Calibration matching test method for dual-mode off-road vehicle under desert working condition

Abstract

The invention discloses a calibration matching test method for a dual-mode off-road vehicle under a desert working condition, and belongs to the field of vehicle engineering, and the method comprises the steps: selecting a test site according with the desert working condition, and deploying equipment needed by calibration test; preparing a calibrated vehicle, sending the calibrated vehicle to a test site after spot inspection by an engineer, and synchronizing spot inspection records; torque chain calibration, inter-shaft torque distribution calibration, ESP calibration, torque transfer calibration, power guarantee performance calibration, feedback performance calibration and thermal management performance calibration are carried out in sequence. According to the method, a power system simulation model is established based on desert terrain data acquired by a real vehicle, a parameter optimization direction is predicted in advance, and dependence on field testing is reduced; and then the optimization effect is verified through real vehicle testing, development stage testing can be carried out without limitation of regions and environments, product risk points can be recognized in advance, the traditional desert environment calibration period can be shortened, personnel and vehicle safety risks and test expenditures can be reduced, and the industrial pain point that desert working condition calibration can only be completed on site is solved.

Description

Technical Field

[0001] This application belongs to the field of vehicle engineering, and specifically relates to a calibration and matching test method for a dual-mode off-road vehicle under desert conditions. Background Technology

[0002] With the development of new energy vehicle technology, dual-mode off-road vehicles have become an important development direction for off-road vehicles due to their balance of power performance and energy efficiency. Desert conditions, as a typical extreme off-road scenario, are characterized by soft terrain, large gradients, high temperatures, and complex heat dissipation conditions. This places stringent demands on the power output, four-wheel drive response, thermal management, and battery retention capabilities of dual-mode off-road vehicles. Targeted calibration and matching are necessary to ensure reliable passability, economy, and safety in desert environments. Currently, industry research on vehicle calibration mainly focuses on ordinary scenarios such as urban roads and conventional highways; a mature calibration system for extreme environments such as deserts has not yet been established.

[0003] The existing calibration and matching tests for dual-mode off-road vehicles in desert conditions have long relied on a single mode of on-site testing, which has the following problems: It relies heavily on on-site testing and is subject to significant geographical and environmental limitations. The terrain features and climate conditions of desert environments are difficult to reproduce on test benches, necessitating calibration tests to be conducted in real desert sites. Due to the limitations of site location and seasonal climate, testing during the development phase is difficult to advance flexibly, thus extending the project cycle. On-site testing requires a large investment of manpower and resources, and the desert environment presents safety hazards such as sand trapping and vehicle malfunctions, which not only increases the safety risks to personnel and vehicles, but also leads to a significant increase in test costs, which is not conducive to technology iteration and optimization. Traditional field testing requires the vehicle to enter the desert site before parameter verification can be carried out. It is impossible to predict the compatibility issues of the power system parameters in advance. If unreasonable parameters are found, it is necessary to go back and forth to adjust and test on the field again, which further prolongs the development cycle and is prone to overlooking potential risks. Summary of the Invention

[0004] To address the aforementioned issues, this application provides a calibration and matching test method for dual-mode off-road vehicles under desert conditions. This method can shorten the calibration cycle in traditional desert environments, reduce personnel and vehicle safety risks and testing costs, and solve the industry pain point that desert condition calibration can only be completed on-site.

[0005] A calibration and matching test method for a dual-mode off-road vehicle under desert conditions, targeting off-road vehicles with both pure electric and hybrid dual-mode drive, including: Select a test site suitable for desert conditions and deploy the equipment required for calibration testing; The calibration vehicle is prepared, inspected by the engineer, and then sent to the test site with the inspection record kept simultaneously. Torque chain calibration, inter-axle torque distribution calibration, ESP calibration, torque transfer calibration, power preservation performance calibration, feedback performance calibration, and thermal management performance calibration were carried out in sequence. Simultaneously, a hybrid verification method combining virtual calibration and real vehicle testing was adopted to collect data from each calibration stage and optimize the parameters of each calibration stage to adapt the pure electric and hybrid dual-mode power system to desert conditions. The parameters for each calibration stage include: torque output data, wheel slippage data, braking performance data, torque transfer response data, battery charging and discharging power data, motor feedback power data, and temperature data of each system; the parameters for each calibration stage also include: inter-axle torque distribution ratio, ESP control parameters, torque transfer threshold, power preservation strategy parameters, feedback intensity parameters, and thermal management control parameters.

[0006] Optionally, preparations are made for the calibration vehicle, including: Ensure that all vehicle assemblies, systems, components, accessories, and auxiliary devices, along with onboard tools and a spare tire, are complete; When the engine is cold, adjust the tire pressure to the value designed for the terrain mode. Select fuels, lubricants, brake fluids, antifreeze, and power steering fluids that meet the vehicle's technical requirements; Ensure that the key hardware of the steering, transmission, braking, cooling, thermal management, and suspension systems, as well as the key software of VCU, ECU, BMS, IPB, CCU, MCU, and domain controllers, meet the required standards. Ensure that the break-in mileage of the test vehicle is not less than the preset value, install a high-strength roll cage and carry off-road equipment.

