CN111651849A - Automobile real-time dynamics modular modeling method and device and storage medium - Google Patents
Automobile real-time dynamics modular modeling method and device and storage medium Download PDFInfo
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Abstract
The invention discloses a modular modeling method for real-time dynamics of an automobile, which is used for acquiring the characteristics of mechanical parts of elements in a system to be processed and generating different modules according to the characteristics of the different mechanical parts. The elastic characteristic elements and the rigid body elements are modeled by elastic constraint blocks and rigid body blocks, and other elements are modeled by position blocks and force-moment blocks. The elastic constraint block and the rigid body block realize isolation and decoupling of a whole vehicle dynamic system, generation of an algebraic differential equation is effectively avoided, established models are ordinary differential equations and meet the requirement of simulation instantaneity, the position block and the force-moment block help to establish layered modular model modules, corresponding modules in real object replacement models of different levels can be conveniently realized, real object in-loop simulation of various levels of the vehicle is realized, and the requirement of simulation accuracy is met. The invention solves the problem that the current automobile dynamics simulation model can not accurately realize the verification of the intelligent driving motion control algorithm in real time.
Description
Technical Field
The invention relates to the field of automobile dynamics simulation modeling, in particular to an automobile dynamics modeling method for intelligent automobile motion control virtual verification.
Background
Vehicle motion control is one of the core technologies of intelligent driving, and all major host manufacturers persist in autonomous development. The method comprises the steps of independently developing a motion control algorithm, firstly establishing a vivid automobile real-time dynamics modular model, and testing and verifying the control algorithm in the simulation stages of the model in a ring, a hardware in the ring and a driving simulator in the ring.
Because an automobile real-time dynamics model needs to be established in verification of an intelligent driving motion control algorithm, but a part of systems, assemblies and components which are difficult to model exist in an automobile and are difficult to meet the requirement of hardware-in-the-loop simulation, most of the models are modularized only at a system level, and model modules corresponding to different levels of real objects are difficult to close as required for hardware-in-the-loop simulation of each level of the automobile due to the fact that the current simulation model is difficult to accurately verify the intelligent driving motion control algorithm.
Also, since the vehicle is a complex mechanical system, the various systems, assemblies, components are coupled to one another. Common multi-body dynamics software such as Adams and the like is modeled by a topological automatic derivation dynamic equation of a mechanical system, the model precision is high, but the established vehicle dynamic model equation is generally an algebraic differential equation set. At present, the numerical method for solving the algebraic differential equation is far less mature than the initial value problem of the ordinary differential equation. When in solution, the constraint equation in the algebraic differential equation can lead the state variables of the system to be not decoupled, the solution efficiency is extremely low, and the requirement of simulation instantaneity is difficult to meet.
In contrast, the current automobile dynamics simulation model cannot accurately realize the verification of the intelligent driving motion control algorithm in real time, and a method for accurately simulating the automobile power condition in real time is urgently needed in actual production.
Disclosure of Invention
The invention provides a modular modeling method, a device, a storage medium and terminal equipment for real-time dynamics of an automobile, and aims to solve the problem that the current automobile dynamics model cannot meet the real-time accuracy requirement of simulation easily.
In order to achieve the above object, an embodiment of the present invention provides a modular modeling method for real-time dynamics of an automobile, including:
acquiring the characteristics of mechanical parts of each element in a system to be processed;
if the mechanical part characteristic of the element is elastic, an elastic constraint block is generated, and the elastic constraint block takes the position form of the adjacent module as input and outputs force or torque;
generating a rigid block by taking the force or moment of the adjacent module or external connection as input and outputting the shape if the mechanical property of the element is rigid body property, wherein the rigid body blocks are isolated by elastic restraint blocks;
generating a position block if the mechanical part characteristic of the element is kinematic property, wherein the position block takes the position form of the adjacent module as input and outputs the position form;
the mechanical component properties of the element are static, which then generates a force-torque block that takes as input a force or torque of the adjoining module or of the external connection and outputs the force or torque.
Compared with the prior art, the real-time dynamics modularization modeling method for the automobile, disclosed by the invention, adopts the elastic constraint block to isolate and decouple a complex complete automobile dynamics system into a series of dynamics subsystem modules. "isolated" means that the complex mechanical vehicle dynamics model is isolated into individual sub-modules; "decoupled" means that each sub-module can be solved independently. Elastic constraining masses differ from the constraining pairs defined in rigid body dynamics in that their relationship to the connected rigid body is the configuration of the input rigid body mass, the output force or torque. For example, the most typical elastic restraint mass is spring damping, which calculates an elastic restraining force or moment from the deformation and velocity between the rigid bodies to which it is attached. According to the interface definition of the elastic constraint block module, different rigid bodies are isolated and decoupled through the elastic constraint block, and a constraint equation (algebraic equation) cannot be generated. The rigid body blocks are modules which take the force or moment of the adjacent elastic constraint blocks and force-moment block modules or the external force or moment as input and output configuration, and when each rigid body block in the system is isolated by the elastic constraint blocks, each rigid body is taken as the center, and the acting force of the elastic constraint blocks and the force-moment block modules which are connected with the rigid body blocks at the periphery is added, dynamic equations are independently written in series, so that the isolation and decoupling of the system are completed, and the established equations are ordinary differential equations. The elastic constraint block is an interface of the model, the complex model is decomposed into a series of independent sub-modules to be solved, and the established model equations are all ordinary differential equations. Because a large number of elastic elements such as suspensions, bushes and the like exist on the automobile, conditions are provided for isolation and decoupling of the model. The method can effectively avoid generating algebraic differential equations, and the established models are ordinary differential equations, thereby meeting the requirement of simulation instantaneity.
