → belt drive assembly → gearbox → drive wheel → tracked walking mechanism.

[0007] However, this tracked lawnmower has the following issues:

[0008] Low power transmission efficiency and high energy loss: There is an unavoidable elastic slippage phenomenon in the belt drive process, which leads to a large energy loss in the power transmission process and low transmission efficiency. Especially in heavy-duty lawn mowing operations, the belt slippage phenomenon will be more obvious when the load increases, which not only reduces the power utilization rate, but also increases engine fuel consumption and increases operating costs, failing to meet the high-efficiency operation requirements of heavy-duty lawn mowers.

[0009] Poor transmission stability, prone to damage and high maintenance costs: Belts are wear parts that are prone to wear, aging and breakage when working under high intensity and high load conditions for a long time. They are also greatly affected by temperature. When the engine heats up, the belt can loosen and slip, which will affect the walking stability and even cause shutdown failure. The tensioning device also needs to be adjusted and maintained regularly, which increases the workload and maintenance cost of the equipment. In addition, the frequent replacement of belts affects the continuity of operation. Especially in remote and complex operation scenarios, belt damage will cause operation interruption, making it less practical.

[0010] Low control precision and poor adaptability: This solution uses a gearbox to mechanically adjust speed and torque. The speed adjustment is limited by stages and cannot achieve stepless speed regulation. Furthermore, the steering operation relies on the mechanical structure, resulting in slow response and low control precision. It is difficult to adapt to the operation requirements of complex terrains such as hilly mountains and muddy embankments. In scenarios such as steep slopes and soft soil, it is impossible to accurately adjust the walking speed and power output, which can easily lead to problems such as track slippage and equipment sideslip. Moreover, it is difficult to turn on the spot, resulting in insufficient flexibility, which affects the operation efficiency and safety. It cannot meet the adaptability requirements of heavy-duty lawnmowers for complex terrains.

[0011] Limited structural layout and insufficient adaptability: The belt drive assembly has a large structural size and requires sufficient installation space, resulting in a less compact layout of the lawnmower chassis. In addition, the power transmission distance of the belt drive is limited, making it unable to flexibly adapt to the multi-component layout requirements of heavy-duty lawnmowers. Furthermore, the belt drive has high requirements for installation accuracy, and installation deviations can easily lead to accelerated belt wear, further reducing equipment reliability.

[0012] Secondly, a tracked lawnmower driven by an electric motor;

[0013] This technical solution is a drive method that has emerged in recent years with the development of motor and electronic control technologies. It is mainly used in medium and light-duty tracked lawnmowers, and some models with enhanced power can also be adapted for small heavy-duty lawnmowing operations. Its core logic is to use the motor to output power, directly or through a reduction gear, to drive the tracked walking mechanism, thereby realizing the movement of the equipment. The power transmission link is: motor → reduction gear → drive wheel → track walking. Some models use a direct drive method of the motor, which does not require an additional reduction gear.

[0014] However, this tracked lawnmower has the following issues:

[0015] Insufficient power output and limited adaptability: The power and torque of the motor are limited by its own structure and power supply. Although the torque can be increased by the reduction mechanism, for tracked heavy-duty lawnmowers, the heavy working load requires driving the heavy body, cutting mechanism and coping with the resistance of complex terrain. The motor drive is difficult to continuously output enough power, especially in complex working conditions such as mud, steep slopes, and gravel. When the load changes suddenly, problems such as motor overload and shutdown are likely to occur, which cannot meet the high-intensity and long-term operation requirements of heavy-duty lawnmowers. The power supply components have limited endurance. Lithium battery powered models have short endurance, while generator powered models need to be equipped with an additional engine, which increases the complexity of the equipment and energy consumption.

[0016] Poor heat dissipation and insufficient stability: During heavy-duty lawn mowing operations, the motor operates under high load for extended periods, generating a significant amount of heat. If the heat dissipation structure is not properly designed, the motor is prone to overheating, leading to decreased motor performance, shortened lifespan, or even burnout. Furthermore, the electronic controller is also prone to overheating under high load conditions, affecting control accuracy and causing the walking motion to become sluggish or uncontrollable, thus reducing the stability of equipment operation. This problem is particularly pronounced in high-temperature operating environments.

[0017] Weak anti-interference ability and poor adaptability: The motor drive system relies on the motor controller and line to transmit signals. In complex outdoor working environments, the lines are prone to aging and poor contact, and the motor controller is susceptible to interference, resulting in abnormal signal transmission and problems such as motor start-stop failure and inaccurate speed regulation. In addition, the motor and electronic control components have poor environmental adaptability. In humid, dusty, and low-temperature scenarios, the failure rate increases significantly, which cannot meet the working requirements of tracked heavy lawn mowers in complex outdoor environments. Moreover, the maintenance is difficult and requires professional personnel to inspect the electronic control system.

[0018] High cost and low cost-effectiveness: The manufacturing cost of high-power drive motors, high-precision motor controllers and supporting power supply components is high, which leads to a significant increase in the overall cost of tracked heavy-duty lawnmowers using this solution. The maintenance cost of motors and electronic control components is also high. Compared with belt drive solutions, the cost-effectiveness is low, making it difficult to promote and apply on a large scale. At the same time, the motor drive system is difficult to maintain in the later stage, requiring professional technicians to debug and repair, which further increases the user's operating costs.

[0019] In summary, neither the existing engine belt drive nor electric motor drive technologies can adequately meet the core requirements of tracked heavy-duty lawnmowers in terms of power output, operational stability, control precision, adaptability to complex working conditions, and maintenance costs. These technologies have shortcomings. Therefore, developing a highly efficient, stable, precise, and adaptable drive technology for tracked heavy-duty lawnmowers has become an urgent technical problem to be solved in this field. Summary of the Invention

[0020] The purpose of this invention is to provide a tracked heavy-duty lawn mower that solves the problems mentioned in the background art.

[0021] To achieve the above objectives, the present invention provides a tracked heavy-duty lawn mower, comprising:

[0022] The machine body has two sets of track wheel sets on its side, each set including tracks and drive wheels.

[0023] A mowing assembly, wherein the mowing assembly is disposed at the bottom of the machine body;

[0024] A drive control component, which is mounted on the machine body, is used to control the movement and operation of the lawnmower;

[0025] The drive control assembly is equipped with a hydraulic drive walking system;

[0026] The hydraulically driven walking system includes:

[0027] Power source, closed-loop pump, travel motor, electro-proportional valve, electronic control system, and auxiliary hydraulic components;

[0028] The power source is a gasoline engine, which is used to drive the closed pump to provide power to the hydraulic system;

[0029] The closed-loop pump is a variable displacement piston closed-loop pump, which enables power output on demand;

[0030] The walking motor is a cycloidal hydraulic motor with bidirectional rotation function, enabling the equipment to move forward and backward.

[0031] The electrical control system includes a PLC controller, an operation component, a pressure sensor, a speed sensor, a circuit component, and a data calculation and analysis component.

[0032] The data calculation and analysis component has a built-in adjustment and control system. By collecting data on the operation of the lawnmower and processing the data through the data calculation and analysis component, it outputs the total walking resistance, the target displacement of the closed pump, and the lateral stability coefficient.

[0033] The data calculation and analysis component is used to analyze the walking stability of the lawnmower in real time and dynamically adjust the discharge rate of the closed pump.

[0034] The auxiliary hydraulic components include a hydraulic tank, a hydraulic filter, a relief valve, a cooler, an accumulator, and hydraulic hoses.

[0035] Optionally, the output shaft of the gasoline engine is fixedly connected to the power input end of the closed pump via a coupling. When the gasoline engine is running, it drives the closed pump to run synchronously, providing power to the hydraulic drive walking system.

[0036] The oil outlet of the closed pump is connected to the inlet and outlet of the travel motor through a high-pressure hydraulic oil pipe to form a closed hydraulic transmission circuit.

[0037] The overflow valve is integrated into the closed pump, the cooler is connected in series in the return oil circuit, the accumulator is connected in parallel at the outlet of the closed pump, and the hydraulic filter element is installed at the suction port of the closed pump and the return port of the main oil circuit to ensure the cleanliness of the hydraulic oil entering the system.

[0038] The PLC controller is electrically connected to the operating component, the electro-proportional control valve, the pressure sensor, and the speed sensor. The pressure sensor is installed at the oil outlet of the closed pump to collect the hydraulic system pressure signal. The speed sensor is installed on the output shaft of the travel motor to collect the travel speed signal. After receiving the above signals, the PLC controller controls the electro-proportional control valve to adjust the displacement of the closed pump according to the instructions of the operating component, thereby achieving precise control of the travel motor. The wireless remote control module is connected to the PLC controller to realize remote operation.

[0039] Optionally, the data calculation and analysis component includes:

[0040] Multi-source sensor data acquisition module:

[0041] By collecting and analyzing data from the lawnmower during operation, we can obtain data on walking resistance, closed-loop pump discharge, and walking stability.

[0042] Transit processing module:

[0043] It receives walking resistance data, closed-loop pump discharge data, and walking stability data, cleans the acquired data, and stores it in the database;

[0044] Comprehensive Calculation Module:

[0045] The system retrieves the walking resistance data, closed-loop pump discharge data, and walking stability data processed by the transfer processing module from the database.

[0046] Comprehensive Calculation Module:

[0047] The total walking resistance is output based on the ground rolling resistance coefficient, total machine mass, gravitational acceleration, ground slope angle, and additional resistance from mowing operations in the walking resistance data.

[0048] Based on the drive wheel pitch circle radius, travel motor mechanical efficiency, travel motor volumetric efficiency, hydraulic system working pressure difference, transmission ratio between drive wheel and motor, and hydraulic oil temperature-viscosity coefficient in the closed-loop pump discharge data, and combined with the total travel resistance, the target displacement of the closed-loop pump is output.

[0049] Based on the overall machine center of gravity height, turning radius, track center distance and track ground pressure dynamic distribution coefficient in the walking stability data, and combined with the total walking resistance, the lateral stability coefficient is finally output. The lateral stability coefficient is combined with the closed pump target displacement to calculate the corrected target displacement.

[0050] Execution Management Module:

[0051] It receives the total travel resistance, the target displacement of the closed pump, and the corrected target displacement, and executes the management module to manage the electro-proportional valve and execute the hydraulic power.

[0052] Optionally, the integrated calculation module includes a walking resistance unit, a closed-loop pump discharge unit, and a walking stability integrated unit, and the execution management module includes an electro-proportional valve drive unit and a hydraulic power execution unit.

[0053] Optionally, the processing flow of the walking resistance unit is as follows:

[0054] A1. Assign values ​​based on the type of ground in the agricultural use scenario of the lawnmower to analyze the ground rolling resistance coefficient;

[0055] A2. Combine the analysis of the machine mass, gravitational acceleration, and ground slope angle, and introduce the ground slope angle in the form of sine and cosine functions to decompose the gravity in two directions: perpendicular to the ground and parallel to the ground, thereby analyzing the components perpendicular to the ground and parallel to the ground.

[0056] A3. By analyzing the additional walking resistance generated by the interaction between the cutting blades and vegetation during lawn mowing, we can analyze the changes in walking speed caused by load changes, introduce additional resistance during lawn mowing, and finally output the total walking resistance.