[0007] Optionally, the test site may have typical desert terrain and high-temperature climate characteristics; The equipment required for deployment and calibration testing includes: The test system was built using equipment such as ETAS582.1 calibrated data acquisition, VECTOR1630A online data acquisition, VBOX, and gyroscope; The testing equipment also includes a Hilta offline data acquisition system, a multi-functional environmental tester, an inclinometer, a laser rangefinder, and a GoPro action camera. The GoPro action camera is used to record the vehicle's driving posture, and the laser rangefinder is used to measure the slope of the ramp. Together, they complete the full-dimensional acquisition of working condition data and support the hybrid verification of virtual calibration and real vehicle testing. Optionally, torque chain calibration includes: Measure the vehicle's curb weight, light load weight, half load weight and full load weight, and record the axle load distribution data simultaneously. Determine the benchmark ratio of axle torque distribution under horizontal sand conditions based on the axle load distribution data. Confirm the ESP software status and completely turn it off via a switch to eliminate interference from the ESP system on the torque output of the powertrain. For the vehicle's 4H and 4L four-wheel drive modes, torque loading parameters are set separately so that the torque loading slope and step size of the 4L mode are greater than those of the 4H mode. The torque output characteristics were tested at ten throttle openings: 10%, 20%...100%. Each opening point was tested three times, and subjective evaluations were conducted simultaneously to determine whether the torque output met the driver's power expectations for desert conditions. Optionally, the inter-shaft torque distribution calibration includes: Under flat sandy conditions, the test loads were set at the standard load, light load, half load and full load respectively. The acceleration process was tested under different throttle openings by switching between D and R gears, and the wheel slippage synchronization between the axles was observed. If the wheels on the axle slip out of sync, adjust the torque distribution ratio between the axles until the wheels on the axles slip out in the same way. Under desert slope conditions with different gradients, the above load and gear test process was repeated to capture the critical state of wheel slippage between the axles during the climbing process. Based on the slippage synchronization, the torque distribution ratio was adjusted to ensure that the power distribution between the axles under the slope conditions is adapted to the sand adhesion characteristics. Optionally, ESP calibration includes: Under desert conditions such as flat sandy land, sandy slopes, herder trails, traversing the desert, brushing the pot, and riding the knife edge, the test loads are set at the calibrated load, light load, half load, and full load to calibrate the braking performance, braking stability, and pedal feel, ensuring that the braking performance meets the vehicle design specifications. Simultaneously calibrate TCS performance parameters and test the vehicle stability during start-up acceleration, hill climbing, and getting out of trouble, so that the TCS function can be adapted to the soft desert road surface. For different ESP switch positions, the corresponding TCS and VDC performance parameters are calibrated to cover the needs of different desert driving scenarios. The gear positions include ON, shallow OFF, deep OFF, and completely OFF; Optionally, torque transfer calibration includes: Based on the completion of torque chain calibration and ESP calibration, for the inter-wheel torque transfer, the coaxial single wheel slippage condition is simulated, and the torque distribution ratio of the non-slipping wheel is adjusted to achieve torque transfer to the non-slipping wheel; To address inter-axle torque transfer, a scenario of simultaneous slippage of two wheels on a single axle is simulated, and the torque distribution ratio of the other axle is adjusted to achieve cross-axle torque transfer. The test conditions cover sandy cross-axle escape, slope escape, blade edge escape, shoal, pot-scraping and herder trail crossing. The test loads include the calibration load, half load and full load to ensure that the torque transfer response speed and distribution accuracy meet the design subjective and objective indicators. Optionally, the power retention performance calibration includes: Using full load as the test load, under typical desert conditions such as crossing the herdsman's road, shoveling, shoveling pots, and riding the knife edge, message data was collected through the ETAS582.1 calibration data acquisition system, and temperature data of key components were collected using a point thermometer. Statistical analysis of motor discharge power curves and throttle opening variation curves under different operating conditions; Based on data on battery pack charging and discharging power, generator power, engine power, compressor power, and engine and generator efficiency, a power retention performance optimization model is established, and relevant parameters are adjusted to ensure that the vehicle's power retention capability under desert conditions meets design requirements, while also taking into account power, energy consumption, and NVH performance. Optionally, the feedback performance calibration includes: Distinguish between coasting feedback and braking feedback, define coasting feedback levels according to the project's preset strategy, and test the motor feedback intensity of different levels under conditions such as crossing herdsmen's trails, rushing uphill, brushing pots, riding on knife edges, and descending sandy slopes. The VECTOR1630A is used to collect motor feedback power data online. When the coasting feedback power exceeds the motor's load capacity, the electro-hydraulic braking system is triggered to actively intervene and ensure the stability of feedback performance. For vehicles equipped with 4H and 4L modes, the feedback parameters in the two modes were calibrated to adapt the feedback performance to different desert four-wheel drive scenarios. The test process used full load as a fixed load. Optionally, the following preparatory work needs to be done before carrying out thermal management performance calibration: Temperature sensors were placed on the head of the vehicle occupants, the air conditioning vents, the surface of the battery pack, key components of the three-electric system, and the pipelines of the high and low temperature heat dissipation system to verify the accuracy of sensor data acquisition. Check the cooling pipes for leaks; Add refrigerant to the air conditioning system according to the design standards, and confirm that the components of the battery pack thermal management system, high-temperature heat dissipation system, and low-temperature heat dissipation system are functioning normally, and that the software control logic is in a state of pending calibration.