In addition, the invention provides the concepts of the position block and the force-moment block, the position block is a system module with input and output in the shape of position, the input and output of the interface are in a steady-state kinematic relationship, and the difference between the position block and the rigid block mainly lies in that the position block is only a steady-state system, and the rigid block is a dynamic system. The force-moment block is a module system with input and output of force or moment, and the input and output of the module system are in a steady static relation. The position block and the force-moment block are divided from the rigid body block and the elastic constraint block, and are extensions of the rigid body block and the elastic constraint block concept. In practical systems, the configuration block and the force-moment block are often connected in series. In an actual automobile system, a plurality of automobile assemblies and component modules only play steady-state kinematic or static functions between the rigid block and the elastic constraint block, and the assemblies and the components do not influence the isolation of the model but do not belong to the types of the elastic constraint block and the rigid block. The modeling of other elements is realized through the position block and the force-moment block, and the modular modeling of all assemblies and parts in the model is realized. The invention provides the concepts of an elastic constraint block, a rigid block, a position block and a force-moment block, wherein the four modules form a basic dynamics functional module of a complex automobile model, and an automobile real-time dynamics model modeling method is established on the basis. The boundary of the established layered modular model module has clear definition, and can be convenient for real objects of different levels to replace corresponding modules in the model, so that the real object in-loop simulation of various levels of the automobile is realized, the requirement of simulation accuracy is met, and the problem that a real-time accurate simulation method for the automobile power condition is lacked in actual production is solved.
Further, the automobile real-time dynamics modular modeling method further comprises the step of constructing an electric control unit model through a sensing model, a strategy model and an actuator model according to the functional characteristics.
In a preferred embodiment of the invention, a modeling method of an electric control unit model in an automobile dynamics model is provided. At present, motion control commands of intelligent automobiles, such as steering wheel angles, braking deceleration and the like, are all used for sending control commands to execution electric control units such as Electric Power Steering (EPS), an electronic stability control program (ESP), a central control unit (VCU) of an electric vehicle/an Engine Management System (EMS) of a fuel vehicle and the like to realize the control of the transverse and longitudinal motion of the vehicle. However, most of the existing commercial real-time dynamics software lacks an execution electronic control unit model of an intelligent driving controller such as an Electric Power Steering (EPS) and an Electronic Stability Program (ESP), and it is difficult to effectively respond to an instruction of the intelligent driving control unit and simulate behavior characteristics of the execution electronic control unit. Meanwhile, in verification of an intelligent driving motion control algorithm, hardware-in-loop simulation needs to be performed on systems, assemblies and components which are difficult to model of an automobile part, most of current real-time dynamics commercial software such as CarSim, veDYNA and the like is modularized only at a system level, and model modules corresponding to different levels of real objects are difficult to close as required, so that the models are used for hardware-in-loop simulation of each level of the automobile. The invention provides an automobile dynamics modeling framework and method for intelligent automobile motion control, which comprise an automobile dynamics model and an execution electric control unit model for motion control. The intelligent driving motion control electric control execution unit model provides a sensor model, a strategy model and an actuator model, and solves the problem that the existing automobile dynamics model lacks an electric control unit model.
Further, the transfer function of the actuator model is
In the formula, K is the gain between the control quantity and the electric control signal, and tau is the dynamic response time of the actuating mechanism.
In a preferred embodiment of the invention, a transfer function of the actuator model is given. In practical engineering, actuators of electric control units such as an Electric Power Steering (EPS) and an electronic stability control program (ESP) are difficult to accurately model in real time. In the electric control unit model, the actuator model adopts a simplified function model. Considering the dynamic response time of the actuator in the actual process, the transfer function of the actuator model is
The problem of actuator modeling of executing electric control units such as an Electric Power Steering (EPS) and an electronic stability control program (ESP) is solved.