[0057] Optionally, the processing flow of the closed-loop pump discharge unit is as follows:

[0058] B1. By introducing the pitch circle radius of the drive wheel and combining it with the total travel resistance, we can analyze the required driving torque on the drive wheel.

[0059] B2. By analyzing the ratio of output power to input hydraulic power after mechanical friction loss in the travel motor, the degree of energy loss due to internal friction of the motor can be reflected, so as to introduce the mechanical efficiency of the travel motor.

[0060] B3. By analyzing the ratio of the actual output flow rate to the theoretical input flow rate of the travel motor, the degree of internal leakage loss of the motor can be reflected, so as to introduce the volumetric efficiency of the travel motor.

[0061] B4. By analyzing the pressure difference between the oil outlet and return port of the closed pump, the relationship between the working pressure difference and the actual load of the hydraulic system is quantified, so as to introduce the working pressure difference of the hydraulic system.

[0062] B5. By analyzing the transmission ratio of the reduction mechanism between the output shaft of the travel motor and the drive wheel, the amplification factor of the output torque of the travel motor when it is transmitted to the drive wheel is quantified, so as to introduce the transmission ratio between the drive wheel and the motor.

[0063] B6. By analyzing the dynamic synergistic relationship between the current temperature and viscosity of hydraulic oil, the temperature-viscosity synergistic weighting coefficient, real-time oil temperature, optimal operating temperature of hydraulic oil, and kinematic viscosity at the current temperature are combined and calculated to output the hydraulic oil temperature-viscosity synergistic coefficient.

[0064] Optionally, the processing flow of the walking stabilization integrated unit is as follows:

[0065] C1. By analyzing the vertical height of the lawnmower's center of gravity relative to the ground, the relationship between the center of gravity height and the risk of tipping over is quantified, thus introducing the overall center of gravity height.

[0066] C2. Analyze the turning radius of the lawnmower when it turns. It is obtained by combining the rotation speeds of the left and right motors. The turning radius is the key to the source of centrifugal force in the stability determination.

[0067] C3. By analyzing the horizontal distance between the longitudinal centerlines of the left and right tracks, the relationship between track center distance and stability is analyzed, thus introducing track center distance.

[0068] C4. By analyzing the synergistic relationship between the non-uniformity of the track ground pressure distribution and the proportion of the actual bearing area, and combining the maximum specific pressure of the track ground pressure, the average specific pressure of the track ground pressure, the actual bearing area, and the total area of ​​the track ground pressure, a dynamic distribution coefficient of track ground pressure is introduced to finally output the lateral stability coefficient. The lateral stability coefficient is then combined with the compensation strength coefficient and the target displacement of the closed pump to output the corrected target displacement.

[0069] Optionally, the processing flow of the electro-proportional valve drive unit is as follows:

[0070] The PLC controller converts the corrected target displacement into a target control current based on the calibration curve of the electro-proportional control valve of the closed pump. The PWM output module of the PLC controller generates a PWM signal with a corresponding duty cycle based on the target control current. After being amplified by the proportional amplifier, the signal drives the electromagnet of the electro-proportional valve. The valve core of the electro-proportional valve is displaced according to the magnitude of the electromagnetic force, which adjusts the swashplate angle of the closed pump so that the actual displacement of the closed pump approaches the corrected target displacement.

[0071] The processing flow of the hydraulic power actuator is as follows:

[0072] Power conversion: The engine drives the closed pump to operate through the coupling. Under the adjustment of the electro-proportional valve, the closed pump outputs hydraulic oil flow corresponding to the corrected target displacement. The high-pressure hydraulic oil is delivered to the travel motor through the high-pressure oil pipe.

[0073] Power execution: High-pressure hydraulic oil enters the travel motor, driving the motor rotor to rotate, converting hydraulic power into mechanical power. The output shaft of the travel motor drives the drive wheel to rotate, and the drive wheel meshes with the track, causing the track to generate friction with the ground, thus realizing the lawnmower's forward, backward, and turning movements.

[0074] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0075] I. This invention employs a hydraulic drive technology that uses an electro-proportional valve to control a closed-loop pump to drive the travel motor. Compared to existing engine belt drive and electric motor drive technologies, this technology offers significant advancements and practicality. The closed-loop pump and travel motor form a closed-loop hydraulic transmission circuit, ensuring efficient and stable power transmission with low energy consumption. It effectively avoids power shocks during sudden load changes, ensuring continuous and stable operation of the equipment under high loads and complex terrain. This eliminates slippage, overload, and other malfunctions, improving operational continuity. The electro-proportional valve precisely controls the closed-loop pump's displacement, achieving stepless speed regulation with a wide range, flexibly adapting to different operating scenarios. By separately controlling the speed and direction of the travel motors on both sides, smooth turning and turning on the spot are achieved, significantly improving steering flexibility. This allows for easy adaptation to complex terrains such as hills, steep slopes, and muddy areas, effectively preventing track slippage and equipment side slippage. The hydraulic transmission system is robust and wear-resistant, with no vulnerable parts, resulting in a long service life and simple maintenance, significantly reducing operating costs. The closed-loop pump can adjust the displacement in real time according to load requirements and automatically control the maximum output flow, providing high power output torque to easily handle the high-load operation needs of heavy-duty lawnmowers. It can maintain stable power output even in complex conditions such as mud, gravel, and steep slopes. The hydraulic transmission system is small and lightweight, allowing for flexible adaptation to chassis layouts. The closed-loop hydraulic circuit eliminates the need for an additional cooling circuit, further simplifying the structure, reducing overall weight, and improving mobility. The hydraulic transmission system is less affected by external electromagnetic, dust, and humidity environmental factors, exhibiting strong anti-interference capabilities. It can operate stably in complex outdoor environments such as high and low temperatures, dust, and humidity, with a low failure rate, making it suitable for various heavy-duty outdoor lawnmower operation scenarios.

[0076] Second, this invention, through a walking resistance unit, associates the ground rolling resistance coefficient with the ground type identified by ultrasonic terrain scanning and soil moisture sensing. This allows the system to automatically match the resistance benchmark according to the rolling characteristics of different agricultural terrains such as grassland, mud, and gravel. It combines the overall machine mass with the gravitational acceleration and the slope angle of the forward direction collected by the tilt sensor to accurately separate the component of gravity along the slope when traveling on a slope. It also associates the cutter head load collected by the torque sensor of the cutting mechanism with the walking speed. Through energy conversion, it calculates the additional resistance of mowing operations, enabling the system to automatically identify two states: no-load transfer and working load. The above parameters work together to quantify multi-dimensional heterogeneous information such as terrain, slope, speed, and working load into a unified total walking resistance, solving the technical problem in the prior art that the walking system cannot sense changes in external load and can only passively respond to operation commands.

[0077] Third, this invention combines the total travel resistance with the drive wheel pitch circle radius through a closed-loop pump discharge unit, converting the external load into a driving torque demand. It incorporates the mechanical efficiency and volumetric efficiency of the travel motor into the calculation, ensuring that internal friction and leakage losses are fully considered. The system working pressure difference collected in real-time by the pressure sensor is used as the denominator, allowing the displacement to automatically adjust according to the load pressure. The transmission ratio is used as the quantitative basis for torque amplification, making it applicable to models with different reduction ratios. The temperature-viscosity synergy coefficient couples the real-time oil temperature collected by the temperature sensor with the current viscosity obtained from the viscosity-temperature characteristic curve. When the oil temperature rises and the viscosity decreases, the displacement automatically increases to compensate for internal leakage losses; when the oil temperature is low and the viscosity is high, the displacement automatically decreases to utilize the high volumetric efficiency advantage. The synergistic effect of these parameters achieves an intelligent conversion from load sensing to on-demand oil supply, solving the technical problem in existing technologies where hydraulic system displacement control and oil temperature status are disconnected and cannot be dynamically compensated according to changes in oil characteristics.

[0078] IV. This invention, through a walking stability integrated unit, combines the total walking resistance with the overall machine's center of gravity height and lateral slope angle to quantify the overturning moment on a lateral slope. It also combines the overall machine mass, walking speed, and the turning radius calculated based on the speed difference between the two motors to quantify the overturning moment generated by the centrifugal force during turning. The sum of these overturning moments is compared with the stabilizing moment calculated based on the track center distance to obtain the basic stability coefficient. The innovative parameter, the dynamic distribution coefficient of ground specific pressure, synergistically couples the deviation between the maximum and average specific pressure collected by the thin-film pressure sensor array and the ratio of the actual bearing area to the total area, ensuring the ground is stable. When unevenness in the ground leads to uneven pressure distribution and the tracks are suspended in the air, the coefficient is automatically increased to make the stability judgment more stringent. When the ground is flat and fully grounded, it approaches the reference value without generating additional corrections. The corrected stability coefficient and the compensation strength coefficient are applied together to the target displacement. When the stability is sufficient, the original displacement is maintained to ensure efficiency. When the stability is insufficient, the system automatically decelerates to ensure safety. Through the synergistic effect of parameters, the system dynamically corrects the stability judgment according to the actual contact state between the tracks and the ground. This solves the technical problem in the existing technology that the stability judgment depends on the assumption of ideal uniform grounding. It provides an intelligent safety guarantee for active anti-rollover in complex agricultural terrains such as hilly and mountainous areas. Attached Figure Description

[0079] Figure 1 Axonometric view of the structure of this invention Figure 1 ;

[0080] Figure 2 Axonometric view of the structure of this invention Figure 2 ;

[0081] Figure 3 This is a schematic diagram of the data calculation and analysis component of the present invention;

[0082] Figure 4 This is a schematic diagram of the integrated computing module and execution management module of the present invention;

[0083] Figure 5 This is a schematic diagram of the operation flow of the integrated computing module of the present invention.

[0084] In the diagram: 1. Body; 2. Track wheel assembly; 3. Track; 4. Drive wheel assembly; 5. Mowing assembly; 6. Drive control assembly. Detailed Implementation

[0085] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0086] Example 1:

[0087] Please see Figures 1 to 5 This embodiment provides a tracked heavy-duty lawn mower, comprising:

[0088] The machine body 1 has two sets of track wheel sets 2 on its side. The track wheel sets 2 include tracks 3 and drive wheel sets 4.

[0089] The mowing component 5 is located at the bottom of the machine body 1;

[0090] Drive control component 6 is mounted on the machine body 1 and is used to control the movement and operation of the lawnmower.

[0091] The drive control component 6 is equipped with a hydraulic drive walking system. The core of this hydraulic drive walking technology is to convert the mechanical power of the engine into hydraulic power through a closed pump, and then convert the hydraulic power into mechanical power through the walking motor to drive the track walking. Precise control is achieved through the electronic control system.

[0092] The hydraulic drive walking technology of this invention is applicable to various types of tracked heavy-duty lawn mowers and can be adapted to complex operating scenarios such as hilly areas, embankments, barren mountains, gravelly areas and muddy areas. It is suitable for high-load, long-term and high-precision lawn mowing operations and can be widely used in agricultural and forestry greening, embankment maintenance, barren mountain management and other fields.

[0093] The hydraulically driven walking system includes:

[0094] Power source, closed-loop pump, travel motor, electro-proportional valve, electronic control system, and auxiliary hydraulic components;

[0095] The power source is a gasoline engine with a rated power of 10-30kW, which is used to drive the closed pump and provide power to the hydraulic system, adapting to the high-load operation requirements of tracked heavy-duty lawn mowers.