[0008] Optionally, thermal management performance calibration includes: In a high-temperature desert environment with an ambient temperature of no less than 38℃, the vehicle was fully loaded and operated by a driver with more than 5 years of desert off-road experience, simulating the driving style of a professional guide, to test conditions such as idling to generate electricity, idling to cool down, crossing herdsmen's trails, climbing hills, washing pots, and riding on knife-edge terrain. Temperature sensors are used to collect coolant temperature, air conditioning vent temperature, passenger head temperature, and the temperature of the three-electric system, and the cooling rate of each temperature parameter is statistically analyzed. If an over-temperature alarm or over-temperature power limitation occurs, adjust the thermal management system control parameters until the vehicle's thermal balance performance under high-temperature desert conditions meets the design specifications.

[0009] Compared with the prior art, this application has the following advantages: 1. Breaking the limitations of on-site testing in desert conditions, a hybrid verification system combining virtual calibration and real vehicle testing is constructed: This system first builds a powertrain simulation model based on desert terrain data collected from real vehicles, predicting parameter optimization directions in advance and reducing reliance on on-site testing; then, real vehicle testing verifies the optimization effect. This eliminates the need for development-stage testing due to geographical or environmental limitations, enabling early identification of product risks, shortening the traditional desert environment calibration cycle, reducing personnel and vehicle safety risks and testing costs, and solving the industry pain point that desert condition calibration can only be completed on-site. 2. Innovative multi-dimensional collaborative calibration strategy to comprehensively improve the desert adaptability of dual-mode power system: Through torque chain calibration, the torque loading characteristics of specific four-wheel drive modes are adapted to extreme terrains such as steep slopes and knife-edges, accelerating torque response speed; combined with inter-axle torque distribution calibration and torque transfer calibration, the wheel slippage between axles is synchronized, shortening the torque transfer response time and improving the passability on soft sand dune terrain; in conjunction with the power retention performance calibration, a stable power level is maintained under desert conditions, reducing the range reduction in pure electric mode and lowering fuel consumption in hybrid mode. Multi-dimensional parameter collaborative optimization breaks through the performance limitations of traditional single calibration.

[0010] Other features and advantages of this application will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the application. The objectives and other advantages of this application may be realized and obtained by means of the structures pointed out in the description, claims and drawings. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 A workflow diagram is shown. Detailed Implementation

[0013] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0014] It should be noted that a dual-mode off-road vehicle is an off-road vehicle that simultaneously possesses both pure electric (EV) and hybrid electric (HEV) driving modes. It can flexibly switch driving modes according to different driving conditions to balance power output and energy efficiency. Desert conditions, as a typical extreme driving environment, are characterized by soft terrain, large gradient changes, high temperatures, and complex heat dissipation conditions, which place stringent requirements on the vehicle's power system's torque control, mode switching, thermal management, and battery retention capabilities.

[0015] This application addresses the desert condition adaptation requirements of dual-mode off-road vehicles by optimizing key parameters of the power system through a systematic calibration and matching test method, ensuring that the vehicle has reliable passability, economy, and safety in desert environments.

[0016] The specific implementation methods of this application are illustrated below through examples: See attached document Figure 1 A calibration and matching test method for a dual-mode off-road vehicle under desert conditions, targeting off-road vehicles with both pure electric and hybrid dual-mode drive, the method includes: S1: Select a test site that meets desert working conditions and deploy the equipment required for calibration testing.

[0017] Specifically, the test site must cover typical desert terrain to simulate real off-road scenarios. Priority should be given to any one of the Tengger Desert, Badain Jaran Desert, or Ulan Buh Desert in Alxa League, Inner Mongolia. These sites have diverse terrains such as flat sandy areas, desert slopes with varying gradients, long desert slopes, desert ridges, pot-shaped sand dunes, and herder trails. They also maintain a high-temperature climate year-round, meeting the environmental requirements for desert operation testing. If the above-mentioned site conditions are limited, other sites with typical desert terrain and high-temperature climate characteristics can also be selected to ensure that the test environment is consistent with the real desert usage scenario.

[0018] When deploying the equipment required for calibration testing, a complete testing system covering data acquisition, environmental monitoring, and attitude recording needs to be built. The core equipment includes the ETAS582.1 calibration data acquisition system, the VECTOR1630A online data acquisition system, the VBOX, and a gyroscope. The ETAS582.1 calibration data acquisition system is used to collect real-time message data of the vehicle's power system. The VECTOR1630A online data acquisition system is responsible for synchronously recording key parameters such as motor torque and engine power. The VBOX and gyroscope work together to acquire vehicle speed, acceleration, and vehicle attitude data. Auxiliary equipment includes the Hilta offline data acquisition system, a multi-functional environmental tester, an inclinometer, a laser rangefinder, and a GoPro action camera. The Hilta offline data acquisition system is used to back up key test data to prevent loss. The multi-functional environmental tester monitors the ambient temperature, humidity, and dust concentration in real time. The inclinometer accurately measures the slope value of the desert slope. The laser rangefinder is used to record the slope height and blade width. The GoPro action camera is fixed around the vehicle body via a vehicle-mounted bracket to record the vehicle's driving attitude and sand terrain features. All devices work together to collect operating condition data from all dimensions, providing data support for the hybrid verification of virtual calibration and real vehicle testing.