In order to achieve the above object, an embodiment of the present invention further provides a modular modeling apparatus for real-time dynamics of an automobile, including:
the mechanism characteristic acquisition unit is used for acquiring the mechanism part characteristics of each element in the system to be processed;
the elastic constraint block generating unit is used for generating an elastic constraint block for an element with the elastic characteristic as the characteristic of the mechanism part, and the elastic constraint block takes the position form of the adjacent module as input and outputs force or moment;
a rigid body block generation unit for generating a rigid body block, which outputs a shape of a site with a force or a moment of an adjoining module or an external connection as an input, for an element whose mechanical member characteristic is a rigid body characteristic, the rigid body block being isolated from each other by elastic restraint blocks;
a bit pattern block generation unit for generating a bit pattern block for an element whose mechanical part characteristic is a kinematic property, the bit pattern block having bit patterns of adjoining modules as an input and outputting the bit pattern;
and the force-moment block generating unit is used for generating a force-moment block for an element with the static property of the mechanism part, and the force-moment block takes the force or the moment of the adjacent module or the external module as input and outputs the force or the moment.
Further, the modular modeling device for real-time dynamics of the automobile further comprises: and the electric control module generating unit is used for constructing an electric control unit model through the sensing model, the strategy model and the actuator model according to the functional characteristics.
In order to achieve the above object, an embodiment of the present invention further provides a computer-readable storage medium, where the computer-readable storage medium includes a stored computer program; wherein the computer program controls the device in which the computer readable storage medium is located to execute the modular modeling method for real-time dynamics of the automobile according to any one of the preceding embodiments when running.
In order to achieve the above object, an embodiment of the present invention further provides a terminal device, which includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, where the processor, when executing the computer program, implements the modular modeling method for real-time dynamics of an automobile according to any one of the foregoing embodiments.
Compared with the prior art, the automobile real-time dynamics modularization modeling method, the device and the storage medium disclosed by the invention have the advantages that the elastic constraint block is adopted to isolate and decouple a complex whole automobile dynamics system into a series of dynamics subsystem modules. "isolated" means that the complex mechanical vehicle dynamics model is isolated into individual sub-modules; "decoupled" means that each sub-module can be solved independently. The isolation decoupling of the whole vehicle dynamic system is realized through the elastic constraint block and the rigid body block, the generation of algebraic differential equations is effectively avoided, the established models are ordinary differential equations, and the requirement of simulation instantaneity is met. The modeling of the assembly and the component which only play the role of steady-state kinematics or statics in an actual automobile system and do not influence the isolation of the model but do not belong to the types of elastic constraint blocks and rigid body blocks is realized through the position block and the force-moment block. The basic dynamic function module of the complex automobile model is formed by four types of modules, the boundary of the established layered modular model module has definite definition, corresponding modules in the model can be conveniently replaced by real objects of different levels, real object in-loop simulation of various levels of the automobile is realized, and the requirement on simulation accuracy is met. The invention solves the problem that the current automobile dynamics simulation model can not accurately realize the verification of the intelligent driving motion control algorithm in real time, and provides a method for accurately simulating the automobile power condition in real time.
Drawings
FIG. 1 is a flow chart of one embodiment of a modular modeling method for real-time dynamics of an automobile of the present invention;
FIG. 2 is a diagram illustrating the definition of elastic constraints in an embodiment of the modular modeling method for real-time dynamics of an automobile of the present invention;
FIG. 3 is an isolation and decoupling schematic diagram of an elastic constraint block in an embodiment of a modular modeling method for real-time dynamics of an automobile of the present invention;
FIG. 4 is a diagram illustrating an exemplary calculation of elastic constraint mass forces in an embodiment of a modular modeling method for real-time dynamics of an automobile according to the present invention;
FIG. 5 is a diagram illustrating the definition of rigid blocks in an embodiment of the modular modeling method for real-time dynamics of an automobile of the present invention;
FIG. 6 is a diagram illustrating the definition of a configuration block in an embodiment of the modular modeling method for real-time dynamics of an automobile of the present invention;
FIG. 7 is a diagram illustrating the definition of force-moment blocks in an embodiment of the modular modeling method for real-time dynamics of an automobile of the present invention;
FIG. 8 is a diagram of a modular dynamics model of a steering system in an embodiment of a modular modeling method of real-time dynamics of an automobile of the present invention;
FIG. 9 is a diagram of a model of vehicle dynamics in another embodiment of the modular modeling method of vehicle real-time dynamics of the present invention;
FIG. 10 is a diagram of an overall intelligent driving motion control virtual verification modeling architecture according to another embodiment of the modular modeling method for real-time dynamics of an automobile of the present invention;
FIG. 11 is a schematic diagram of a modeling architecture of an intelligent driving motion control execution electronic control unit in another embodiment of the modular modeling method for real-time dynamics of the automobile of the present invention;
FIG. 12 is a block diagram of an embodiment of a modular modeling apparatus for real-time dynamics of an automobile according to the present invention;
fig. 13 is a block diagram of a terminal device according to an embodiment of the present invention.
Detailed Description
As shown in fig. 1, an embodiment of the present invention provides a modular modeling method for real-time dynamics of an automobile, including:
acquiring the characteristics of mechanical parts of each element in a system to be processed;
if the mechanical part characteristic of the element is elastic, an elastic constraint block is generated, and the elastic constraint block takes the position form of the adjacent module as input and outputs force or torque;
generating a rigid block by taking the force or moment of the adjacent module or external connection as input and outputting the shape if the mechanical property of the element is rigid body property, wherein the rigid body blocks are isolated by elastic restraint blocks;
generating a position block if the mechanical part characteristic of the element is kinematic property, wherein the position block takes the position form of the adjacent module as input and outputs the position form;
the mechanical component properties of the element are static, which then generates a force-torque block that takes as input a force or torque of the adjoining module or of the external connection and outputs the force or torque.