[0096] The closed-loop pump is the core of the power output of the hydraulic system. The closed-loop pump adopts a variable displacement piston closed-loop pump with a displacement range of 0-15ml / r, a rated working pressure of 16-25MPa, and a rated speed of 3000-4000r / min. It is equipped with an electro-hydraulic proportional control valve, which can accurately adjust the displacement through the electronic control system to achieve on-demand power output with rapid response and no obvious lag.

[0097] As a power actuator, the travel motor is selected as a cycloidal hydraulic motor or a piston hydraulic motor. The rated working pressure is matched with the closed pump (20-40MPa), and the output torque is 180-550N·m. It has a bidirectional rotation function to realize the forward and backward movement of the equipment. Its output shaft is connected to the track drive sprocket to convert hydraulic power into mechanical power to drive the track to move.

[0098] The electrical control system, as the core of the control, includes a PLC controller, operating components (operating handle, wireless remote control with display screen), pressure sensor, speed sensor, circuit components, and data calculation and analysis components. The PLC controller receives instructions from the operating components and feedback signals from the sensors. By controlling the electro-proportional control valve, it adjusts the discharge of the closed pump, thereby controlling the speed and direction of the walking motor, realizing stepless speed regulation and smooth steering. It also has functions such as fault diagnosis and overload alarm.

[0099] The data calculation and analysis component has a built-in adjustment and control system. By collecting data on the lawnmower's operation, the data is processed by the data calculation and analysis component to output the total walking resistance, the target displacement of the closed pump, and the lateral stability coefficient.

[0100] The data computing and analysis component is used to analyze the lawnmower's walking stability in real time and dynamically adjust the closed-loop pump displacement.

[0101] Auxiliary hydraulic components include a hydraulic oil tank, hydraulic filter, relief valve, cooler, accumulator, and hydraulic hoses. The hydraulic oil tank stores hydraulic oil with a capacity of 20-40L. The hydraulic filter filters impurities from the hydraulic oil to prevent damage to the hydraulic components. The relief valve prevents excessive system pressure, providing overload protection; its rated pressure is 16-25MPa. The cooler (air-cooled) cools the hydraulic oil, ensuring the oil temperature is maintained at 60-80℃ to prevent overheating from affecting system performance. The accumulator buffers pressure fluctuations in the hydraulic system, improving the smoothness of power transmission. The hydraulic hoses use high-pressure wear-resistant rubber hoses, with a pressure resistance of 30-50MPa, ensuring sealed transmission of the hydraulic oil.

[0102] Furthermore, the connection relationship of the above components is as follows:

[0103] The output shaft of the gasoline engine is fixedly connected to the power input end of the closed pump via a coupling. When the gasoline engine is running, it drives the closed pump to run synchronously, providing power to the hydraulic drive walking system.

[0104] The outlet of the closed-loop pump is connected to the inlet and outlet of the travel motor through a high-pressure hydraulic oil pipe to form a closed-loop hydraulic transmission circuit.

[0105] The overflow valve is integrated into the closed pump, the cooler is connected in series in the return oil circuit, the accumulator is connected in parallel at the outlet of the closed pump, and the hydraulic filter element is installed at the suction port of the closed pump and the return port of the main oil circuit to ensure the cleanliness of the hydraulic oil entering the system.

[0106] The PLC controller is electrically connected to the operating component, the electro-proportional control valve, the pressure sensor, and the speed sensor. The pressure sensor is installed at the oil outlet of the closed pump to collect the hydraulic system pressure signal. The speed sensor is installed on the output shaft of the travel motor to collect the travel speed signal. After receiving the above signals, the PLC controller controls the electro-proportional control valve to adjust the displacement of the closed pump according to the instructions of the operating component, thereby achieving precise control of the travel motor. The wireless remote control module is connected to the PLC controller to realize remote operation.

[0107] Furthermore, the data computing and analysis components include:

[0108] Multi-source sensor data acquisition module:

[0109] By collecting and analyzing data from the lawnmower during operation, we can obtain data on walking resistance, closed-loop pump discharge, and walking stability.

[0110] Transit processing module:

[0111] It receives walking resistance data, closed-loop pump discharge data, and walking stability data, cleans the acquired data, and stores it in the database;

[0112] Comprehensive Calculation Module:

[0113] The system retrieves walking resistance data, closed-loop pump discharge data, and walking stability data from the database after processing by the transfer processing module. The comprehensive calculation module includes a walking resistance unit, a closed-loop pump discharge unit, and a comprehensive walking stability unit.

[0114] Comprehensive Calculation Module:

[0115] The total walking resistance is output based on the ground rolling resistance coefficient, total machine mass, gravitational acceleration, ground slope angle, and additional resistance from mowing operations in the walking resistance data.

[0116] Based on the drive wheel pitch circle radius, travel motor mechanical efficiency, travel motor volumetric efficiency, hydraulic system working pressure difference, transmission ratio between drive wheel and motor, and hydraulic oil temperature-viscosity coefficient in the closed-loop pump discharge data, and combined with the total travel resistance, the target displacement of the closed-loop pump is output.

[0117] Based on the overall machine center of gravity height, turning radius, track center distance and track ground pressure dynamic distribution coefficient in the walking stability data, and combined with the total walking resistance, the lateral stability coefficient is finally output. The lateral stability coefficient is combined with the closed pump target displacement to calculate the corrected target displacement.

[0118] Execution Management Module:

[0119] The system receives the total travel resistance, the target displacement of the closed-loop pump, and the corrected target displacement. The execution management module manages the electro-proportional valve and executes the hydraulic power. The execution management module includes an electro-proportional valve drive unit and a hydraulic power execution unit.

[0120] The processing flow of the electro-proportional valve drive unit is as follows:

[0121] The PLC controller converts the corrected target displacement into a target control current based on the calibration curve of the electro-proportional control valve of the closed pump. The PWM output module of the PLC controller generates a PWM signal with a corresponding duty cycle based on the target control current. After being amplified by the proportional amplifier, the signal drives the electromagnet of the electro-proportional valve. The valve core of the electro-proportional valve is displaced according to the magnitude of the electromagnetic force, which adjusts the swashplate angle of the closed pump so that the actual displacement of the closed pump approaches the corrected target displacement.

[0122] The processing flow of the hydraulic power actuator is as follows:

[0123] Power conversion: The engine drives the closed pump to operate through the coupling. Under the adjustment of the electro-proportional valve, the closed pump outputs hydraulic oil flow corresponding to the corrected target displacement. The high-pressure hydraulic oil is delivered to the travel motor through the high-pressure oil pipe.

[0124] Power execution: High-pressure hydraulic oil enters the travel motor, driving the motor rotor to rotate, converting hydraulic power into mechanical power. The output shaft of the travel motor drives the drive wheel to rotate, and the drive wheel meshes with the track, causing the track to generate friction with the ground, thus realizing the lawnmower's forward, backward, and turning movements.

[0125] Differential steering: When steering is required, the PLC controller reduces the corrected target displacement value of the inner motor (reduces the inner track speed) based on the calculated steering radius, and increases or maintains the corrected target displacement value of the outer motor to achieve differential steering. When turning on the spot is required, the PLC controller controls the corrected target displacement of one motor to be positive (forward direction) and the other to be negative (backward direction), thereby controlling the speed and direction of the two walking motors separately and achieving smooth steering and turning on the spot.

[0126] Precise control: Operators issue speed adjustment and steering commands through operating components (operating handle or wireless remote control). After receiving the commands, the PLC controller combines the signals fed back by the pressure sensor and speed sensor to control the action of the electro-proportional control valve, which adjusts the displacement of the closed pump. When the displacement increases, the hydraulic oil output increases, the travel motor speed increases, and the equipment travel speed increases. When the displacement decreases, the hydraulic oil output decreases, the travel motor speed decreases, and the equipment travel speed decreases, thus achieving stepless speed regulation.

[0127] Protection and Stability: When the hydraulic system pressure exceeds the rated pressure of the relief valve, the relief valve automatically opens, returning excess hydraulic oil to the oil tank to prevent damage to components such as the closed-loop pump and travel motor due to excessive pressure. The cooler continues to work to dissipate heat from the hydraulic oil, ensuring that the oil temperature is maintained within the normal operating range. The accumulator buffers pressure fluctuations during sudden load changes, preventing system shocks and improving the smoothness of power transmission. The hydraulic filter element filters impurities in the hydraulic oil, extending the service life of hydraulic components.

[0128] In this embodiment:

[0129] The core of this tracked heavy-duty lawn mower is to drive the walking motor by controlling a closed pump through an electro-proportional valve. In conjunction with the electronic control system and auxiliary hydraulic components, the tracked heavy-duty lawn mower can achieve stable and efficient walking. The hydraulic drive walking system of this invention mainly consists of five parts: power source, closed pump, walking motor, electro-proportional valve, electronic control system and auxiliary hydraulic components. Each part works together to form a complete hydraulic drive walking circuit.

[0130] The walking resistance unit, closed-loop pump discharge unit, and walking stability integrated unit work together to achieve the following:

[0131] Load adaptability;

[0132] By combining the walking resistance unit and the closed-loop pump discharge unit, the system can automatically match the power output according to the real-time load without the need for manual adjustment by the operator. When the lawnmower moves from a flat road to an uphill section, the total walking resistance FR increases, and the target displacement VG of the closed-loop pump automatically increases. The closed-loop pump outputs a larger displacement to overcome the slope resistance. When moving to a downhill section, the total walking resistance FR decreases, and the target displacement VG of the closed-loop pump automatically decreases to avoid excessive speed. This capability allows the operator to focus only on the working path and the quality of mowing without frequently adjusting the walking speed.

[0133] Temperature self-compensation capability;

[0134] By introducing the hydraulic oil temperature-viscosity coefficient (VGS) in the closed-loop pump discharge unit, the system can automatically compensate for the volumetric efficiency decay caused by changes in hydraulic oil temperature. During the cold start phase, the oil temperature is low, the viscosity is high, and the volumetric efficiency is high, so VGS < 1. The target displacement VG of the closed-loop pump is appropriately reduced to avoid the travel speed exceeding expectations due to excessive displacement. After long-term operation, the oil temperature rises, the viscosity decreases, and the volumetric efficiency decreases, so VGS > 1. The target displacement VG of the closed-loop pump is appropriately increased to compensate for the power loss caused by increased leakage. This capability enables the system to maintain stable travel performance throughout the entire operating temperature range.

[0135] Safety self-protection capability:

[0136] By introducing the walking stability integrated unit, the system can proactively intervene when the risk of rollover increases, forcibly reducing displacement to slow down. The core value of this capability lies in the fact that it shifts safety decision-making from the operator's experience and reaction speed to the system's quantitative calculation and automatic execution. When working on slopes, even if the operator ignores the slope change due to focusing on mowing, the system can automatically identify the risk and take action. The introduction of the track ground pressure dynamic distribution coefficient KSN further enables the system to distinguish working conditions that appear safe but are actually dangerous. On uneven ground, even if the slope is not steep, the track part being suspended will cause the actual stability to be lower than the theoretical calculation value. The system can identify this risk earlier by correcting it with the track ground pressure dynamic distribution coefficient KSN.