[0019] S2: Prepare the calibration vehicle, and after inspection by the engineer, send it to the test site and record the inspection results simultaneously.

[0020] Specifically, vehicle calibration preparation needs to cover dimensions such as hardware equipment, fluid filling, software and hardware status verification, and safety configuration to ensure that the vehicle meets the requirements for desert working condition testing.

[0021] First, it is necessary to ensure that all assemblies, systems, components, accessories and auxiliary devices of the vehicle, as well as the vehicle tools and spare tire equipment, are complete, without missing or damaged parts, so as to avoid affecting the test results due to missing parts; Secondly, when the vehicle is cold, adjust the tire pressure to the design value for the terrain mode. The cold state is defined as the vehicle being left in the ambient temperature for at least 4 hours. The tire pressure setting needs to be adapted to the low adhesion characteristics of sandy terrain, usually 20-30 kPa lower than the tire pressure of regular roads, in order to increase the tire contact area and reduce the risk of getting stuck in sand. Secondly, select fuel, lubricating oil, brake fluid, antifreeze, and power steering fluid that meet the vehicle's technical requirements. The fuel grade must match the engine's compression ratio, the lubricating oil must meet the lubrication requirements in a high-temperature desert environment, and the antifreeze's freezing point must be at least 10°C lower than the lowest temperature at the test site to ensure that all systems function properly. Next, check the critical hardware status of the steering system, transmission system, braking system, cooling system, thermal management system and suspension system to ensure there is no wear, looseness or leakage. At the same time, upgrade the key software of VCU, ECU, BMS, IPB, CCU, MCU and domain controller to the optimal version or test the specified version, and read the software version number with a diagnostic tool to confirm that there are no fault codes. Finally, ensure that the test vehicle has a break-in mileage of no less than 1,000 km. During the break-in mileage, avoid rapid acceleration, rapid deceleration and overloading. After the break-in is completed, install a high-strength roll cage. The roll cage material must be high-strength steel, and the strength of the welding points must meet the off-road safety standards. Also, carry necessary off-road equipment, including anti-skid plates, tow ropes, emergency fuel tanks and sand traps.

[0022] Once the vehicle is ready, it must be jointly inspected by calibration and test engineers. The calibration engineer focuses on checking the powertrain hardware and software status, using a diagnostic tool to read the parameter configurations of controllers such as the VCU and ECU to confirm there are no abnormalities. The test engineer focuses on checking the installation of test equipment, confirming that sensors are securely connected and data acquisition is normal. During the inspection, a hardware and software inspection record must be filled out, including the component name, model, status, software version number, and equipment installation location. After the inspection is passed, the record is signed and confirmed, and the vehicle is sent to the test site. The inspection record is also synchronized to the test site to facilitate tracing the vehicle's initial state during testing.

[0023] S3: Conduct torque chain calibration, inter-axle torque distribution calibration, ESP calibration, torque transfer calibration, power preservation performance calibration, feedback performance calibration, and thermal management performance calibration in sequence. Simultaneously adopt a hybrid verification method that combines virtual calibration and real vehicle testing, collect data from each calibration stage, and optimize the parameters of each calibration stage to adapt the pure electric and hybrid dual-mode power system to desert conditions.

[0024] The specific implementation methods for each calibration step are explained below: S301, Torque Chain Calibration: Specifically, torque chain calibration aims to optimize the torque output characteristics of the powertrain under desert conditions, ensuring that the power response meets the driver's expectations.

[0025] First, the vehicle's curb weight, light load weight, half load weight, and full load weight are measured. Light load weight is defined as the curb weight plus the weight of one driver; half load weight is defined as the curb weight plus the weight of two drivers and 50% of the rated load; and full load weight is defined as the curb weight plus the rated load. The vehicle's weight and axle load distribution data for each load are measured using a weighbridge. Based on the axle load distribution data, the benchmark ratio of torque distribution between axles under level sand conditions is determined. Generally, axles with higher axle load ratios are assigned a higher torque ratio to improve power utilization efficiency. Secondly, confirm the ESP software status and completely turn it off using a switch. Read the ESP system status code using a diagnostic tool to ensure that the ESP system has no activation signal, eliminate the interference of the ESP system on the torque output of the power system, and avoid torque limitation caused by ESP intervention. Then, torque loading parameters were set for the vehicle's 4H and 4L four-wheel drive modes respectively. The 4H mode is suitable for regular desert terrain, with the torque loading slope set to 50-80 N·m / s and the step size set to 10-15 N·m. The 4L mode is suitable for extreme terrains such as steep slopes and knife-edges, with the torque loading slope set to 80-120 N·m / s and the step size set to 15-20 N·m. The torque loading slope and step size of the 4L mode are made to be greater than those of the 4H mode to provide stronger power response. Finally, the torque output characteristics were tested at ten throttle openings, from 10% to 100%. Each opening point was tested three times, and the average torque of the three tests was taken as the benchmark torque at that opening. Simultaneously, three drivers with desert off-road experience conducted subjective evaluations, including torque response speed, power output smoothness, and starting and getting out of trouble, to determine whether the torque output met the drivers' power expectations for desert conditions. If the subjective evaluation was not satisfactory, the torque loading parameters were adjusted, and the test was repeated until the expectations were met.