Compared with the prior art, the real-time dynamics modularization modeling method for the automobile, disclosed by the invention, adopts the elastic constraint block to isolate and decouple a complex complete automobile dynamics system into a series of dynamics subsystem modules. "isolated" means that the complex mechanical vehicle dynamics model is isolated into individual sub-modules; "decoupled" means that each sub-module can be solved independently. Elastic constraining masses differ from the constraining pairs defined in rigid body dynamics in that their relationship to the connected rigid body is the configuration of the input rigid body mass, the output force or torque. For example, the most typical elastic restraint mass is spring damping, which calculates an elastic restraining force or moment from the deformation and velocity between the rigid bodies to which it is attached. According to the interface definition of the elastic constraint block module, different rigid bodies are isolated and decoupled through the elastic constraint block, and a constraint equation (algebraic equation) cannot be generated. The rigid body blocks are modules which take the force or moment of the adjacent elastic constraint blocks and force-moment block modules or the external force or moment as input and output configuration, and when each rigid body block in the system is isolated by the elastic constraint blocks, each rigid body is taken as the center, and the acting force of the elastic constraint blocks and the force-moment block modules which are connected with the rigid body blocks at the periphery is added, dynamic equations are independently written in series, so that the isolation and decoupling of the system are completed, and the established equations are ordinary differential equations. The elastic constraint block is an interface of the model, the complex model is decomposed into a series of independent sub-modules to be solved, and the established model equations are all ordinary differential equations. Because a large number of elastic elements such as suspensions, bushes and the like exist on the automobile, conditions are provided for isolation and decoupling of the model. The method can effectively avoid generating algebraic differential equations, and the established models are ordinary differential equations, thereby meeting the requirement of simulation instantaneity.
In addition, the invention provides the concepts of the position block and the force-moment block, the position block is a system module with input and output in the shape of position, the input and output of the interface are in a steady-state kinematic relationship, and the difference between the position block and the rigid block mainly lies in that the position block is only a steady-state system, and the rigid block is a dynamic system. The force-moment block is a module system with input and output of force or moment, and the input and output of the module system are in a steady static relation. The position block and the force-moment block are divided from the rigid body block and the elastic constraint block, and are extensions of the rigid body block and the elastic constraint block concept. In practical systems, the configuration block and the force-moment block are often connected in series. In an actual automobile system, a plurality of automobile assemblies and component modules only have steady-state kinematic or static functions between the rigid block and the elastic constraint block, and the assemblies and the components do not influence the isolation of the model but do not belong to the types of the elastic constraint block and the rigid block. The modeling of other elements is realized through the position block and the force-moment block, and the modular modeling of all assemblies and parts in the model is realized. The invention provides the concepts of an elastic constraint block, a rigid block, a position block and a force-moment block, wherein the four modules form a basic dynamics functional module of a complex automobile model, and an automobile real-time dynamics model modeling method is established on the basis. The boundary of the established layered modular model module has clear definition, and can be convenient for real objects of different levels to replace corresponding modules in the model, so that the real object in-loop simulation of various levels of the automobile is realized, the requirement of simulation accuracy is met, and the problem that a real-time accurate simulation method for the automobile power condition is lacked in actual production is solved.
In a preferred embodiment of the present invention, as shown in fig. 2, the elastic restraint block is a module that provides force or moment action with the configuration of the adjacent module as an input. As shown in fig. 3, the elastic constraining block itself may be a complex dynamic system, but the rigid body blocks adjacent to it can only be input configuration, output force or torque. According to the interface definition of the elastic constraint block module, different rigid bodies are isolated and decoupled through the elastic constraint block, and a constraint equation (algebraic equation) cannot be generated.
In this embodiment, a calculation process of the elastic constraining block force is described by taking a most typical linear spring damping system as an example. As shown in FIG. 4, erIs an inertial system, the elastic constraint block B is between the rigid body A1And A2E is1And e2Is a body base on a rigid body. Assuming that the current time is t, freezing the rigid body A at the time1And A2The relative motion vector can be expressed as:
the first derivative of equation (1) is calculated to obtain the relative motion velocity between rigid bodies as:
in the formula, FsIs an elastic force matrix; K. c is spring rate array and damping array, R0Is a matrix of the initial lengths of the wire springs.
The calculation method of the elastic constraint block is not limited to the above example. According to the interface definition of the system module, as long as the modules meeting the elastic constraint block interface definition are all elastic constraint block types.
As shown in fig. 5, the rigid body block is a module that outputs a configuration by inputting a force or a moment of an adjacent elastic restraint block or force-moment block module or an external force or a moment. The external force or torque is the system external input, such as air resistance.
