Object-oriented tracked vehicle dynamic model library modeling method

Abstract

The invention belongs to the technical field of one-dimensional simulation model modeling, and particularly relates to an object-oriented tracked vehicle power model library modeling method, which comprises the following steps of: firstly, establishing a tracked vehicle power model library modeling flow chart according to a demand model decomposed by a power architecture; decomposing the whole vehicle model library into a track and loading wheel library, an engine library, a transmission library, a transmission chain library, a hydraulic library and a simulation task working condition library; according to the invention, simulation of dynamic property, steering property and braking property of the tracked vehicle is realized. The tracked vehicle power model can be subjected to various single tests such as maximum vehicle speed, first-gear acceleration, second-gear acceleration, steering function, climbing, braking and the like. The model is parameterized modeling, and a user can set relevant parameters according to different vehicle models so as to simulate simulation of corresponding vehicle models. Therefore, the vehicle model provided by the invention has good reusability. According to the invention, multi-system integrated modeling and simulation of a control system, a mechanical power system, temperature control, hydraulic control and the like are realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of one-dimensional simulation model modeling, and specifically relates to an object-oriented modeling method for a tracked vehicle power model library, object-oriented mechanical, electrical, and hydraulic multi-system simulation modeling, and a vehicle system power performance model library mechanism. Background Art

[0002] Power performance, braking performance, and steering performance are the most important and basic performances of a vehicle. Usually, the final evaluation of power and braking performance levels can only be given after the actual vehicle road test. This not only takes a long time and is costly, but also makes the determination of the vehicle and various assembly plans, the selection of structural parameters, and the matching of the transmission system and the engine in the product design stage somewhat blind, which may cause the omission of better solutions, resulting in a waste of talent and material resources.

[0003] In view of the above problems, the present invention uses Modelica language to build a dynamic model library for tracked vehicles to solve the whole vehicle performance simulation problems such as tracked vehicle dynamic performance, braking performance and steering performance. The model library has the characteristics of modularization, hierarchy, standardization and parameterization, and the simulation model has strong interoperability and reusability. Summary of the invention

[0004] 1. Technical issues to be resolved

[0005] The technical problem to be solved by the present invention is that the modeling process of the power system, transmission system, hydraulic system, etc. of the tracked vehicle is a very complex electromechanical and hydraulic multi-system modeling process, which is time-consuming and brings many inconveniences to the research work, and the traditional single-domain modeling and simulation analysis tools are obviously not competent for the task of overall performance simulation analysis. In addition, considering the real-time dynamic performance of the tracked vehicle, it is also necessary to fully consider the impact of the control strategy on the vehicle system. Therefore, it is difficult to accurately analyze the coupling problem of multiple subsystems in different fields using a single tool, and the energy coupling of mechanical, electrical, hydraulic, and control cannot be considered.

[0006] (II) Technical solution

[0007] In order to solve the above technical problems, the present invention provides an object-oriented modeling method for a tracked vehicle power model library. A tracked vehicle power model library is developed by the method, and a real-time model of the whole vehicle is built based on the model library. The real-time model of the whole vehicle can realize the simulation of maximum vehicle speed, full throttle acceleration, maximum climbing grade, braking condition and steering condition.

[0008] According to the power transmission architecture of the tracked vehicle, the series and parallel relationship of each model component can be clearly seen, which is helpful to understand the working principle of the target system. In the process of model development, it is necessary to clarify the interface form of each component, so as to complete the logical relationship of the SysDeSim original model library. The vehicle model organized by the architecture diagram includes the engine and its control model, the gearbox and its control model, the track and road wheel model, the hydraulic steering model, the transmission chain model, the main reducer model, and also includes some basic models.