[0137] The coordinated operation of the three units in this device system enables the walking system to upgrade from passive response to active decision-making;

[0138] From a broader perspective, this unit algorithm system transforms the lawnmower's walking system from a mechanical actuator into an intelligent decision-making unit. Operators no longer need to directly control the walking speed, but instead express their speed intentions through the control handle. The system judges whether it is safe to walk at this speed based on the actual working conditions and automatically adjusts it when necessary. This human-machine collaborative control mode retains the operator's control while compensating for potential blind spots and errors in human operation through the system's intelligent judgment.

[0139] Please refer to Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 The processing flow of the walking resistance unit is as follows:

[0140] A1. Assign values ​​based on the type of ground in the agricultural use scenario of the lawnmower to analyze the ground rolling resistance coefficient;

[0141] A2. Combine the analysis of the machine mass, gravitational acceleration, and ground slope angle, and introduce the ground slope angle in the form of sine and cosine functions to decompose the gravity in two directions: perpendicular to the ground and parallel to the ground, thereby analyzing the components perpendicular to the ground and parallel to the ground.

[0142] A3. By analyzing the additional walking resistance generated by the interaction between the cutting blades and vegetation when the lawnmower is mowing, we can analyze the changes in walking speed caused by load changes, introduce the additional resistance of the mowing operation, and finally output the total walking resistance.

[0143] The calculation formula for the walking resistance unit is as follows:

[0144] ;

[0145] in:

[0146] FR stands for Total Travel Resistance, which is the total driving force required for the lawnmower to overcome ground friction, the gravity component of the slope, and the additional resistance of the mowing operation during operation. The unit is Newton. This value is the core input parameter of the entire control system and directly determines the power output requirements of the subsequent hydraulic system.

[0147] Total walking resistance is a unified quantification of the external environmental conditions (terrain, slope, speed and workload) of the lawnmower into a single value, enabling the electronic control system to sense the current workload and is the basis for intelligent power matching. In agricultural scenarios, the terrain and vegetation density of lawn mowing operations change frequently, and real-time acquisition of total walking resistance allows the system to automatically adapt to different fields and grass conditions.

[0148] Explain the rationality of the dimensions of this unit:

[0149] The dimensions are: dimensionless × kg × m / s 2 × dimensionless = N;

[0150] The dimensions are: kg × m / s 2 × dimensionless = N;

[0151] The dimension of FRR is N;

[0152] In conclusion, the dimensions of this unit are reasonable;

[0153] F1 refers to the ground rolling resistance coefficient, a dimensionless coefficient characterizing the degree of rolling friction between the track and the ground. Its value depends on the ground type and soil condition. This embodiment presets typical value ranges as follows: flat grassland 0.08-0.12, muddy ground 0.20-0.30, gravelly ground 0.15-0.25, and sandy ground 0.25-0.35. This value can be indirectly obtained through a ground type intelligent recognition module. The workflow of this module is as follows:

[0154] An ultrasonic terrain scanning sensor and a soil moisture sensor are installed at the front of the lawnmower chassis to collect ground undulation features and soil moisture content, respectively. The collected ground feature data (undulation frequency, amplitude, and soil moisture value) are input into a lightweight ground classification model (based on a decision tree algorithm, with training samples covering common agricultural terrains such as grassland, mud, gravel, and sandy soil) in the PLC. The model outputs the current ground type, and the PLC outputs the corresponding ground rolling resistance coefficient F1 value according to the built-in lookup table mapping relationship.

[0155] The ground rolling resistance coefficient F1 is one of the most important terrain parameters in the calculation of walking resistance. In agricultural mowing operations, the same plot of land may contain both flat grassland and low-lying muddy areas. By intelligently identifying the ground type and dynamically adjusting the ground rolling resistance coefficient F1 value, the system can automatically match the walking resistance characteristics of different sections, avoiding getting stuck in muddy areas due to insufficient power, or wasting energy due to excessive power on hard surfaces.

[0156] m refers to the total mass of the mower in operation, which includes the weight of the machine body, engine, hydraulic system, cutting mechanism, and hydraulic oil. The unit is kilograms. It is a fixed parameter calibrated by the factory and stored in the PLC. The total mass of the machine is one of the basic sources of travel resistance. The greater the mass, the greater the rolling resistance and slope resistance. This parameter provides the system with basic load information of the equipment itself.

[0157] g refers to the acceleration due to gravity, i.e., the gravitational acceleration constant at the Earth's surface, with a value of 9.8 m / s². 2 , is a fundamental physical constant used to convert mass into gravity, and is an indispensable benchmark quantity in calculating ramp resistance and stability analysis;

[0158] θ refers to the ground slope angle, which is the angle between the direction of the lawnmower's movement and the horizontal plane. The unit is degrees. A positive value indicates an uphill slope, and a negative value indicates a downhill slope. It can be directly collected by an inclination sensor installed at the geometric center of the lawnmower chassis. The sensor outputs a digital signal, which is then transmitted to the PLC controller. The slope angle directly determines the distribution of the lawnmower's gravity component on the slope. When going uphill, the component of gravity along the slope becomes part of the walking resistance, and when going downhill, it becomes part of the driving force. In agricultural scenarios such as hilly and mountainous areas, the slope changes frequently and with large amplitude. Real-time acquisition of the slope angle is the prerequisite for the system to realize adaptive power adjustment on the slope, avoiding insufficient power when going uphill or speed loss when going downhill.

[0159] The introduction of cosθ and sinθ is to decompose gravity into two directions: perpendicular and parallel to the ground. When the lawnmower travels on a slope with an angle of θ, the gravity m×g is no longer perpendicular to the ground, but makes an angle θ with the direction normal to the ground. At this time:

[0160] The component perpendicular to the ground: m×g×cosθ, this component determines the normal force of the track on the ground, and the magnitude of the rolling resistance is proportional to the normal force, so cosθ is introduced;

[0161] The component parallel to the ground: This component is the part of gravity along the slope. When going uphill, it becomes part of the walking resistance (hindering progress), and when going downhill, it becomes part of the walking driving force (propelling progress). Therefore, sinθ is introduced.

[0162] FRR refers to the additional resistance during lawn mowing, which is the extra resistance generated by the interaction between the cutting blades and the vegetation when the lawnmower starts its cutting mechanism. The unit is Newtons (N). This resistance varies with vegetation density, height, water content, and cutting width. It can be indirectly calculated using a torque sensor on the cutting mechanism. The specific method is as follows:

[0163] First, a torque sensor is installed on the cutting disc drive shaft to collect the torque Tc (N·m) consumed by the cutting mechanism in real time.

[0164] Then, combined with the cutting disc rotation speed nc (r / min), the cutting power pc = (Tc × nc) ÷ 9550 is calculated. The coefficient 9550 is a unit conversion constant, which comes from the unit conversion relationship between power, torque and rotation speed.

[0165] Subsequently, according to the principle of energy conservation, a portion of the cutting power is converted into additional resistance during walking: FRR = (pc × pfd) ÷ FV, where pfd is the efficiency coefficient of the transfer of cutting power to walking resistance, and FV refers to the walking speed. In this embodiment, the preset value range is 0.3-0.6. Additional resistance during mowing is a key parameter that distinguishes between unloaded walking and working walking. When the mower is only moving between sites, the additional resistance FRR during mowing is close to zero. When the cutting mechanism is started for operation, the additional resistance FRR during mowing increases significantly. This parameter enables the system to automatically identify whether it is currently in working state and adjust the walking power output accordingly. During mowing, the displacement is automatically increased to compensate for the additional resistance, avoiding a sudden drop in walking speed due to a sudden increase in load, and ensuring the uniformity and continuity of mowing operations. In agricultural mowing operations, the vegetation density and height vary greatly. Real-time acquisition of additional resistance FRR during mowing is an important means to achieve precise power matching.

[0166] In this embodiment, the core contribution of the walking resistance unit lies in transforming the external environmental state of the lawnmower into a quantitative value that can be recognized by the electronic control system. The total walking resistance FR is not a physical quantity that can be directly measured by a single sensor; it is the result of the combined effects of multiple factors, including ground characteristics (rolling resistance coefficient), terrain conditions (slope angle), equipment weight (total machine mass), and workload (additional resistance from mowing). By unifying this heterogeneous information into a force dimension, the walking resistance unit enables the electronic control system to sense external loads.

[0167] The walking resistance unit contributes to the system on three levels. First, it establishes a mapping relationship from environmental parameters to mechanical parameters, enabling previously independent subsystems such as ground type identification, slope detection, and cutting load monitoring to work collaboratively within a unified framework. Second, it makes the calculation of walking resistance real-time. Whenever any input parameter changes (such as moving from flat grass to muddy areas, increasing slope, or starting the cutting mechanism), the total walking resistance FR will be dynamically updated, providing timely basis for subsequent displacement adjustment. Third, as the data entry point for the entire three-level progressive algorithm, it determines the basis for all subsequent calculations. If the calculation of the total walking resistance FR is inaccurate, the inputs of the closed-loop pump discharge unit and the walking stability integrated unit will deviate, affecting the accuracy of the entire control system.

[0168] The total resistance FR is the output of the sensing layer of the entire control system. Its substantial role in the system is to provide a basis for all subsequent control decisions. Specifically:

[0169] The total resistance (FR) determines whether the system can accurately identify the load level of the current working condition. When the total resistance (FR) is small, the system judges that it is currently in a light load state (flat road surface, unloaded travel). At this time, there is no need to output a large displacement to avoid energy waste. When the total resistance (FR) is large, the system judges that it is currently in a heavy load state (uphill, muddy ground, mowing operations). At this time, it is necessary to increase the displacement to provide sufficient driving force. Without the total resistance (FR), the system can only passively respond to the instructions of the operating handle and cannot distinguish between the two fundamentally different situations: the operator needs to accelerate and the speed decreases due to increased load.

[0170] Please refer to Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 The treatment process of the closed-loop pump discharge unit is as follows:

[0171] The calculation formula for the closed-loop pump discharge unit is as follows:

[0172] B1. By introducing the pitch circle radius of the drive wheel and combining it with the total travel resistance, we can analyze the required driving torque on the drive wheel.

[0173] B2. By analyzing the ratio of output power to input hydraulic power after mechanical friction loss in the travel motor, the degree of energy loss due to internal friction of the motor can be reflected, so as to introduce the mechanical efficiency of the travel motor.

[0174] B3. By analyzing the ratio of the actual output flow rate to the theoretical input flow rate of the travel motor, the degree of internal leakage loss of the motor can be reflected, so as to introduce the volumetric efficiency of the travel motor.

[0175] B4. By analyzing the pressure difference between the oil outlet and return port of the closed pump, the relationship between the working pressure difference and the actual load of the hydraulic system is quantified, so as to introduce the working pressure difference of the hydraulic system.

[0176] B5. By analyzing the transmission ratio of the reduction mechanism between the output shaft of the travel motor and the drive wheel, the amplification factor of the output torque of the travel motor when it is transmitted to the drive wheel is quantified, so as to introduce the transmission ratio between the drive wheel and the motor.