[0026] S302, Inter-shaft torque distribution calibration: Specifically, the inter-axle torque distribution calibration is designed to ensure that the front and rear axle wheels slip synchronously under desert conditions, thereby improving vehicle passability.

[0027] First, under flat sandy conditions, the test loads were set at the calibrated load, light load, half load, and full load. The calibrated load was defined as the test load for the whole vehicle design. The D and R gears were switched. The D gear was used for forward driving test, and the R gear was used for reverse traction test. The acceleration process under different throttle openings was tested. The front and rear axle wheel speed data were collected through VBOX, the front and rear axle wheel slip ratio was calculated, and the synchronicity of wheel slip between the axles was observed. The slip ratio difference was less than 5% and was considered to be synchronized. If the wheels on the axles slip asynchronously, adjust the torque distribution ratio between the axles based on the difference in slip rate. For axles with a high slip rate, appropriately reduce the torque distribution ratio, and for axles with a low slip rate, appropriately increase the torque distribution ratio. Each adjustment should be made by 5% to 10% until the wheels on the axles slip in the same way. Then, under different slope conditions on desert slopes, the slope was measured with a slope meter. Three typical slopes of 15°, 25°, and 35° were selected, and the above load and gear test process was repeated to capture the critical state of wheel slippage between axles during the climbing process. The critical state was defined as the initial throttle opening at which the wheel begins to slip continuously. Based on the critical slippage state, the torque distribution ratio was adjusted to ensure that the power distribution between axles under slope conditions was adapted to the adhesion characteristics of the sand and to avoid excessive slippage of a single axle leading to sand trapping.

[0028] S303, ESP calibration: Specifically, ESP calibration aims to optimize vehicle braking performance and driving stability in desert conditions.

[0029] First, under desert conditions such as flat sandy ground, sandy slopes, herder trails, traversing sand dunes, and riding on sharp cliffs, the test loads were set at calibrated load, light load, half load, and full load to calibrate braking performance, braking stability, and pedal feel. Braking performance was measured by VBOX to determine the braking distance from 100km / h to 0. Braking stability was measured by gyroscope to determine the vehicle body roll angle during braking. Pedal feel was measured by pressure sensor to determine the relationship between brake pedal force and travel, ensuring that the braking distance, vehicle body roll angle, and pedal force-travel curves meet the vehicle design specifications. Secondly, the TCS performance parameters were calibrated simultaneously, and the overall vehicle stability was tested during start-up acceleration, hill climbing, and getting out of trouble. The torque of the drive wheel was collected by the torque sensor, and the TCS intervention threshold was adjusted so that the TCS would intervene when the wheel slip rate reached 15% to 20%, limiting the drive wheel torque and avoiding excessive slippage, thus adapting to the soft desert road surface. Finally, for different ESP switch positions, the corresponding TCS and VDC performance parameters were calibrated. The positions include ON, shallow off, deep off, and completely off. The ON position is suitable for normal desert driving, with TCS and VDC intervening normally. The shallow off position is suitable for mild traction problems, with the TCS intervention threshold increased by 20%. The deep off position is suitable for moderate traction problems, with TCS off and VDC retaining basic functions. The completely off position is suitable for extreme traction problems, with TCS and VDC completely off, covering the needs of different desert driving scenarios.

[0030] S304, Torque Transfer Calibration: Specifically, the torque transfer calibration aims to achieve intelligent torque transfer between wheels and axles under desert conditions, thereby improving the ability to get out of trouble.

[0031] First, based on the completion of torque chain calibration and ESP calibration, regarding the torque transfer between wheels, a sand cross-axle test bench was used to simulate the slippage condition of a single wheel on the same axle. The slippage rate of a single wheel was set to 50% to 60%. The slippage data was collected by wheel speed sensors, and the torque distribution ratio of the non-slipping wheel was adjusted to increase the torque of the non-slipping wheel by 20% to 40%, thereby realizing the transfer of torque to the non-slipping wheel and ensuring the effective utilization of the power of the coaxial wheel. Secondly, regarding the inter-axle torque transfer, a dual-axle slip test bench was used to simulate the simultaneous slippage of two wheels on a single axle. The slippage rate of a single axle was set to 40% to 50%. Based on the axle speed difference, the torque distribution ratio of the other axle was adjusted to increase the torque ratio of the non-slipping axle to 60% to 80%, thereby achieving cross-axle torque transfer and avoiding vehicle stalling caused by single-axle slippage. Then, the test conditions covered sandy cross-axle escape, slope escape, blade edge escape, ramp escape, pothole escape, and herder trail crossing. Each condition was tested 5 times. The test loads included the calibrated load, half load, and full load. The torque transfer response time was collected by a torque tester to ensure that the response time was less than 0.5s. The driver's subjective evaluation was used to judge the escape effect to ensure that the torque transfer response speed and distribution accuracy met the design subjective and objective indicators.