[0009] The tracked vehicle power model library modeling method comprises the following steps:

[0010] Step 1: According to the demand model of power structure decomposition, first establish the modeling flow chart of track vehicle power model library, and decompose the whole vehicle model library into track and road wheel library, engine library, transmission library, transmission chain library, hydraulic library and simulation task condition library;

[0011] Step 2: In the component modeling process, the basic components provided by the Modelica basic library and other commercial libraries are directly used. Due to the particularity of the actual mechanism system, some components that are not included in the Modelica basic library and commercial libraries are developed and constructed by ourselves;

[0012] When constructing the interface of components, the first thing is to classify the components of the same type, that is, mechanical and hydraulic components are classified into one category. The interfaces are divided into input interfaces and output interfaces. The interfaces are used to realize data transmission between components. The output interface of the previous component is connected to the input interface of the next component. The transmission between different types of components must ensure that they have the same interface. For example, since the hydraulic steering motor and the rotating element have the same rotary sub-interface, the hydraulic steering motor can be connected to the rotating element. The physical model of the same component is described by the equation group between its input interface and output interface. Parametric modeling is used when constructing components to improve the reusability of the model. Finally, the constructed components are encapsulated, and users only need to modify their parameters to use them in different vehicle system models.

[0013] The track and road wheel library includes a road wheel model, a steering model, a resistance model, and a vehicle body model; in the road wheel model, the ground force on the track is realized by six road wheels on the left and right, and the influence of non-road wheels and track deformation on the force is ignored; the resistance model includes ground friction coefficient, wind resistance coefficient, steering resistance, and ramp resistance calculation; the vehicle body model calculates the vehicle speed and acceleration by integrating the vehicle driving force with the ground reaction force and resistance; the steering model calculates the vehicle steering angular velocity through the driving force and steering resistance.

[0014] In the engine library, the engine is a device that provides power for the vehicle and determines the vehicle's power, economy, stability and environmental protection; the engine ignites diesel in a sealed cylinder, and the generated gas pushes the piston to do work, which is then converted into mechanical energy.

[0015] The transmission library includes a transmission model, a speed ratio model, a rotational inertia, an efficiency model and a TCU control model. The TCU receives in real time the engine load signal, the required vehicle speed signal of the simulation task condition and the real-time vehicle speed of the track and road wheel model, and realizes the change of the transmission ratio according to different shifting strategies; the transmission shifting principle: the forward gear starts in 1st gear by default, the transmission shifts up when the vehicle is in an accelerating state and the real-time vehicle speed is greater than the upshift speed, and the transmission downshifts when the vehicle is in a decelerating state and the real-time vehicle speed is less than the downshift speed.

[0016] The transmission chain model in the transmission chain library includes rotational inertia, a reducer, a hydraulic torque converter, a brake module, and a planetary gear mechanism to achieve the distribution of engine input power.

[0017] The steering model in the vehicle model is realized through the hydraulic steering system model, which includes a hydraulic pump (variable volume), a cavity, a liquid storage tank, a pressure relief valve, and a one-way valve; the steering angle signal of the steering model is given by the driver's steering signal, which is input into the hydraulic steering system model to control the power output of the hydraulic steering system model; wherein, the interface of the hydraulic steering system model is: the driver's steering signal u, connected to the driver's steering interface, the steering pump power input interface flange_a, connected to the pump_steer of the transmission chain, and the steering motor power output interface flange_b, connected to the motor'_steer of the transmission chain.

[0018] The simulation task condition library includes vehicle slip control, accelerator pedal control, brake pedal control, and vehicle simulation condition control (target vehicle speed, slope).

[0019] Step 3: After the component libraries including the track and road wheel library, engine library, transmission library, drive chain library, hydraulic library and simulation task condition library are tested, the model of each working condition of the whole vehicle is built by using the above model library with reference to the tracked vehicle architecture to obtain the full throttle acceleration working condition model of the whole vehicle. By using the commercial software of the Modelica language to set the simulation step size and simulation accuracy, the real-time simulation calculation of each working condition model is realized to simulate the power transmission and energy loss of the actual operating conditions of the tracked vehicle.