[0177] B6. By analyzing the dynamic synergistic relationship between the current temperature and viscosity of hydraulic oil, the temperature-viscosity synergistic weighting coefficient, real-time oil temperature, optimal working temperature of hydraulic oil, and kinematic viscosity at the current temperature are combined and calculated to output the hydraulic oil temperature-viscosity synergistic coefficient.

[0178] ;

[0179] in:

[0180] VG refers to the target displacement of the closed-loop pump, which is the target displacement value that the closed-loop pump should output, calculated by the electronic control system based on the current travel resistance and hydraulic system status. The unit is milliliters per revolution (ml / r). This value is directly used as the control target of the electro-proportional valve. The PLC controller outputs a signal based on this to drive the electro-proportional valve to adjust the swashplate angle of the closed-loop pump so that the actual displacement is close to the target displacement.

[0181] The target displacement (VG) of the closed-loop pump is the core bridge connecting the sensing layer and the execution layer. It transforms the mechanical quantity of travel resistance into the control quantity of the hydraulic system, enabling the closed-loop pump to supply oil on demand. When the resistance is high, the displacement is increased to output more hydraulic power, and when the resistance is low, the displacement is reduced to avoid energy waste. In agricultural mowing operations, the complexity of field terrain and grass conditions requires the power system to have a fast response capability. The real-time calculation of the target displacement (VG) of the closed-loop pump enables the system to complete the closed loop from sensing load changes to adjusting power output in milliseconds.

[0182] Coefficient 10 6 This is a unit conversion factor, and its reason for existence is that when the hydraulic system working pressure difference VGC in the formula is in Pa, the unit of the calculated result is m. 3 / r, but in actual engineering, the discharge capacity of closed-loop pumps is expressed in ml / r, so m needs to be converted to m. 3 Convert to ml (1m) 3 =10 6 ml);

[0183] rd refers to the pitch circle radius of the drive wheel, that is, the pitch circle radius at the point where the track drive wheel meshes with the track, and the unit is meters (m). This parameter determines the lever arm length for converting the motor output torque into track traction force. The drive wheel radius is the lever arm for converting torque into traction force. The larger the radius, the smaller the traction force generated under the same motor torque, and a larger pump displacement is required to compensate.

[0184] FR×rd×2π represents the total resistance to travel FR × the pitch circle radius of the drive wheel rd, which gives the required driving torque (N·m) on the drive wheel. Since force multiplied by lever arm equals torque, the drive wheel needs to overcome the resistance to travel FR to roll forward, and a traction force equal to FR needs to be applied to its rim. The lever arm of this force relative to the wheel center is rd. Therefore, the required driving torque is FR×rd, and 2π is the number of radians per revolution. Thus, the overall meaning of this numerator is the mechanical power required for the drive wheel to overcome the resistance to travel (expressed in the form of energy required per revolution).

[0185] VGA refers to the mechanical efficiency of the travel motor, which is the ratio of the output power after mechanical friction loss inside the travel motor to the input hydraulic power. It is dimensionless. In this embodiment, the preset value range is 0.90-0.95. Mechanical efficiency reflects the degree of energy loss due to internal friction of the motor (such as piston and cylinder, distributor plate, etc.). The higher the efficiency, the greater the mechanical power output under the same hydraulic power, and the smaller the required pump displacement.

[0186] VGB refers to the volumetric efficiency of the travel motor, which is the ratio of the actual output flow to the theoretical input flow of the travel motor. It is dimensionless, and in this embodiment, the preset value range is 0.92-0.97. The volumetric efficiency is mainly affected by the internal leakage of the motor. The volumetric efficiency reflects the degree of loss due to internal leakage of the motor. The higher the efficiency, the less leakage, and the higher the output speed under the same input flow. The volumetric efficiency is intrinsically related to the temperature viscosity effect in the hydraulic oil temperature viscosity coefficient VGS. When the oil temperature rises, the viscosity decreases, the leakage increases, and the volumetric efficiency decreases. This is also the necessity of the existence of the travel motor volumetric efficiency VGB.

[0187] VGC refers to the working pressure difference of the hydraulic system, which is the pressure difference between the outlet and return ports of the closed pump. It is the actual working pressure difference of the hydraulic system, and the unit is Pascal. Pressure sensors can be installed at the outlet and return ports of the closed pump. The PLC collects the pressure values ​​at the two points through the analog input module and calculates the difference. The working pressure difference is a direct reflection of the actual load of the hydraulic system. When the lawnmower encounters greater walking resistance, the system pressure increases and the working pressure difference VGC of the hydraulic system increases, and vice versa. In the displacement calculation formula, the working pressure difference VGC of the hydraulic system is in the denominator. The higher the pressure, the smaller the displacement required to achieve the same output power, which is consistent with the actual physical process.

[0188] VGCmin refers to a small positive number (such as 0.5MPa) to avoid division by zero or numerical explosion;

[0189] VGD refers to the transmission ratio between the drive wheel and the motor, that is, the transmission ratio of the reduction mechanism between the output shaft of the travel motor and the drive wheel. It is dimensionless. If the motor directly drives the drive wheel, VGD is 1. If it is transmitted through a reducer, VGD is the reduction ratio (e.g., VGD of 2 means that the drive wheel rotates 1 revolution for every 2 revolutions of the motor). The transmission ratio determines the amplification factor of the motor output torque when it is transmitted to the drive wheel. The larger the transmission ratio, the greater the torque obtained by the drive wheel under the same motor torque, and the smaller the required pump displacement.

[0190] The mechanical efficiency VGA of the travel motor × the volumetric efficiency VGB of the travel motor represents the total efficiency of the travel motor, which is the product of mechanical efficiency and volumetric efficiency. In the process of converting hydraulic power into mechanical power, some energy is lost due to friction and leakage. The efficiency term in the denominator is used to compensate for this loss. The lower the efficiency, the smaller the denominator, and the larger the required displacement. Therefore, the overall meaning of this term is to reverse the mechanical power demand at the motor output end to the product of the flow rate and pressure required at the hydraulic system input end, and then make corrections based on the transmission ratio.

[0191] The numerator (mechanical power required for the drive wheel) of this unit is divided by the denominator (product of hydraulic system efficiency and pressure parameters) to obtain the target displacement that the closed pump needs to output to meet the current travel resistance. This is then multiplied by the hydraulic oil temperature-viscosity coefficient VGS to feedforward compensation for volumetric efficiency deviation caused by oil temperature changes.

[0192] VGS refers to the hydraulic oil temperature-viscosity coefficient, a dimensionless correction coefficient that characterizes the dynamic relationship between the current temperature and viscosity of hydraulic oil. Its value ranges from 0.85 to 1.15. When the oil temperature is at the optimal operating temperature, VGS = 1. When the oil temperature rises, VGS > 1, and the displacement needs to be increased to compensate for leakage losses. When the oil temperature is low, VGS < 1, and the displacement can be appropriately reduced to take advantage of the high volumetric efficiency brought by high viscosity.

[0193] The core value of the hydraulic oil temperature-viscosity synergy coefficient (VGS) lies in transforming the passive response to the volumetric efficiency decline caused by oil temperature changes into active compensation. In agricultural mowing operations, after several hours of continuous operation in high summer temperatures, the hydraulic oil temperature may rise from 20°C during cold start to over 80°C, and the oil viscosity may decrease by several times, resulting in a significant increase in internal leakage of the motor. If no compensation is made, the walking speed will become slower and slower at the same handle position. The hydraulic oil temperature-viscosity synergy coefficient (VGS) predicts this trend in advance through the temperature-viscosity synergy relationship and actively increases the displacement to maintain a constant walking speed, so that the operator does not need to frequently adjust the handle position, thus improving the comfort and consistency of agricultural operations.

[0194] In existing technologies, hydraulic system oil temperature control usually adopts a threshold triggering method, which activates the cooler when the oil temperature exceeds the set value, which is a passive protection. However, the hydraulic oil temperature viscosity coefficient (VGS) introduces the coupling relationship between oil temperature and viscosity into the feedforward channel of displacement calculation, enabling the system to actively adjust the displacement before the oil temperature change causes a significant performance degradation, thus achieving a leap from post-remediation to pre-compensation.

[0195] Furthermore, the formula for calculating the hydraulic oil temperature-viscosity synergy coefficient (VGS) is as follows:

[0196] ;

[0197] In the above formula:

[0198] kt refers to the temperature-viscosity synergy weighting coefficient, which is used to adjust the influence of the temperature-viscosity synergy effect in displacement compensation. It is dimensionless, and in this embodiment, the preset value range is 0.01-0.05. It can be determined through calibration tests. Specifically, the hydraulic system can be run at different oil temperatures on a test bench, and the deviation between the actual speed and the target speed can be measured. The optimal kt value can be obtained by fitting with the least squares method. The temperature-viscosity synergy weighting coefficient kt determines the intensity of temperature-viscosity compensation. The larger the coefficient, the more aggressive the compensation; the smaller the coefficient, the more conservative the compensation. A reasonable temperature-viscosity synergy weighting coefficient kt value needs to achieve a balance between the compensation effect and the system stability.

[0199] TT refers to the real-time oil temperature, which is the real-time temperature of the hydraulic oil at the return port of the hydraulic system, in degrees Celsius. It can be collected by a temperature sensor installed at the return port of the hydraulic oil tank. The signal is converted into a standard signal by a temperature transmitter and then input into the PLC analog module. The real-time oil temperature TT is the core input variable for calculating the hydraulic oil temperature-viscosity coefficient (VGS), reflecting the thermal state of the hydraulic system. Changes in oil temperature directly change the physical properties (viscosity) of the oil, thereby affecting the volumetric efficiency and response characteristics of the entire hydraulic system.

[0200] TT0 refers to the optimal operating temperature of the hydraulic oil, which is the reference temperature at which the hydraulic oil reaches its optimal viscosity and lubrication performance. In this embodiment, it is preset to 55°C, but can be determined according to the recommended value of the hydraulic oil supplier and the system calibration results. This parameter serves as the benchmark point for temperature-viscosity compensation. When the actual oil temperature deviates from this benchmark, the system activates the compensation mechanism.

[0201] VV0 refers to the kinematic viscosity at the optimal operating temperature, i.e., the kinematic viscosity of the hydraulic oil at the optimal operating temperature TT0, and is measured in millimeters squared per second (mm²). 2 ( / s), which can be determined based on the viscosity-temperature characteristics data provided by the hydraulic oil supplier. This parameter serves as a benchmark reference value for viscosity changes and is used to calculate the relative change in viscosity when the oil temperature deviates from the optimal value.

[0202] VT refers to the kinematic viscosity at the current temperature, that is, the kinematic viscosity of the hydraulic oil at the current real-time oil temperature TT, and the unit is millimeters squared per second (mm). 2 The viscosity-temperature characteristic (VT) value can be obtained by looking up a table preset in the PLC. The table data comes from the standard viscosity-temperature curve provided by the hydraulic oil supplier, covering the range from -20℃ to 100℃. The PLC obtains the corresponding VT value by looking up the table based on the current real-time oil temperature TT. The introduction of VT reflects the flow characteristics of the oil at the current temperature. The higher the viscosity, the stronger the oil film carrying capacity but the greater the flow resistance. The lower the viscosity, the smaller the flow resistance but the greater the leakage loss. The calculation of VV0÷VT quantifies the degree of influence of oil temperature change on volumetric efficiency.