[0032] S305, Power retention performance calibration: Specifically, the power retention performance calibration aims to ensure the battery capacity of the hybrid mode under desert conditions, balancing power and energy consumption.

[0033] First, under full load as the test load, the test was conducted for 30 minutes under typical desert conditions such as crossing the herdsman's road, shoveling, washing pots, and riding the knife edge. The battery pack voltage, current and motor torque data were collected by the ETAS582.1 calibration data acquisition system, and the battery pack and motor temperature data were collected by the point thermometer at 1 minute interval. Secondly, statistical analysis was conducted on the motor discharge power curve and throttle opening change curve under different operating conditions. The average discharge power and peak discharge power for each operating condition were calculated. The average discharge power was used to assess normal energy consumption, and the peak discharge power was used to assess extreme power demand. Then, based on data on battery pack charging and discharging power, generator power, engine power, compressor power, and engine and generator efficiency, a power retention performance optimization model is established. The model inputs are operating condition type, throttle opening, and ambient temperature, and the outputs are engine start threshold and generator power distribution parameters. The engine start threshold is adjusted so that the engine starts generating electricity when the battery SOC is below 60%. The generator power distribution parameters are adjusted so that the generator output power prioritizes meeting the battery charging demand while taking into account the motor power demand, so that the vehicle's battery retention rate is not less than 80% under desert conditions. At the same time, the driver's subjective evaluation is taken into account power response speed, fuel consumption, and NVH performance to ensure that there is no obvious power lag, excessive fuel consumption, or abnormal noise.

[0034] S306, Feedback Performance Calibration: Specifically, the feedback performance calibration aims to optimize energy recovery efficiency in desert conditions while ensuring driving safety.

[0035] First, distinguish between coasting feedback and braking feedback. Define 3 to 5 coasting feedback levels according to the project's preset strategy. Level 1 is weak feedback and level 5 is strong feedback. Test different coasting feedback levels for each working condition, including crossing pastoral trails, going uphill, skidding, riding on sharp edges, and going downhill on sandy slopes. Use VECTOR1630A to test the motor feedback intensity of different levels online and record the correspondence between feedback torque and vehicle speed to ensure that the feedback torque decreases smoothly as the vehicle speed decreases. Secondly, when the coasting feedback power exceeds the maximum load capacity of the motor by more than 10%, the electro-hydraulic braking system is triggered to actively intervene. The timing of braking intervention is controlled by the brake pressure sensor. The intervention timing is set to 0.2 seconds before the feedback torque fails to meet the deceleration requirements, so as to ensure the stability of feedback performance and braking safety, and avoid abrupt deceleration caused by feedback interruption. Finally, for vehicles equipped with 4H and 4L modes, the feedback parameters for the two modes were calibrated respectively. The 4H mode is suitable for normal driving, with the feedback intensity set to gear 3-5. The 4L mode is suitable for low-speed traction, with the feedback intensity set to gear 1-2. This adapts the feedback performance to different desert four-wheel drive scenarios. The test process uses full load as a fixed load to ensure that the feedback experience is consistent in different modes.

[0036] S307, Thermal Management Performance Calibration: Specifically, thermal management performance calibration aims to ensure the thermal balance of various systems in high-temperature desert environments and avoid overheating failures.

[0037] First, preparatory work needs to be done before carrying out thermal management performance calibration. PT100 temperature sensors are installed on the head of the vehicle occupants, air conditioning vents, battery pack surface, motor controller, inverter and high and low temperature heat dissipation system pipelines, a total of 20 sensors are installed. The accuracy of sensor data acquisition is verified by a multi-functional environmental tester to ensure that the error does not exceed ±0.5℃. Check the sealing of the cooling pipes by injecting compressed air at 0.8–1.2 MPa into the cooling pipes using a pressure testing machine, holding the pressure for 30 minutes to ensure there are no leaks; Add R134a or R1234yf refrigerant to the air conditioning system according to the design standards, with an error of no more than 50 grams. Confirm that the water pump speed control logic of the battery pack thermal management system, the fan start / stop threshold of the high-temperature heat dissipation system, and the valve group switching strategy of the low-temperature heat dissipation system are in a state of pending calibration.