[0020] (III) Beneficial effects

[0021] Compared with the prior art, the present invention realizes the simulation of the power, steering and braking of the tracked vehicle. For the tracked vehicle power model, a variety of single tests such as maximum speed, 1st gear acceleration, 2nd gear acceleration, steering function, climbing and braking can be performed. This model is a parametric modeling, and the user can set the relevant parameters according to different vehicle models to simulate the simulation of the corresponding vehicle model. Therefore, the vehicle model of the present invention has good reusability. The present invention realizes the integrated modeling and simulation of multiple systems such as control system, mechanical power system, temperature control, hydraulic control, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a diagram of the power transmission structure of the tracked vehicle of the present invention;

[0023] Figure 2 A modeling flow chart of a tracked vehicle power model library of the present invention;

[0024] Figure 3 The crawler track and road wheel model of the present invention;

[0025] Figure 4 is the transmission control model of the present invention;

[0026] Figure 5 The transmission chain model of the present invention;

[0027] Figure 6 It is the hydraulic steering model of the present invention;

[0028] Figure 7 It is a simulation task working condition model of the present invention;

[0029] Figure 8 This is the full throttle acceleration model of the whole vehicle of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, content, and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below in conjunction with the accompanying drawings and examples.

[0031] In order to solve the above technical problems, the present invention provides an object-oriented modeling method for a tracked vehicle power model library. A tracked vehicle power model library is developed by the method, and a real-time model of the whole vehicle is built based on the model library. The real-time model of the whole vehicle can realize the simulation of maximum vehicle speed, full throttle acceleration, maximum climbing grade, braking condition and steering condition.

[0032] According to the power transmission architecture of the tracked vehicle, the series and parallel relationship of each model component can be clearly seen, which is helpful to understand the working principle of the target system. In the process of model development, it is necessary to clarify the interface form of each component, so as to complete the logical relationship of the SysDeSim original model library. The vehicle model organized by the architecture diagram includes the engine and its control model, the gearbox and its control model, the track and road wheel model, the hydraulic steering model, the transmission chain model, the main reducer model, and also includes some basic models.

[0033] The tracked vehicle power model library modeling method comprises the following steps:

[0034] Step 1: According to the demand model of power structure decomposition, first establish the modeling flow chart of track vehicle power model library, and decompose the whole vehicle model library into track and road wheel library, engine library, transmission library, transmission chain library, hydraulic library and simulation task condition library;

[0035] Step 2: In the component modeling process, the basic components provided by the Modelica basic library and other commercial libraries are directly used. Due to the particularity of the actual mechanism system, some components that are not included in the Modelica basic library and commercial libraries are developed and constructed by ourselves;

[0036] When constructing the interface of components, the first thing is to classify the components of the same type, that is, mechanical and hydraulic components are classified into one category. The interfaces are divided into input interfaces and output interfaces. The interfaces are used to realize data transmission between components. The output interface of the previous component is connected to the input interface of the next component. The transmission between different types of components must ensure that they have the same interface. For example, since the hydraulic steering motor and the rotating element have the same rotary sub-interface, the hydraulic steering motor can be connected to the rotating element. The physical model of the same component is described by the equation group between its input interface and output interface. Parametric modeling is used when constructing components to improve the reusability of the model. Finally, the constructed components are encapsulated, and users only need to modify their parameters to use them in different vehicle system models.

[0037] The track and road wheel library includes a road wheel model, a steering model, a resistance model, and a vehicle body model; in the road wheel model, the ground force on the track is realized by six road wheels on the left and right, and the influence of non-road wheels and track deformation on the force is ignored; the resistance model includes ground friction coefficient, wind resistance coefficient, steering resistance, and ramp resistance calculation; the vehicle body model calculates the vehicle speed and acceleration by integrating the vehicle driving force with the ground reaction force and resistance; the steering model calculates the vehicle steering angular velocity through the driving force and steering resistance.

[0038] In the engine library, the engine is a device that provides power for the vehicle and determines the vehicle's power, economy, stability and environmental protection; the engine ignites diesel in a sealed cylinder, and the generated gas pushes the piston to do work, which is then converted into mechanical energy.