[0203] In this embodiment, the core contribution of the closed-loop pump discharge unit is to transform the mechanical requirement of walking resistance into control commands for the hydraulic system. The total walking resistance FR is the amount of force required to push the lawnmower, while the closed-loop pump target displacement VG is the amount of displacement the closed-loop pump needs to output to provide this force. The closed-loop pump discharge unit completes the transformation from the demand side to the supply side and is a bridge between perception and execution.

[0204] The closed-loop pump discharge unit contributes to the system in three ways. First, it enables power supply on demand, so that the pump's displacement no longer depends on manual adjustment or fixed gear mapping by the operator, but is automatically matched according to the actual load. Second, it introduces a temperature-viscosity synergy coefficient, incorporating the impact of hydraulic oil temperature changes on system performance into the feedforward channel of displacement calculation, enabling the system to actively adjust the displacement before the volumetric efficiency decays due to oil temperature changes, thus maintaining the stability of power output. Third, the output closed-loop pump target displacement VG is directly used as the control target of the electro-proportional valve, enabling the PLC controller to output precise signals to drive the electro-proportional valve to operate, achieving seamless connection from calculation to execution.

[0205] The target displacement VG of the closed-loop pump is the execution-level target of the entire control system. Its substantial role in the system is to transform the sensing results into specific control commands. Specifically:

[0206] The target displacement VG of the closed-loop pump directly determines the opening degree of the electro-proportional valve, which in turn determines the swashplate angle and actual output displacement of the closed-loop pump. The value of the target displacement VG of the closed-loop pump is converted into a signal by the PLC controller to drive the electro-proportional valve, so that the actual displacement of the closed-loop pump approaches the target displacement. This process is a millisecond-level closed-loop regulation, which ensures the real-time response of power output.

[0207] After the target displacement VG of the closed pump is corrected by the hydraulic oil temperature viscosity coefficient VGS, it has temperature self-adaptive capability. When the hydraulic oil temperature rises, VGS>1, and V_g increases accordingly to compensate for the volumetric efficiency reduction caused by the decrease in viscosity. When the oil temperature drops, VGS<1, and V_g decreases accordingly. Utilizing the high efficiency brought by high viscosity, this correction enables the system to maintain stable walking performance under different thermal conditions such as cold start and long-term operation.

[0208] Please refer to Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 The processing flow of the walking stability integrated unit is as follows:

[0209] C1. By analyzing the vertical height of the lawnmower's center of gravity relative to the ground, the relationship between the center of gravity height and the risk of tipping over is quantified, thus introducing the overall center of gravity height.

[0210] C2. Analyze the turning radius of the lawnmower when it turns. It is obtained by combining the rotation speeds of the left and right motors. The turning radius is the key to the source of centrifugal force in the stability determination.

[0211] C3. By analyzing the horizontal distance between the longitudinal centerlines of the left and right tracks, the relationship between track center distance and stability is analyzed, thus introducing track center distance.

[0212] C4. By analyzing the synergistic relationship between the non-uniformity of the track ground pressure distribution and the proportion of the actual bearing area, and combining the maximum specific pressure of the track ground pressure, the average specific pressure of the track ground pressure, the actual bearing area, and the total area of ​​the track ground pressure, a dynamic distribution coefficient of track ground pressure is introduced to finally output the lateral stability coefficient. The lateral stability coefficient is then combined with the compensation strength coefficient and the target displacement of the closed pump to output the corrected target displacement.

[0213] The calculation formula for the walking stability integrated unit is as follows:

[0214] ;

[0215] ;

[0216] in:

[0217] KS refers to the lateral stability coefficient, a dimensionless coefficient that characterizes the lateral stability of the lawnmower under the current working conditions. KS < 1 indicates that it is in a safe and stable state. The closer KS is to 0, the safer it is. KS ≥ 1 indicates that there is a risk of tipping over, and the system needs to intervene immediately to slow down or issue an alarm.

[0218] The lateral stability coefficient KS quantifies the lawnmower's posture (lateral slope), motion state (speed, turning radius), force state (travel resistance), and track-ground contact state (specific pressure distribution) into a single value. When the lateral stability coefficient KS approaches the critical value, the system automatically reduces the displacement to slow down, preventing the operator from accidentally causing the lawnmower to tip over on slopes or soft soil due to lack of experience or obstructed vision (such as dense vegetation). In agricultural lawnmowing operations in hilly and mountainous areas, tipping over is one of the most common safety accidents. The introduction of the lateral stability coefficient KS enables the system to have active anti-tip-over capability, significantly improving the safety of agricultural operations.

[0219] VGa refers to the corrected target displacement, which is the final output of the closed-loop pump target displacement value to the electro-proportional valve after stability compensation correction. The unit is milliliters per revolution (ml / r). This value is the final output result of the entire three-level progressive algorithm unit, which directly drives the actuator and is the final instruction of the entire algorithm system. It unifies the results of the three-level progressive steps of walking resistance perception (walking resistance unit), power matching calculation (closed-loop pump discharge unit), and stability safety correction (walking stability integrated unit) into a single control quantity. When the stability is good, VGa≈VG, and the system outputs according to the optimal power matching. When the stability is insufficient, VGa<VG, and the system actively reduces the power output to decelerate, ensuring safety first. This mechanism enables the lawnmower to automatically achieve a balance between efficiency and safety in complex agricultural terrain operations without the need for the operator to constantly monitor slope changes and manually decelerate.

[0220] VGmin is the minimum allowable displacement (such as 0 or a very small positive value) to avoid negative displacement.

[0221] R1 refers to the compensation strength coefficient, which is a weighting coefficient used to adjust the stability compensation strength. It is dimensionless and ranges from 0.1 to 0.3. The larger R1 is, the more aggressive the stability correction and the greater the deceleration. The smaller R1 is, the more moderate the correction. It can be determined through calibration tests. Taking into account both safety and work efficiency, the optimal R1 value is determined in the test and written into the PLC program. It can also be set as a user-adjustable parameter, allowing operators to fine-tune it according to their own experience and safety requirements. It determines the weight of the lateral stability coefficient KS on the final displacement. A reasonable compensation strength coefficient R1 value should ensure that sufficient deceleration can be achieved when the lateral stability coefficient KS is close to 1 to avoid rollover, while not excessively restricting work efficiency when the lateral stability coefficient KS is small.

[0222] KSH refers to the center of gravity height of the entire machine, which is the vertical height of the center of gravity of the lawnmower relative to the ground, measured in meters. This parameter depends on the mass distribution of the entire machine, including the arrangement of components such as the engine, hydraulic system, cutting mechanism, and fuel tank. It is a factory-calibrated parameter and can be determined through 3D modeling or actual weighing. It is written into the PLC program. The center of gravity height is the most critical geometric parameter in stability analysis. The higher the center of gravity, the greater the overturning moment generated under the same lateral acceleration, and the higher the risk of tipping over. In lawnmower design, the power source and hydraulic system are usually located on the upper part of the chassis, resulting in a higher center of gravity. Therefore, real-time monitoring and compensation of KSH is particularly important.

[0223] KSR refers to the turning radius, which is the radius of the arc drawn by the geometric center of the lawnmower when it turns, measured in meters. The smaller the turning radius KSR, the sharper the turn and the greater the centrifugal force. It can be calculated based on the speed difference between the two travel motors. The specific method is as follows:

[0224] By using speed sensors installed on the output shafts of the walking motors on both sides, the speeds of the left motor (KSRa) and the right motor (KSRb) are collected respectively. Then, the track speeds on both sides are calculated as vl = (KSRa × 2π × rd) ÷ (60 × VGD) and vr = (KSRb × 2π × rd) ÷ (60 × VGD). After that, the turning radius is calculated as: KSR = (KSB ÷ 2) × [(vr + vl) ÷ (vr - vl)], where KSB is the track center distance. The turning radius is a key parameter for determining the source of centrifugal force in stability assessment. The smaller the turning radius (the sharper the turn), the greater the centrifugal force generated at the same speed, and the higher the risk of rollover. In agricultural scenarios, obstacles such as field boundaries and tree barriers often require small-radius turns. At this time, the system needs to automatically limit the speed according to the turning radius KSR to avoid rollover due to sharp turns.

[0225] In The lateral slope angle is collected by a lateral tilt sensor. The first term represents the overturning moment generated by the component of the machine's weight on the lateral slope, and the denominator contains... It represents the contribution of the effective weight on the lateral slope to the stabilizing moment, and the independent lateral slope angle is introduced in the walking stability integrated unit, which is fundamentally different from the forward slope angle θ in the walking resistance unit.

[0226] KSB refers to the track center distance, which is the horizontal distance between the longitudinal center lines of the left and right tracks, in meters. The track center distance is the lever arm for resisting rollover in stability analysis. The wider the center distance, the stronger the ability to resist rollover under the same overturning moment. This parameter is a denominator term, reflecting the natural advantage of tracked vehicles in lateral stability compared to wheeled vehicles.

[0227] In this equation, m×g represents the total weight of the lawnmower, which is the stabilizing force source against tipping. The greater the weight, the less likely it is to tip over. Half the track center distance KSB, which is half the track center distance, means that when the lawnmower is about to tip over on a transverse ramp, the body will rotate around the grounding line of the outer track. The horizontal distance from the center of gravity to this rotation axis is KSB÷2 (assuming the center of gravity is located on the longitudinal center axis). This distance is equivalent to the lever arm against tipping. The longer the lever arm, the stronger the ability to resist tipping. Therefore, the overall meaning of the denominator of this unit is the maximum tipping moment generated by the weight of the lawnmower itself on the transverse ramp, that is, the maximum tipping moment that the body can withstand without tipping over.

[0228] KSN refers to the dynamic distribution coefficient of track ground pressure, a dimensionless correction coefficient that characterizes the synergistic relationship between the non-uniformity of the track ground pressure distribution and the proportion of the actual bearing area. Its value ranges from 0.7 to 1.3. On an ideal flat hard road surface, the pressure distribution is uniform and the bearing area is sufficient, so KSN≈1. On gravel or undulating ground, the pressure distribution is uneven and part of the track is suspended, so KSN>1, and the stability judgment is more stringent.

[0229] The core value of the Track Ground Pressure Dynamic Distribution Coefficient (KSN) lies in breaking the ideal assumption of uniform ground pressure distribution in the traditional stability analysis of tracked vehicles. It introduces the actual contact state between the track and the ground into the stability assessment. In agricultural mowing operations, the field surface is often uneven, with gravel, furrows, potholes, etc., which can cause the track to be partially suspended. At this time, the actual bearing area may only be 60%-80% of the total area, and the pressure is concentrated under a few support rollers. If the stability is still calculated based on the ideal uniform distribution, the actual safety margin will be seriously overestimated. The Track Ground Pressure Dynamic Distribution Coefficient (KSN) corrects the stability coefficient through the synergistic analysis of the non-uniformity of the pressure distribution and the proportion of the actual bearing area. The more uneven the ground and the more serious the track suspension, the larger the Track Ground Pressure Dynamic Distribution Coefficient (KSN) is, the more stringent the stability assessment, and the earlier the system intervenes to decelerate, thereby effectively preventing rollover accidents.