[0038] Then, in a high-temperature desert environment with an ambient temperature of no less than 38°C, the vehicle was fully loaded as the test load. A driver with more than 5 years of desert off-road experience operated the vehicle to simulate the driving style of a professional guide, including rapid acceleration, rapid deceleration, and long-term low-speed driving. The test included conditions such as idling to generate electricity, idling to cool down, crossing herdsmen's trails, climbing hills, washing pots, and riding on knife-edge terrain. Each condition was tested for 1 hour. Temperature sensors are used to collect coolant temperature, air conditioning vent temperature, passenger head temperature, and the temperature of the three-electric system (electric drive, electronic control, and electronic equipment) at 1-minute intervals. The cooling rate of each temperature parameter within 30 minutes is recorded to ensure that the coolant cooling rate is not less than 2℃ / min, the air conditioning vent temperature is maintained at 18-22℃, the passenger head temperature is maintained at 26-28℃, and the temperature of the three-electric system does not exceed 85℃. If an over-temperature alarm or over-temperature power limitation occurs, the thermal management system control parameters such as water pump speed, fan speed, and valve opening are adjusted. The water pump speed is adjusted by 100-200 r / min, the fan speed by 500-1000 r / min, and the valve opening by 10%-20%, until the thermal balance performance of the vehicle under high-temperature desert conditions meets the design specifications.

[0039] During the implementation of each calibration stage, a hybrid verification method combining virtual calibration and real vehicle testing was adopted simultaneously. Virtual calibration, based on operating condition data collected from real vehicles, builds a powertrain simulation model in Simulink to simulate vehicle performance under different parameter configurations, predicts parameter optimization directions, and reduces the number of real vehicle tests. Real vehicle testing, based on the prediction results of virtual calibration, verifies the effect of parameter optimization, collects data from each calibration stage, including torque output data, wheel slippage data, braking performance data, torque transfer response data, battery charging and discharging power data, motor feedback power data, and temperature data of each system, and optimizes the parameters of each calibration stage. Optimized parameters include inter-axle torque distribution ratio, ESP control parameters, torque transfer threshold, power preservation strategy parameters, feedback intensity parameters, and thermal management control parameters, ultimately adapting the pure electric and hybrid dual-mode powertrain system to desert operating conditions.

[0040] In summary, the calibration and matching test method for dual-mode off-road vehicles under desert conditions provided in this application, through systematic site selection, vehicle preparation, and multi-dimensional calibration, combined with hybrid verification of virtual calibration and real vehicle testing, achieves performance optimization of the dual-mode power system in the extreme desert environment. This method solves the problems of existing calibration tests lacking desert-specificity, low testing efficiency, and insufficient data collection. It improves the torque response speed of the vehicle under desert conditions, reduces mode switching delay, optimizes energy consumption control, and enhances safety performance, providing a scientifically feasible testing solution for the extreme environment adaptation of dual-mode off-road vehicles.

[0041] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A calibration and matching test method for a dual-mode off-road vehicle under desert conditions, specifically for off-road vehicles equipped with both pure electric and hybrid dual-mode drive, characterized in that... include: Select a test site suitable for desert conditions and deploy the equipment required for calibration testing; The calibration vehicle is prepared, inspected by the engineer, and then sent to the test site with the inspection record kept simultaneously. Torque chain calibration, inter-axle torque distribution calibration, ESP calibration, torque transfer calibration, power preservation performance calibration, feedback performance calibration, and thermal management performance calibration were carried out in sequence. Simultaneously, a hybrid verification method combining virtual calibration and real vehicle testing was adopted to collect data from each calibration stage and optimize the parameters of each calibration stage to adapt the pure electric and hybrid dual-mode power system to desert conditions.

2. The calibration and matching test method for a dual-mode off-road vehicle under desert conditions according to claim 1, characterized in that, The test site features typical desert terrain and a high-temperature climate. The equipment required for deployment and calibration testing includes: The test system was built using ETAS582.1 calibrated data acquisition, VECTOR1630A online data acquisition, VBOX, and gyroscope equipment; The testing equipment also includes a Hilta offline data acquisition system, a multi-functional environmental tester, an inclinometer, a laser rangefinder, and a GoPro action camera. The GoPro action camera is used to record the vehicle's driving posture, and the laser rangefinder is used to measure the slope of the ramp. Together, they complete the full-dimensional acquisition of working condition data and support the hybrid verification of virtual calibration and real vehicle testing.

3. The calibration and matching test method for a dual-mode off-road vehicle under desert conditions according to claim 1, characterized in that, The torque chain calibration includes: Measure the vehicle's curb weight, light load weight, half load weight and full load weight, and record the axle load distribution data simultaneously. Determine the benchmark ratio of axle torque distribution under horizontal sand conditions based on the axle load distribution data. Confirm the ESP software status and completely turn it off using a switch to eliminate interference from the ESP system on the torque output of the powertrain. For the vehicle's 4H and 4L four-wheel drive modes, torque loading parameters are set separately so that the torque loading slope and step size of the 4L mode are greater than those of the 4H mode. The torque output characteristics were tested at ten throttle openings: 10%, 20%...100%. Each opening point was tested three times, and subjective evaluations were conducted simultaneously to determine whether the torque output met the driver's power expectations for desert conditions.