[0039] The transmission library includes a transmission model, a speed ratio model, a rotational inertia, an efficiency model and a TCU control model. The TCU receives in real time the engine load signal, the required vehicle speed signal of the simulation task condition and the real-time vehicle speed of the track and road wheel model, and realizes the change of the transmission ratio according to different shifting strategies; the transmission shifting principle: the forward gear starts in 1st gear by default, the transmission shifts up when the vehicle is in an accelerating state and the real-time vehicle speed is greater than the upshift speed, and the transmission downshifts when the vehicle is in a decelerating state and the real-time vehicle speed is less than the downshift speed.

[0040] The transmission chain model in the transmission chain library includes rotational inertia, a reducer, a hydraulic torque converter, a brake module, and a planetary gear mechanism to achieve the distribution of engine input power.

[0041] The steering model in the vehicle model is realized through the hydraulic steering system model, which includes a hydraulic pump (variable volume), a cavity, a liquid storage tank, a pressure relief valve, and a one-way valve; the steering angle signal of the steering model is given by the driver's steering signal, which is input into the hydraulic steering system model to control the power output of the hydraulic steering system model; wherein, the interface of the hydraulic steering system model is: the driver's steering signal u, connected to the driver's steering interface, the steering pump power input interface flange_a, connected to the pump_steer of the transmission chain, and the steering motor power output interface flange_b, connected to the motor'_steer of the transmission chain.

[0042] The simulation task condition library includes vehicle slip control, accelerator pedal control, brake pedal control, and vehicle simulation condition control (target vehicle speed, slope).

[0043] Step 3: After the component libraries including the track and road wheel library, engine library, transmission library, drive chain library, hydraulic library and simulation task condition library are tested, the model of each working condition of the whole vehicle is built by using the above model library with reference to the tracked vehicle architecture to obtain the full throttle acceleration working condition model of the whole vehicle. By using the commercial software of the Modelica language to set the simulation step size and simulation accuracy, the real-time simulation calculation of each working condition model is realized to simulate the power transmission and energy loss of the actual operating conditions of the tracked vehicle.

[0044] Example 1

[0045] This embodiment provides an object-oriented modeling method for a tracked vehicle power model library. The principle is as follows: Figures 1 to 8 As shown;

[0046] Slip rate calculation formula:

[0047] slip = v_s / v vehicle

[0048] v_s=v vehicle -v_r

[0049] v_r=w×r wheel

[0050] Among them, v_s is the slip velocity, v vehicle is the vehicle speed, v_r is the rolling linear velocity of the road wheel; r wheel is the radius of the road wheel;

[0051] Calculation of maximum friction and actual friction:

[0052] The maximum friction that a road wheel can provide depends on the coefficient of friction between the ground and the track and the load:

[0053] f max =f z ×mue act

[0054] Among them, f z is the dynamic load of the corresponding road wheel; act is the actual friction coefficient; the actual friction provided by the track, and the driving or braking force generated by the road wheel f Drive :

[0055] f Drive =min(slip×k,f max )

[0056] The relationship between the engine's mean effective pressure (BMEP, FMEP) and torque is as follows:

[0057] N-stroke engine:

[0058]

[0059] Where: BMEP is the brake mean effective pressure (bar); FMEP is the friction mean effective pressure (bar); T out is the engine output torque (Nm); T fric is the engine friction torque (Nm); V is the engine effective volume (L);

[0060] The engine output torque is calculated as follows:

[0061] T out =T maxc ·load+T minc (1-load)

[0062] Among them, T maxc and T minc is the corrected maximum torque and minimum torque;

[0063] The maximum torque is corrected according to the following environmental conditions:

[0064]

[0065] Among them, T maxfile is the maximum engine torque (Nm) read from the data table; ρ air is the ambient air density (kg / m 3 );ρ ref is the reference ambient air density (kg / m 3 );T amb is the ambient air temperature (K); T ref is the reference ambient temperature (degC);

[0066] The actual fuel consumption of the engine is calculated as follows:

[0067] cons=cons file ·(1+kstart)·efcons

[0068] Among them, cons is the actual fuel consumption; cons is the actual fuel consumption; file is the value read from the data table; kstart is the excessive consumption when the engine starts; efcons is the low temperature effect (when there is no temperature effect, the value is 1);

[0069] In driving mode, the effective load effload depends on the input type of the model port;

[0070] The driver's acceleration signal is between (0-1)

[0071] effload=load

[0072] Engine power (unit: kW)

[0073]

[0074] Total power success rate (unit: kW)

[0075]

[0076] Engine torque (unit: Nm)

[0077]

[0078] Among them, T maxis the maximum engine torque (Nm); EffT is the transmission efficiency;

[0079] In addition, the engine module has a built-in heat exchange interface, which can realize engine temperature control through an external temperature control unit, and simulate the engine performance status at different temperatures;

[0080] The power flow relationship of the internal transmission chain: the power is input by the engine and then diverted to the power loss module (hydraulic), steering module and torque converter (the main load of engine power output);

[0081] 1) A portion of the power is diverted to the power loss module to simulate the torque loss during the power transmission process;

[0082] 2) The power diverted to the steering module flows into the steering module through the pump_steer interface, flows back to the transmission chain model through the motor_steer after passing through the steering module, and then transmits the power to the left and right planetary gear converging mechanisms;

[0083] 3) The power from the torque converter flows into the gearbox through planetaryin, and then flows back to the transmission chain model through planetaryout. The power is divided into two branches to the left and right planetary gear converging mechanisms;

[0084] The left and right planetary gear converging mechanisms couple the transmission power of the gearbox and the hydraulic steering power, and then transmit the power to the left and right transmission shafts respectively; this mechanism can realize the steering function of the vehicle through the power coupling of the left and right planetary gears;

[0085] At the same time, brakes are connected to the left and right output shafts to realize the braking function of the vehicle;

[0086] In the simulation task condition, the driver model interpolates the required vehicle speed and the real-time vehicle speed input through the bus and processes it into an acceleration or deceleration signal s through PI control:

[0087] s=k×Δv+T×Int(Δv)

[0088] Δv=v desired -v

[0089] s acc =s>0? s:0

[0090] s brake =s<0? -s:0

[0091] Among them, s acc and brake They are respectively the accelerator pedal and brake pedal travel signals; v desired is the required vehicle speed, v is the actual vehicle speed; k is the proportional coefficient of the PI controller, and T is the time constant of the PI controller.

[0092] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An object-oriented modeling method for a tracked vehicle power model library, characterized in that: The tracked vehicle power model library modeling method comprises the following steps: Step 1: According to the demand model of power structure decomposition, first establish the modeling flow chart of track vehicle power model library, and decompose the whole vehicle model library into track and road wheel library, engine library, transmission library, transmission chain library, hydraulic library and simulation task condition library; Step 2: In the component modeling process, the basic components provided by the Modelica basic library and commercial libraries are directly used. For the components not included in the Modelica basic library and commercial libraries, they are developed and constructed by ourselves. When building the interface of components, first of all, the same type of components, that is, mechanical and hydraulic are classified into one category, and the interface is divided into input interface and output interface. The interface is used to realize data transmission between components, and the output interface of the previous component is connected to the input interface of the next component; the transmission between different types of components must ensure that they have the same interface; the physical model of the same component is described by the equation group between its input interface and output interface; parametric modeling is used when building components to improve the reusability of the model; finally, the constructed components are encapsulated, and users only need to modify their parameters to use them in different vehicle system models; Step 3: After the component libraries including the track and road wheel library, engine library, transmission library, drive chain library, hydraulic library and simulation task condition library are tested, the working condition models of the whole vehicle are built by using the above model libraries with reference to the tracked vehicle architecture. The simulation step size and simulation accuracy are set by using commercial software in the Modelica language to realize real-time simulation calculation of each working condition model and simulate the power transmission and energy loss of the actual operating conditions of the tracked vehicle.