[0230] In existing technologies, ground pressure is usually regarded as a static parameter in the design stage of tracked vehicles, used for selection and structural strength verification, and has not been introduced into the walking control system as a dynamic control variable. The innovation of the dynamic distribution coefficient of track ground pressure KSN is to activate this static design parameter and perform synergistic coupling analysis with the actual bearing area, so that the stability judgment is improved from the assumed ideal state to the actual contact state.

[0231] The formula for calculating the dynamic distribution coefficient of track ground pressure KSN is as follows:

[0232] ;

[0233] In the above formula:

[0234] W1 refers to the specific pressure bearing capacity synergistic weighting coefficient, which is a weighting coefficient used to adjust the synergistic influence of the degree of non-uniformity of specific pressure distribution and the proportion of actual bearing area in stability correction. It is dimensionless and ranges from 0.1 to 0.5. It can be determined through calibration tests. Specifically, the lawnmower is turned at different speeds on different ground types (flat hard road, gravel ground, undulating ground), and the deviation between the actual rollover critical state and the theoretical calculation value is recorded. The optimal W1 value is determined by comparative analysis and written into the PLC program. The specific pressure bearing capacity synergistic weighting coefficient W1 determines the correction strength of the grounding state on the stability judgment. The larger the coefficient, the more significant the influence of the track grounding state on the stability judgment. The smaller the coefficient, the more conservative the correction. A reasonable specific pressure bearing capacity synergistic weighting coefficient W1 value needs to be balanced between safety sensitivity and false alarm rate.

[0235] WA refers to the maximum specific pressure of the track ground contact section, which is the maximum pressure value among all measuring points within the track ground contact section, measured in Pascals. This value usually appears at the track plate directly below the support roller and can be directly collected by a thin-film pressure sensor array. The PLC compares the values ​​of all measuring points and takes the maximum value. The introduction of this parameter reflects the degree of pressure concentration in the track ground contact section. On gravel ground, the track plate under the support roller may bear extremely high local pressure, while the adjacent area is almost unaffected. The larger the difference between WA and WB, the more uneven the specific pressure distribution and the worse the actual stability.

[0236] WB refers to the average specific pressure of the track grounding section, which is the arithmetic mean of the pressure at all measuring points in the track grounding section. The unit is Pascal. It is obtained by summing the pressure values ​​at all measuring points by the PLC and then dividing by the number of measuring points. The average specific pressure WB of the track grounding section reflects the average load level of the track grounding section. Under ideal uniform grounding conditions, WA≈WB, and under non-uniform grounding conditions, WA>WB. The relative difference between the two (WA-WB)÷WB directly quantifies the degree of non-uniformity of the specific pressure distribution.

[0237] WC refers to the actual bearing area, which is the effective area of ​​the track ground contact section that actually contacts the ground and bears pressure. The unit is square meters. On an ideal flat ground, WC≈WD. On undulating ground, where some track plates are suspended, WC<WD. It can be calculated based on the data collected by the thin-film pressure sensor array. The number of measurement points with a pressure value greater than the set threshold (such as 0.1MPa, used to exclude sensor noise and very slight contact) is multiplied by the area represented by a single measurement point. The actual bearing area WC reflects the actual contact degree between the track and the ground. The smaller the actual bearing area, the greater the bearing pressure per unit area, the easier it is for the track to sink, and the weaker the lateral grip. It is also easier to slip or roll over on slopes or when turning.

[0238] WD refers to the total contact area of ​​the track, which is the nominal total area of ​​the track in contact with the ground. It is calculated by multiplying the track's contact length by the width of the track pads, and is expressed in square meters. It serves as a reference for the actual load-bearing area. This reflects the proportion of tracks that are suspended or ineffectively in contact with the ground. The larger the value, the more uneven the ground and the worse the actual stability.

[0239] In this embodiment, the core contribution of the walking stability integrated unit is to provide a safety fallback mechanism for the entire walking system. The goal of the first two formulas is to make the lawnmower walk well and match the power according to the load, while the goal of the walking stability integrated unit is to make the lawnmower walk safely and actively intervene when the stability is insufficient to prevent rollover accidents.

[0240] Specifically, the walking stability integrated unit contributes to the system in three ways;

[0241] It elevates lateral stability from operator experience-based judgment to quantitative calculation by the system. Through the dimensionless coefficient KS, the lawnmower's attitude, motion state, and track ground contact state are uniformly quantified, enabling the system to objectively assess the safety of the current working conditions.

[0242] The introduction of a dynamic distribution coefficient for grounding specific pressure breaks the ideal assumption of uniform distribution of grounding specific pressure in traditional stability analysis, making stability judgment closer to actual working conditions. On uneven ground, the system can identify risks and intervene earlier.

[0243] The corrected target displacement VGa output directly overwrites the closed pump target displacement VG of the closed pump discharge unit as the final execution command, realizing the safety-first control logic. When the stability is insufficient, no matter how the operator operates the handle, the system will actively reduce the displacement to slow down, fundamentally avoiding safety accidents caused by operational errors or lack of experience.

[0244] The lateral stability coefficient KS is the safety assessment output of the entire control system, and the corrected target displacement VGa is the final execution command. Together, they constitute the system's safety fallback mechanism. The lateral stability coefficient KS quantifies the lawnmower's lateral stability into a comparable value, enabling the system to objectively determine whether the current working condition is safe. The calculation of the lateral stability coefficient KS integrates multiple factors such as walking resistance, center of gravity height, lateral slope, walking speed, turning radius, track center distance, and track ground contact status, making it a multi-dimensional safety assessment indicator.

[0245] Example 2:

[0246] Please see Figures 1 to 5 This embodiment provides a basic electronically controlled closed-loop pump hydraulic drive walking system:

[0247] This embodiment is a basic implementation of the hydraulic drive walking technology for tracked heavy-duty lawnmowers, suitable for heavy-duty lawnmowing operations in conventional complex terrain (hills, embankments). The specific structure and implementation details are as follows:

[0248] 1. Core component selection and parameters:

[0249] (1) Closed-loop pump: Two variable displacement piston closed-loop pumps are selected, each with a displacement of 11.7 ml / r, which control the left and right walking motors respectively. The rated working pressure is 16 MPa and the rated speed is 3600 r / min. Equipped with an electro-proportional control valve, the displacement can be precisely adjusted through the electronic control system, and the response time is ≤0.1s.

[0250] (2) Walking motor: A cycloidal hydraulic motor, model ZBMA-250, is selected. The rated working pressure is 20MPa, the rated speed is 1500r / min, and the output torque is 250N·m. It is suitable for the power requirements of heavy-duty lawn mowers and has a bidirectional rotation function, which can realize the forward and backward movement of the equipment.

[0251] (3) Electro-proportional valve: A four-way electro-proportional valve assembly is selected, with a maximum working pressure of 40 bar, which is suitable for closed pumps.

[0252] (4) Electrical control system: It adopts a PLC controller and is equipped with an operating handle, speed sensor and pressure sensor. It can collect hydraulic system pressure and walking speed signals in real time to realize closed-loop control with an adjustment accuracy of ±0.1km / h;

[0253] (5) Auxiliary components: hydraulic oil tank (capacity 20L), suction filter element (filtration accuracy 100μm), suction and return oil integrated filter (suction filtration accuracy 80μm, return oil filtration accuracy 10μm), cooler (air-cooled, heat dissipation power 4kW), hydraulic pipeline.

[0254] 2. System Connection and Layout:

[0255] The power input end of the closed-loop pump is connected to the output shaft of the lawnmower's engine via a coupling. Port A of the closed-loop pump is connected to the oil inlet of the travel motor via a high-pressure oil pipe, and the oil outlet of the travel motor is connected to Port B of the closed-loop pump via a high-pressure oil pipe, forming a closed hydraulic transmission circuit. The closed-loop pump integrates an overflow valve to prevent excessive system pressure and provide overload protection. A cooler is connected in series in the system's return oil circuit to cool the hydraulic oil and ensure that the hydraulic oil temperature is controlled at 60-80℃. A pressure sensor is installed at the oil outlet of the closed-loop pump, and a speed sensor is installed on the output shaft of the travel motor. Both are electrically connected to the PLC controller to provide real-time feedback of system pressure and travel speed signals. The PLC controller is electrically connected to the operating handle and the electro-proportional control valve to receive signals and output commands.

[0256] 3. Work process:

[0257] (1) Start-up phase: Start the lawnmower engine. The engine drives the electronically controlled closed pump to run. At this time, the operating handle is in the neutral position, the displacement of the electronically controlled closed pump is 0, the hydraulic system has no pressure output, the travel motor does not run, and the equipment is in a stationary state.

[0258] (2) Forward and backward control: When the operating handle is moved forward (forward gear) or backward (reverse gear), the PLC controller receives the handle signal, controls the electro-proportional control valve to act, adjusts the displacement of the electro-controlled closed pump, and the hydraulic oil is input to the travel motor through the high-pressure oil pipe, driving the travel motor to rotate in the forward or reverse direction. The travel motor drives the drive wheel to rotate, which in turn drives the track to move, realizing the forward or backward movement of the equipment; the displacement of the electro-controlled closed pump is adjusted by the stroke of the operating handle, thereby adjusting the travel speed, with a speed range of 0.5-5km / h.

[0259] (3) Steering control: When steering is required, the displacement of the single-side travel motor is controlled by operating the handle (e.g., the displacement of the left motor decreases while the displacement of the right motor remains unchanged to achieve left steering; conversely, right steering is achieved by increasing the displacement of the left motor and decreasing the displacement of the right motor), or the single-side motor is controlled to rotate in the opposite direction to achieve on-the-spot steering. The steering process is smooth and without obvious jerking.

[0260] (4) Overload protection: When the load is too large during operation and the hydraulic system pressure exceeds the rated pressure of the relief valve (20MPa), the relief valve will open automatically to return the excess hydraulic oil to the oil tank, so as to avoid damage to components such as closed pump and travel motor due to excessive pressure.

[0261] (5) Heat dissipation control: The hydraulic oil is cooled by the cooler during the circulation process. When the oil temperature exceeds 55°C, the PLC controller controls the cooler to accelerate the operation to ensure that the oil temperature is maintained within the normal working range and to avoid the system performance being affected by excessive oil temperature.

[0262] Example 3:

[0263] Please see Figures 1 to 5 This embodiment provides an enhanced electronically controlled closed-loop pump hydraulic drive walking system;

[0264] This embodiment is an optimization based on Embodiment 2, and is suitable for heavy-duty mowing operations with high loads and extremely complex terrain (steep slopes, gravel areas). Specific improvements and implementation details are as follows:

[0265] 1. Optimization and selection of core components:

[0266] (1) Closed-loop pump: Two large-displacement plunger-type closed-loop pumps are selected, with a displacement of 15ml / r, a rated working pressure of 25MPa, a rated speed of 3600r / min, and equipped with an electro-proportional control valve. The displacement is precisely adjusted through the electronic control system, and the response time is ≤0.1s.

[0267] (2) Walking motor: a high-speed piston hydraulic motor is selected, with a rated working pressure of 40MPa, a rated speed of 1800r / min, and an output torque of 550N·m. It has overload protection function and stronger impact resistance.

[0268] (3) Electro-proportional valve: A four-way electro-proportional valve assembly is selected, with a maximum working pressure of 40 bar, which is suitable for closed pumps.