When each rigid body block in the system is isolated by the elastic constraint block, each rigid body is taken as the center, the acting force of the elastic constraint block and the force-moment block module which are connected with the rigid body block at the periphery is added, and dynamic equations are written in a row and column mode independently, so that the isolation and decoupling of the system are completed, and the established equations are ordinary differential equations.
And (4) freezing the current simulation time t, knowing the acting force of the rigid body, and calculating to obtain a derivative term of the motion state of the rigid body according to a rigid body dynamic equation.
According to the newton-euler equation of dynamics, the equation of dynamics of a rigid body can be expressed as:
wherein m is the mass of the rigid body; j is the moment of inertia of the rigid body;
a coordinate array of the absolute acceleration of the rigid body centroid on the body base;
∑ F, which is the coordinate array of absolute angular acceleration of rigid body on the basis of bodys、∑Ms∑ F as rigid body receiving force and moment from adjacent elastic constraint blocksk、∑Mk∑ F, which is a rigid body subjected to resultant force and resultant moment from adjacent force-moment block modulest、∑MtThe resultant force and resultant moment from the external input of the model are applied to the rigid body.
In this embodiment, as shown in fig. 6, the bit pattern block is a system module whose input and output are bit patterns, and the input and output of the interface are in a steady-state kinematic relationship. The bit-block differs from the rigid-block primarily in that the bit-block is only a steady-state system, whereas the rigid-block is a dynamic system. As shown in fig. 7, the force-torque block is a module system in which the input and output are both force or torque, and the input and output are in a steady-state static relationship. The position block and the force-moment block are divided from the rigid body block and the elastic constraint block, and are extensions of the rigid body block and the elastic constraint block concept. In practical systems, the configuration block and the force-moment block are often connected in series.
One specific embodiment of the invention is a method for constructing a steering system modular dynamics model, comprising the following steps:
s1, acquiring the mechanical part characteristics of each element in the steering system;
s2, generating an elastic restraint block if the mechanical part characteristic of the steering column is elastic, wherein the elastic restraint block takes the angular displacement of a steering wheel of a driver as input and outputs steering column torque to the Ackerman steering mechanism and the steering assistance;
s3, generating a force-torque block if the steering power-assisted mechanism part is static, wherein the force-torque block takes the steering column torque of the steering column as input and outputs power assistance to the Ackerman steering mechanism;
and S4, when the mechanical characteristics of the Ackerman steering mechanism are rigid body characteristics, generating a rigid body block which outputs a steering angle profile to the suspension with the column torque of the steering column and the assist force of the steering assist as inputs.
The embodiment specifically introduces a simulation method of a steering system in an automobile system, which completes modular modeling of a power system by acquiring the mechanism characteristics of each element in the steering system and generating different modules according to the mechanism characteristics of the elements.
Further, the ackermann steering mechanism generates a rigid block when the mechanical member characteristic is a rigid body characteristic, and outputs a steering angle configuration to a suspension with a column torque of the steering column and an assist force of a steering assist as inputs, and specifically includes:
acquiring the mechanism part characteristics of each element in the Ackerman steering mechanism;
generating a rigid block when the mechanical part characteristic of the steering gear is rigid body characteristic, wherein the rigid block takes the steering column torque of the steering column and the power assistance of the steering power assistance as input and outputs the motion state configuration to the steering transmission mechanism;
if the mechanical part of the steering transmission mechanism has elastic characteristics, an elastic constraint block is generated, and the elastic constraint block takes the motion state configuration of the steering gear as input and outputs torque to a steering wheel;
when the mechanical member characteristic of the steerable wheels is a rigid body characteristic, a rigid body block is generated which outputs the angular position to the suspension with the torque of the steering transmission mechanism as an input.
In the present embodiment, the ackermann steering mechanism having a multi-stage structure is further divided, and the ackermann steering mechanism outputs a motion state due to input of a moment, and is a rigid body block type as a whole. However, the ackermann steering mechanism further comprises a next-stage element, wherein the steering gear and the steering wheel are next-stage rigid blocks, the steering transmission mechanism is a next-stage elastic constraint block, the steering transmission mechanism is positioned in front of the steering gear and the steering wheel, a hierarchical modular model established for the automobile is realized while the isolation and decoupling of the system are realized, and the problem of inaccurate simulation caused by the fact that the current real-time dynamics commercial software is only modularized at a system level and is difficult to close model modules corresponding to different-level real objects as required is solved.
As shown in fig. 8, in the present embodiment, the steering system model includes a steering column, a steering assist, and an ackermann steering mechanism. The driver steering wheel is used for angular displacement input, and is isolated and decoupled from the Ackerman steering mechanism through a steering column module (an elastic constraint block). The ackermann steering mechanism is a rigid block module and comprises a rigid block (a steering gear and a steering wheel) and an elastic constraint block (a steering transmission mechanism) at the next level. The steering power assistance is a connecting module between a steering column and an Ackerman steering mechanism, and belongs to the type of a force-moment block. Because the force-moment block is divided from the elastic constraint block and is an extension of the concept of the elastic constraint block, the model equation of the steering column and the steering assistance is as follows:
in the formula (I), the compound is shown in the specification,swis the steering wheel angle;sinputting a shaft angle for the steering gear; kcol、CcolRespectively steering column torsional stiffness and damping; mcolIs the steering column torque; mpsIs a steady state steering assist value; mpTo take account of the force-assisting value after hysteresissIs a time lag constant. The equation is based on rigid body kinematics, and the specific extrapolation method can be based on equations (1) - (3).