2. The object-oriented modeling method for a tracked vehicle power model library according to claim 1, characterized in that: In step 2, the transmission between different types of components must ensure that they have the same interface. For example, since the hydraulic steering motor and the rotating element have the same rotational pair interface, the hydraulic steering motor can be connected to the rotating element.

3. The object-oriented modeling method for a tracked vehicle power model library according to claim 1, characterized in that: The track and road wheel library includes a road wheel model, a steering model, a resistance model, and a vehicle body model; in the road wheel model, the ground force on the track is realized by six road wheels on the left and right, and the influence of non-road wheels and track deformation on the force is ignored; the resistance model includes ground friction coefficient, wind resistance coefficient, steering resistance, and ramp resistance calculation; the vehicle body model calculates the vehicle speed and acceleration by integrating the vehicle driving force with the ground reaction force and resistance; the steering model calculates the vehicle steering angular velocity through the driving force and steering resistance.

4. The object-oriented modeling method for a tracked vehicle power model library according to claim 1, characterized in that: In the engine library, the engine is a device that provides power for the vehicle and determines the vehicle's power, economy, stability and environmental protection; the engine ignites diesel in a sealed cylinder, and the generated gas pushes the piston to do work, which is then converted into mechanical energy.

5. The object-oriented modeling method for a tracked vehicle power model library according to claim 1, characterized in that: The transmission library includes a transmission model, a speed ratio model, a rotational inertia, an efficiency model and a TCU control model. The TCU receives in real time the engine load signal, the required vehicle speed signal of the simulation task condition and the real-time vehicle speed of the track and road wheel model, and realizes the change of the transmission ratio according to different shifting strategies; the transmission shifting principle: the forward gear starts in 1st gear by default, the transmission shifts up when the vehicle is in an accelerating state and the real-time vehicle speed is greater than the upshift speed, and the transmission downshifts when the vehicle is in a decelerating state and the real-time vehicle speed is less than the downshift speed.

6. The object-oriented tracked vehicle power model library modeling method according to claim 1, characterized in that: The transmission chain model in the transmission chain library includes rotational inertia, a reducer, a hydraulic torque converter, a brake module, and a planetary gear mechanism to achieve the distribution of engine input power.

7. The object-oriented modeling method for a tracked vehicle power model library according to claim 1, characterized in that: The steering model in the vehicle model is realized through the hydraulic steering system model, which includes a hydraulic pump, a cavity, a fluid storage tank, a pressure relief valve, and a one-way valve; the steering angle signal of the steering model is given by the driver's steering signal, which is input into the hydraulic steering system model to control the power output of the hydraulic steering system model; wherein, the interface of the hydraulic steering system model is: the driver's steering signal u, connected to the driver's steering interface, the steering pump power input interface flange_a, connected to the pump_steer of the transmission chain, and the steering motor power output interface flange_b, connected to the motor'_steer of the transmission chain.

8. The object-oriented modeling method for a tracked vehicle power model library according to claim 1, characterized in that: The simulation task condition library includes vehicle slip control, accelerator pedal control, brake pedal control, and vehicle simulation condition control.

9. The object-oriented modeling method for a tracked vehicle power model library according to claim 1, characterized in that: A tracked vehicle dynamic model library is developed through the method, and a real-time model of the whole vehicle is built based on the model library. The real-time model of the whole vehicle can realize the simulation of maximum vehicle speed, full throttle acceleration, maximum climbing grade, braking condition and steering condition.

10. The object-oriented modeling method for tracked vehicle power model library according to claim 1, characterized in that: According to the power transmission architecture of the tracked vehicle, the series and parallel relationship of each model component can be clearly seen, which is helpful to understand the working principle of the target system. In the process of model development, it is necessary to clarify the interface form of each component, so as to complete the logical relationship of the SysDeSim original model library. The vehicle model organized by the architecture diagram includes the engine and its control model, the gearbox and its control model, the track and road wheel model, the hydraulic steering model, the transmission chain model, and the main reducer model.

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