[0269] (4) Electrical control system: a remote control system with PLC controller and integrated display screen, which can display parameters such as hydraulic system pressure, oil temperature and walking speed in real time, supports parameter setting and fault alarm, and the control distance is ≤150m;

[0270] (5) Auxiliary components: hydraulic oil tank (capacity 20L), suction filter element (filtration accuracy 100μm), suction and return oil integrated filter (suction filtration accuracy 80μm, return oil filtration accuracy 10μm), cooler (air-cooled, heat dissipation power 4kW), hydraulic pipeline, accumulator.

[0271] 2. System Improvement and Layout:

[0272] Based on the system in Example 2, an accumulator is added in parallel to the oil outlet of the electrically controlled closed pump to buffer hydraulic pressure fluctuations during sudden load changes and avoid system shocks; a pressure buffer valve is added to the hydraulic circuit to further optimize the smoothness of power transmission; the wireless remote control module is electrically connected to the PLC controller and a travel compensation potentiometer is added to realize remote control of equipment start-up, stop, speed adjustment, steering, offset compensation, etc., which is more suitable for dangerous operation scenarios (such as operation on the edge of a steep slope).

[0273] 3. Work process:

[0274] After starting the engine, the closed-loop pump operates. The walking speed and working mode (high-speed mode, high-load mode) can be set via wireless remote control. In high-load mode, the PLC controller automatically adjusts the displacement of the closed-loop pump, increases the hydraulic system pressure, and ensures that the walking motor outputs sufficient torque to cope with complex working conditions such as gravel ground and steep slopes. When the load changes suddenly, the accumulator buffers the pressure fluctuation, and the two-way relief valve provides two-way overload protection to avoid component damage. The equipment can be remotely controlled to steer and adjust the speed via wireless remote control, eliminating the need for close-range operation by personnel and improving operational safety.

[0275] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A tracked heavy-duty lawnmower, characterized in that, include: The machine body (1) has two sets of track wheel sets (2) on its side, and the track wheel sets (2) include tracks (3) and drive wheel sets (4). A mowing assembly (5) is disposed at the bottom of the body (1); A drive control component (6) is mounted on the machine body (1) and is used to control the movement and operation of the lawnmower. The drive control component (6) is equipped with a hydraulic drive walking system; The hydraulically driven walking system includes: Power source, closed-loop pump, travel motor, electro-proportional valve, electronic control system, and auxiliary hydraulic components; The electrical control system includes a PLC controller, an operation component, a pressure sensor, a speed sensor, a circuit component, and a data calculation and analysis component. The data calculation and analysis component has a built-in adjustment and control system. By collecting data on the operation of the lawnmower and processing the data through the data calculation and analysis component, it outputs the total walking resistance, the target displacement of the closed pump, and the lateral stability coefficient. The data calculation and analysis component is used to analyze the walking stability of the lawnmower in real time and dynamically adjust the discharge rate of the closed pump. The integrated calculation module built into the data calculation and analysis component includes a walking resistance unit, a closed-loop pump discharge unit, and a walking stability integrated unit. The total walking resistance output by the walking resistance unit is input into the closed-loop pump discharge unit. The target displacement of the closed-loop pump discharge unit and the parameters involved in the walking resistance unit are input into the walking stability integrated unit to output the lateral stability coefficient and the corrected target displacement. That is, the walking resistance unit, the closed-loop pump discharge unit, and the walking stability integrated unit have a three-level progressive logical calculation relationship. The auxiliary hydraulic components include a hydraulic tank, a hydraulic filter, a relief valve, a cooler, an accumulator, and hydraulic hoses.

2. The tracked heavy-duty lawnmower according to claim 1, characterized in that: The power source is a gasoline engine, which is used to drive the closed pump to provide power to the hydraulic system; The closed-loop pump is a variable displacement piston closed-loop pump, which enables power output on demand; The travel motor is a cycloidal hydraulic motor, which enables the equipment to move forward and backward. The output shaft of the gasoline engine is fixedly connected to the power input end of the closed pump via a coupling. When the gasoline engine is running, it drives the closed pump to run synchronously, providing power to the hydraulic drive walking system. The oil outlet of the closed pump is connected to the inlet and outlet of the travel motor through a high-pressure hydraulic oil pipe to form a closed hydraulic transmission circuit. The overflow valve is integrated into the closed pump, the cooler is connected in series in the return oil circuit, the accumulator is connected in parallel at the oil outlet of the closed pump, and the hydraulic filter element is installed at the oil inlet of the closed pump and the oil return port of the main oil circuit. The PLC controller is electrically connected to the operating component, the electro-proportional control valve, the pressure sensor, and the speed sensor. The pressure sensor is installed at the oil outlet of the closed pump to collect the hydraulic system pressure signal. The speed sensor is installed on the output shaft of the travel motor to collect the travel speed signal. After receiving the above signals, the PLC controller controls the electro-proportional control valve to adjust the displacement of the closed pump according to the instructions of the operating component, thereby controlling the travel motor. The wireless remote control module is connected to the PLC controller.

3. The tracked heavy-duty lawnmower according to claim 1, characterized in that: The data calculation and analysis component includes: The multi-source sensor data acquisition module collects and analyzes data from the lawnmower during operation to obtain data on walking resistance, closed-loop pump discharge, and walking stability. The transfer processing module receives walking resistance data, closed-loop pump discharge data, and walking stability data, cleans the acquired data, and stores it in the database. The integrated calculation module retrieves the walking resistance data, closed-loop pump discharge data, and walking stability data processed by the transfer processing module from the database; Comprehensive Calculation Module: The total walking resistance is output based on the ground rolling resistance coefficient, total machine mass, gravitational acceleration, ground slope angle, and additional resistance from mowing operations in the walking resistance data. Based on the drive wheel pitch circle radius, travel motor mechanical efficiency, travel motor volumetric efficiency, hydraulic system working pressure difference, transmission ratio between drive wheel and motor, and hydraulic oil temperature-viscosity coefficient in the closed-loop pump discharge data, and combined with the total travel resistance, the target displacement of the closed-loop pump is output. Based on the overall machine center of gravity height, turning radius, track center distance and track ground pressure dynamic distribution coefficient in the walking stability data, and combined with the total walking resistance, the lateral stability coefficient is finally output. The lateral stability coefficient is combined with the closed pump target displacement to calculate the corrected target displacement. The execution management module receives the total travel resistance, the target displacement of the closed-loop pump, and the corrected target displacement. The execution management module manages the electro-proportional valve and executes the hydraulic power.

4. The tracked heavy-duty lawnmower according to claim 3, characterized in that: The execution management module includes an electro-proportional valve drive unit and a hydraulic power execution unit.

5. The tracked heavy-duty lawnmower according to claim 4, characterized in that: The processing flow of the walking resistance unit is as follows: A1. Assign values ​​based on the type of ground in the agricultural use scenario of the lawnmower to analyze the ground rolling resistance coefficient; A2. Combine the analysis of the machine mass, gravitational acceleration, and ground slope angle, and introduce the ground slope angle in the form of sine and cosine functions to decompose the gravity in two directions: perpendicular to the ground and parallel to the ground, thereby analyzing the components perpendicular to the ground and parallel to the ground. A3. By analyzing the additional walking resistance generated by the interaction between the cutting blades and vegetation during lawn mowing, we can analyze the changes in walking speed caused by load changes, introduce additional resistance during lawn mowing, and finally output the total walking resistance.

6. The tracked heavy-duty lawnmower according to claim 5, characterized in that: The processing flow of the closed-loop pump discharge unit is as follows: B1. By introducing the pitch circle radius of the drive wheel and combining it with the total travel resistance, we can analyze the required driving torque on the drive wheel. B2. By analyzing the ratio of output power to input hydraulic power after mechanical friction loss in the travel motor, the degree of energy loss due to internal friction of the motor can be reflected, so as to introduce the mechanical efficiency of the travel motor. B3. By analyzing the ratio of the actual output flow rate to the theoretical input flow rate of the travel motor, the degree of internal leakage loss of the motor can be reflected, so as to introduce the volumetric efficiency of the travel motor. B4. By analyzing the pressure difference between the oil outlet and return port of the closed pump, the relationship between the working pressure difference and the actual load of the hydraulic system is quantified, so as to introduce the working pressure difference of the hydraulic system. B5. By analyzing the transmission ratio of the reduction mechanism between the output shaft of the travel motor and the drive wheel, the amplification factor of the output torque of the travel motor when it is transmitted to the drive wheel is quantified, so as to introduce the transmission ratio between the drive wheel and the motor. B6. By analyzing the dynamic synergistic relationship between the current temperature and viscosity of hydraulic oil, the temperature-viscosity synergistic weighting coefficient, real-time oil temperature, optimal operating temperature of hydraulic oil, and kinematic viscosity at the current temperature are combined and calculated to output the hydraulic oil temperature-viscosity synergistic coefficient.

7. The tracked heavy-duty lawnmower according to claim 6, characterized in that: The processing flow of the walking stability integrated unit is as follows: C1. By analyzing the vertical height of the lawnmower's center of gravity relative to the ground, the relationship between the center of gravity height and the risk of tipping over is quantified, thus introducing the overall center of gravity height. C2. Analyze the turning radius of the lawnmower when it turns. It is obtained by combining the rotation speeds of the left and right motors. The turning radius is the key to the source of centrifugal force in the stability determination. C3. By analyzing the horizontal distance between the longitudinal centerlines of the left and right tracks, the relationship between track center distance and stability is analyzed, thus introducing track center distance. C4. By analyzing the synergistic relationship between the non-uniformity of the track ground pressure distribution and the proportion of the actual bearing area, and combining the maximum specific pressure of the track ground pressure, the average specific pressure of the track ground pressure, the actual bearing area, and the total area of ​​the track ground pressure, a dynamic distribution coefficient of track ground pressure is introduced to finally output the lateral stability coefficient. The lateral stability coefficient is then combined with the compensation strength coefficient and the target displacement of the closed pump to output the corrected target displacement.

8. The tracked heavy-duty lawnmower according to claim 3, characterized in that: The processing flow of the electro-proportional valve drive unit is as follows: The PLC controller converts the corrected target displacement into a target control current based on the calibration curve of the electro-proportional control valve of the closed pump. The PWM output module of the PLC controller generates a PWM signal with a corresponding duty cycle based on the target control current. After being amplified by the proportional amplifier, the signal drives the electromagnet of the electro-proportional valve. The valve core of the electro-proportional valve is displaced according to the magnitude of the electromagnetic force, which adjusts the swashplate angle of the closed pump so that the actual displacement of the closed pump approaches the corrected target displacement. The processing flow of the hydraulic power actuator is as follows: Power conversion: The engine drives the closed pump to operate through the coupling. Under the adjustment of the electro-proportional valve, the closed pump outputs hydraulic oil flow corresponding to the corrected target displacement. The high-pressure hydraulic oil is delivered to the travel motor through the high-pressure oil pipe. Power execution: High-pressure hydraulic oil enters the travel motor, driving the motor rotor to rotate, converting hydraulic power into mechanical power. The output shaft of the travel motor drives the drive wheel to rotate, and the drive wheel meshes with the track, causing the track to generate friction with the ground, thus realizing the lawnmower's forward, backward, and turning movements.

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