The boundary of the ackermann steering mechanism is the input torque and the output motion state, and belongs to the rigid body block type. The interior of the steering mechanism comprises a rigid block (a steering gear, left and right steering wheels) and an elastic restraint block (a steering transmission mechanism) of a next component stage.
The dynamic equation of the steering gear input shaft is as follows:
in the formula (I), the compound is shown in the specification,sinputting a shaft angle for the steering gear; i issEquivalent rotational inertia of an input shaft of the steering gear; csDamping the steering gear input shaft; mpThe steering assisting moment; i.e. isIs the product of the reverse force transmission ratio of the steering transmission mechanism and the steering gear; mlA moment about the kingpin is generated for the steering gear. Equation (9) is based on rigid body dynamics equations, and the specific extrapolation method is based on equation (5).
The function of the steering transmission mechanism module is to calculate the acting moment through the position and belongs to an elastic constraint block. The calculation of the equivalent deformation of the steering transmission mechanism is shown in equations (10) and (11). The equivalent moment of the tie rod about the kingpin is shown in equation (12).
In the formula,. DELTA.sl、ΔsrEquivalent deformation of the tie rod around the kingpin;spl、sprthe turning angles of the left wheel and the right wheel around the main pin are respectively;othe output end position of the steering gear is formed; i.e. il、irThe transmission ratios of the left transverse pull rod and the right transverse pull rod are respectively; kl、KrThe rigidity of the left and right tie rods around the main pin, Cl、CrRespectively a left and a right tie rodDamping of the kingpin. Equations (10) to (12) function to calculate the torque of the steering transmission mechanism, and the specific resulting method is based on equations (1) to (3).
The steering wheel is of the rigid block type and functions to calculate the rotation angle of the left and right steering wheels around the kingpin. According to the torque of the steering transmission mechanism, the centering torque around the main pin generated by the tire and the dry friction torque, the tabulated rotation dynamic equation of the steering wheel around the main pin is as follows:
in the formula (I), the compound is shown in the specification,spturning a steering wheel around a main pin; i isspIs the equivalent moment of inertia of the steering wheel around the axis of the kingpin; cspDamping the steering wheel around the kingpin; mlThe steering transmission mechanism is equivalent to the moment around the main pin; mfIs the steering dry friction torque; mzTo return the moment about the kingpin, ikThe steering ratio of the steering transmission mechanism.
The boundary between the steering system and the outside dynamics system is the suspension. The steering system outputs to the suspension the angle of rotation and angular velocity about the kingpin, and the suspension outputs the aligning moment about the kingpin to the steering system.
As shown in fig. 9, a specific embodiment of the present invention is that the block diagram is a modeling overall framework of a mechanical dynamics model, and is an expanded description of a complete vehicle dynamics model, and a construction method thereof is briefly described as follows: according to the characteristics of the mechanical component, selecting an elastic characteristic element as an elastic constraint block as an isolation unit between rigid bodies; selecting rigid body elements as rigid body blocks, wherein elastic constraint blocks are required to be isolated between the rigid body blocks, so that a constraint equation is not generated; parts not serving as rigid blocks and elastic restraint blocks are classified as positioning blocks or force-moment blocks according to the kinematic or static characteristics of the parts. The calculation equations of the modules can be obtained by referring to the foregoing embodiments, and are not described herein.
Further, the automobile real-time dynamics modular modeling method further comprises the step of constructing an electric control unit model through a sensing model, a strategy model and an actuator model according to the functional characteristics.
Because the current intelligent automobile motion control commands, such as steering wheel angle, braking deceleration and the like, all realize the control of the transverse and longitudinal motion of the automobile by sending control commands to the execution electric control units such as Electric Power Steering (EPS), an electronic stability control program (ESP), an electric vehicle central controller (VCU)/a fuel vehicle Engine Management System (EMS) and the like. However, most of the existing commercial real-time dynamics software lacks an execution electronic control unit model of an intelligent driving controller such as an Electric Power Steering (EPS) and an Electronic Stability Program (ESP), and it is difficult to effectively respond to an instruction of the intelligent driving control unit and simulate behavior characteristics of the execution electronic control unit. Meanwhile, in verification of an intelligent driving motion control algorithm, hardware-in-loop simulation needs to be performed on systems, assemblies and components which are difficult to model of an automobile part, most of current real-time dynamics commercial software such as CarSim, veDYNA and the like is modularized only at a system level, and model modules corresponding to different levels of real objects are difficult to close as required, so that the models are used for hardware-in-loop simulation of each level of the automobile.