4. The calibration and matching test method for a dual-mode off-road vehicle under desert conditions according to claim 1, characterized in that, The inter-shaft torque distribution calibration includes: Under flat sandy conditions, the test loads were set at the standard load, light load, half load and full load respectively. The acceleration process was tested under different throttle openings by switching between D and R gears, and the wheel slippage synchronization between the axles was observed. If the wheels on the axle slip out of sync, adjust the torque distribution ratio between the axles until the wheels on the axles slip out in the same way. Under desert slope conditions with different gradients, the above load and gear test process was repeated to capture the critical state of wheel slippage between the axles during the climbing process. Based on the slippage synchronization, the torque distribution ratio was adjusted to ensure that the power distribution between the axles under slope conditions is adapted to the adhesion characteristics of the sand.

5. The calibration and matching test method for a dual-mode off-road vehicle under desert conditions according to claim 1, characterized in that, The ESP calibration includes: Under conditions of flat sandy land, sandy slopes, herder trails, traversing the desert, brushing pots, and riding the knife edge, the test loads were set at the calibrated load, light load, half load, and full load to calibrate the braking performance, braking stability, and pedal feel, ensuring that the braking performance meets the vehicle design specifications. Simultaneously calibrate TCS performance parameters and test the vehicle stability during start-up acceleration, hill climbing, and getting out of trouble, so that the TCS function can be adapted to the soft desert road surface. For different ESP switch positions, the corresponding TCS and VDC performance parameters are calibrated to cover the needs of different desert driving scenarios. The gear positions include ON, shallow OFF, deep OFF, and completely OFF.

6. The calibration and matching test method for a dual-mode off-road vehicle under desert conditions according to claim 1, characterized in that, The torque transfer calibration includes: Based on the completion of torque chain calibration and ESP calibration, for the inter-wheel torque transfer, the coaxial single wheel slippage condition is simulated, and the torque distribution ratio of the non-slipping wheel is adjusted to achieve torque transfer to the non-slipping wheel; To address inter-axle torque transfer, a scenario of simultaneous slippage of two wheels on a single axle is simulated, and the torque distribution ratio of the other axle is adjusted to achieve cross-axle torque transfer. The test conditions cover cross-axle detachment in sandy areas, detachment on slopes, detachment on sharp edges, shoal crossings, pothole crossings, and crossing of herder's trails. The test loads include the calibration load, half load, and full load to ensure that the torque transfer response speed and distribution accuracy meet the design objective and subjective indicators.

7. The calibration and matching test method for a dual-mode off-road vehicle under desert conditions according to claim 1, characterized in that, The power retention performance calibration includes: Using full load as the test load, under typical desert conditions such as crossing the herdsman's road, shoveling, shoveling pots, and riding the knife edge, message data was collected through the ETAS582.1 calibration data acquisition system, and temperature data of key components were collected using a point thermometer. Statistical analysis of motor discharge power curves and throttle opening variation curves under different operating conditions; Based on data on battery pack charging and discharging power, generator power, engine power, compressor power, and engine and generator efficiency, a power retention performance optimization model is established. Relevant parameters are adjusted to ensure that the vehicle's power retention capability under desert conditions meets design requirements, while also taking into account power, energy consumption, and NVH performance.

8. The calibration and matching test method for a dual-mode off-road vehicle under desert conditions according to claim 1, characterized in that, The feedback performance calibration includes: Distinguish between coasting feedback and braking feedback, define coasting feedback levels according to the project's preset strategy, and test the motor feedback intensity of different levels under conditions such as crossing herdsmen's trails, rushing uphill, brushing pots, riding on knife edges, and descending sandy slopes. The VECTOR1630A is used to collect motor feedback power data online. When the coasting feedback power exceeds the motor's load capacity, the electro-hydraulic braking system is triggered to actively intervene and ensure the stability of feedback performance. For vehicles equipped with 4H and 4L modes, feedback parameters for the two modes were calibrated to adapt the feedback performance to different desert four-wheel drive scenarios. The test process used full load as a fixed load.

9. The calibration and matching test method for a dual-mode off-road vehicle under desert conditions according to claim 1, characterized in that, The following preparatory work needs to be done before carrying out thermal management performance calibration: Temperature sensors were placed on the head of the vehicle occupants, the air conditioning vents, the surface of the battery pack, key components of the three-electric system, and the pipelines of the high and low temperature heat dissipation system to verify the accuracy of sensor data acquisition. Check the cooling pipes for leaks; Add refrigerant to the air conditioning system according to the design standards, and confirm that the components of the battery pack thermal management system, high-temperature heat dissipation system, and low-temperature heat dissipation system are functioning normally, and that the software control logic is in a state of pending calibration.

10. The calibration and matching test method for a dual-mode off-road vehicle under desert conditions according to claim 9, characterized in that, The thermal management performance calibration includes: In a high-temperature desert environment with an ambient temperature of no less than 38℃, the vehicle was fully loaded and operated by a driver to simulate the driving style of a professional guide. The tests included stationary idling power generation, stationary idling cooling, crossing a herdsman's trail, climbing a slope, washing pots, and riding a knife edge. Temperature sensors are used to collect coolant temperature, air conditioning vent temperature, passenger head temperature, and the temperature of the three-electric system, and the cooling rate of each temperature parameter is statistically analyzed. If an over-temperature alarm or over-temperature power limitation occurs, adjust the thermal management system control parameters until the vehicle's thermal balance performance under high-temperature desert conditions meets the design specifications.

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