As shown in fig. 10 and 11, in a preferred embodiment of the present invention, a modeling method of an electronic control unit model in an automobile dynamics model is provided, and an execution electronic control unit such as an Electric Power Steering (EPS), an electronic stability control program (ESP), a central control unit (VCU)/an Engine Management System (EMS) of an electric vehicle is composed of a sensor model, a strategy model, and an actuator model. The intelligent automobile motion control-oriented automobile real-time dynamics modular modeling framework and method comprises an automobile dynamics model and a motion control execution electronic control unit model. The intelligent driving motion control electric control execution unit model provides a sensor model, a strategy model and an actuator model, and solves the problem that the existing automobile dynamics model lacks an electric control unit model. In this embodiment, the intelligent driving motion control electric control execution unit model mainly includes a sensor model, a strategy model and an actuator model. In sensor modeling, gaussian noise is added to simulate noise in an actual sensor based on model values. In the strategy model, a control strategy is elaborately and accurately modeled and needs to include a key function model of a real vehicle-mounted computer (ECU). And constructing a model in the actuator model according to the function.
Further, the transfer function of the actuator model is
In the formula, K is the gain between the control quantity and the electric control signal, and tau is the dynamic response time of the actuating mechanism.
In a preferred embodiment of the invention, a transfer function of the actuator model is given. In practical engineering, actuators of electric control units such as an Electric Power Steering (EPS) and an electronic stability control program (ESP) are difficult to accurately model in real time. In the electric control unit model, the actuator model adopts a simplified function model. Considering the dynamic response time of the actuator in the actual process, the transfer function of the actuator model is
The problem of actuator modeling of executing electric control units such as an Electric Power Steering (EPS) and an electronic stability control program (ESP) is solved.
The embodiment of the invention also provides a modular modeling device for real-time dynamics of an automobile, which can realize all the processes of the modular modeling method for real-time dynamics of the automobile described in any embodiment, and the functions and the realized technical effects of each module and unit in the device are respectively the same as the functions and the realized technical effects of the driver driving type identification method described in the embodiment, and are not repeated herein.
As shown in fig. 12, an embodiment of the present invention further provides a modular modeling apparatus for real-time dynamics of an automobile, including:
the mechanism characteristic acquisition unit is used for acquiring the mechanism part characteristics of each element in the system to be processed;
the elastic constraint block generating unit is used for generating an elastic constraint block for an element with the elastic characteristic as the characteristic of the mechanism part, and the elastic constraint block takes the position form of the adjacent module as input and outputs force or moment;
a rigid body block generation unit for generating a rigid body block, which outputs a shape of a site with a force or a moment of an adjoining module or an external connection as an input, for an element whose mechanical member characteristic is a rigid body characteristic, the rigid body block being isolated from each other by elastic restraint blocks;
a bit pattern block generation unit for generating a bit pattern block for an element whose mechanical part characteristic is a kinematic property, the bit pattern block having bit patterns of adjoining modules as an input and outputting the bit pattern;
and the force-moment block generating unit is used for generating a force-moment block for an element with the static property of the mechanism part, and the force-moment block takes the force or the moment of the adjacent module or the external module as input and outputs the force or the moment.
Further, the modular modeling device for real-time dynamics of the automobile further comprises: and the electric control module generating unit is used for constructing an electric control unit model through the sensing model, the strategy model and the actuator model according to the functional characteristics. Further, the transfer function of the actuator model is
In the formula, K is the gain between the control quantity and the electric control signal, and tau is the dynamic response time of the actuating mechanism.
As shown in fig. 13, an embodiment of the present invention further provides a terminal device, which includes a processor 10, a memory 20, and a computer program stored in the memory 20 and configured to be executed by the processor 10, where the processor 10, when executing the computer program, implements the modular modeling method for real-time dynamics of an automobile according to any one of the foregoing embodiments.
Preferably, the computer program can be divided into one or more modules/units (e.g. computer program 1, computer program 2,) which are stored in the memory 20 and executed by the processor 10 to accomplish the present invention. The one or more modules/units may be a series of computer program instruction segments capable of performing specific functions, which are used for describing the execution process of the computer program in the terminal device.
In summary, the embodiment of the invention provides a method, a device and a storage medium for modularized modeling of real-time dynamics of an automobile, which adopt an elastic constraint block to isolate and decouple a complex complete automobile dynamics system into a series of dynamics subsystem modules. "isolated" means that the complex mechanical vehicle dynamics model is isolated into individual sub-modules; "decoupled" means that each sub-module can be solved independently. The isolation decoupling of the whole vehicle dynamic system is realized through the elastic constraint block and the rigid body block, the generation of algebraic differential equations is effectively avoided, the established models are ordinary differential equations, and the requirement of simulation instantaneity is met. The modeling of the assembly and the component which only play the role of steady-state kinematics or statics in an actual automobile system and do not influence the isolation of the model but do not belong to the types of elastic constraint blocks and rigid body blocks is realized through the position block and the force-moment block. The basic dynamic function module of the complex automobile model is formed by four types of modules, the boundary of the established layered modular model module has definite definition, corresponding modules in the model can be conveniently replaced by real objects of different levels, real object in-loop simulation of various levels of the automobile is realized, and the requirement on simulation accuracy is met. The invention solves the problem that the current automobile dynamics simulation model can not accurately realize the verification of the intelligent driving motion control algorithm in real time, and provides a method for accurately simulating the automobile power condition in real time.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.
Claims (8)
1. A modular modeling method for real-time dynamics of an automobile is characterized by comprising the following steps:
acquiring the characteristics of mechanical parts of each element in a system to be processed;
if the mechanical part characteristic of the element is elastic, an elastic constraint block is generated, and the elastic constraint block takes the position form of the adjacent module as input and outputs force or torque;
generating a rigid block by taking the force or moment of the adjacent module or external connection as input and outputting the shape if the mechanical property of the element is rigid body property, wherein the rigid body blocks are isolated by elastic restraint blocks;
generating a position block if the mechanical part characteristic of the element is kinematic property, wherein the position block takes the position form of the adjacent module as input and outputs the position form;
the mechanical component properties of the element are static, which then generates a force-torque block that takes as input a force or torque of the adjoining module or of the external connection and outputs the force or torque.
2. The modular modeling method for real-time dynamics of automobiles according to claim 1, further comprising constructing an electronic control unit model through a sensing model, a strategy model and an actuator model according to functional characteristics.
3. The modular modeling method for automotive real-time dynamics as claimed in claim 2, wherein said actuator model has a transfer function of
In the formula, K is the gain between the control quantity and the electric control signal, and tau is the dynamic response time of the actuating mechanism.
4. An automotive real-time dynamics modular modeling apparatus, comprising:
the mechanism characteristic acquisition unit is used for acquiring the mechanism part characteristics of each element in the system to be processed;
the elastic constraint block generating unit is used for generating an elastic constraint block for an element with the elastic characteristic as the characteristic of the mechanism part, and the elastic constraint block takes the position form of the adjacent module as input and outputs force or moment;
a rigid body block generation unit for generating a rigid body block, which outputs a shape of a site with a force or a moment of an adjoining module or an external connection as an input, for an element whose mechanical member characteristic is a rigid body characteristic, the rigid body block being isolated from each other by elastic restraint blocks;
a bit pattern block generation unit for generating a bit pattern block for an element whose mechanical part characteristic is a kinematic property, the bit pattern block having bit patterns of adjoining modules as an input and outputting the bit pattern;
and the force-moment block generating unit is used for generating a force-moment block for an element with the static property of the mechanism part, and the force-moment block takes the force or the moment of the adjacent module or the external module as input and outputs the force or the moment.
5. The modular modeling apparatus of real-time dynamics for automotive vehicles according to claim 4, further comprising: and the electric control module generating unit is used for constructing an electric control unit model through the sensing model, the strategy model and the actuator model according to the functional characteristics.
6. A modular modeling method for real-time dynamics of an automobile is characterized by comprising the following steps:
acquiring the mechanical part characteristics of each element in the steering system;
generating an elastic restraint block if the mechanical part characteristic of the steering column is elastic, wherein the elastic restraint block takes the angular displacement of a steering wheel of a driver as input and outputs steering column torque to the Ackerman steering mechanism and the steering assistance;
the steering power-assisted mechanism is characterized in that a force-moment block is generated if the static property is adopted, and the force-moment block takes the steering column moment of a steering column as input and outputs power assistance to the Ackerman steering mechanism;
when the mechanical characteristics of the ackermann steering mechanism are rigid characteristics, a rigid block is generated which outputs a steering angle profile to the suspension with the column torque of the steering column and the assist force of the steering assist as inputs.
7. The modular modeling method for real-time dynamics of automobile of claim 6, wherein the rigid body block is generated when the mechanical member characteristics of the ackermann steering mechanism are rigid body characteristics, and the steering column torque and the power assistance of the steering column are used as input to output the rotation angle configuration to the suspension, specifically comprising:
acquiring the mechanism part characteristics of each element in the Ackerman steering mechanism;
generating a rigid block when the mechanical part characteristic of the steering gear is rigid body characteristic, wherein the rigid block takes the steering column torque of the steering column and the power assistance of the steering power assistance as input and outputs the motion state configuration to the steering transmission mechanism;
if the mechanical part of the steering transmission mechanism has elastic characteristics, an elastic constraint block is generated, and the elastic constraint block takes the motion state configuration of the steering gear as input and outputs torque to a steering wheel;
when the mechanical member characteristic of the steerable wheels is a rigid body characteristic, a rigid body block is generated which outputs the angular position to the suspension with the torque of the steering transmission mechanism as an input.
8. A computer-readable storage medium, characterized in that the computer-readable storage medium comprises a stored computer program; wherein the computer program controls a device in which the computer readable storage medium is located to execute the modular modeling method for real-time dynamics of automobile according to any one of claims 1-3, 6 and 7 when running.
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