A modeling method for a fully floating cab of a commercial vehicle

Abstract

The present invention discloses a commercial vehicle full-floating cab modeling method, which consists of a cab motion module, a motion influence module on ride, a cab ride module, and a ride influence module on motion; the cab motion module refers to solving the longitudinal, lateral, and yaw motions of the cab according to the longitudinal, lateral, and yaw motions of the whole vehicle; the motion influence module on ride estimates the boundary force of the frame on the cab suspension according to the longitudinal, lateral, and yaw motions of the cab, and then uses the RC / PC theory and the two-force bar hypothesis; the method is convenient and accurate, and the cab suspension is modeled based on the test curve obtained by the K&C test. The modeling process is convenient, the computing power requirement is not high, and the simulation results are accurate. The architecture of the method is systematic and comprehensive, taking into account a variety of situations including flexible deformation, and has a wide range of applications, and other similar mechanisms can be modeled with similar ideas.

Description

Technical Field

[0001] The invention relates to the technical field of vehicle dynamics modeling and simulation, in particular to a modeling method for a full-floating cab of a commercial vehicle. Background Art

[0002] With the continuous development of commercial vehicle technology, consumers have higher and higher requirements for the sports performance of commercial vehicles, especially the comfort requirements. In commercial vehicles with full-floating / semi-floating cabs, the vibration of the vehicle is first transmitted to the driver through the suspension system and then through the cab suspension system. Effective modeling of the cab can more accurately simulate the movement of the driver's environment and more realistically simulate the driver's body feeling, thereby providing an important basis for subsequent vehicle suspension adjustment, active control and other strategies, so as to improve the vehicle's ride comfort.

[0003] At present, there are two main types of cab modeling methods. One is the modeling method based on multi-body dynamics represented by Adams, and the other is the modeling method based on vehicle characteristics represented by TruckSim. For the cab suspension, it has vertical load-bearing characteristics and guiding characteristics. The suspension links arranged at different lengths and angles determine the variation law of the suspension kinematics (K characteristics), and the elastic deformation of the rubber bushings and rods determines the variation law of the suspension elastic kinematics (C characteristics). Due to the complex arrangement of the suspension guiding mechanism and the difficulty in measuring the rubber functional components, it is difficult to directly use the multi-body dynamics software Adams to model and simulate in real time based on the structure, and due to the differences in suspension between different vehicles, the applicability and inclusiveness of the model is poor. The K&C experimental measurement method is often used in current automotive engineering. The semi-empirical model is used to describe the K and C characteristics of the suspension, and the vehicle is modeled based on the characteristics. TruckSim is a software that models vehicle characteristics. However, when modeling the cab, it does not consider the complete K&C characteristics. Instead, it simulates the roll and pitch motions of the cab based on multi-body dynamics by giving the positions of the roll axis and pitch axis. It does not consider the changes in the roll center and pitch center of the cab, the flexibility of the cab, the dry friction characteristics of the spring, etc.

[0004] In view of the above situation, the present invention is based on the roll center, pitch center theory and the "two-force bar" hypothesis (ignoring the mass and degree of freedom of the suspension guide rod, and only considering its kinematic constraints and static force transmission), and the longitudinal boundary force and lateral boundary force of the frame on the cab suspension are equivalent to anti-roll force and anti-pitch force, which are instantly transmitted to the cab body, so as to more accurately solve the vertical, roll and pitch motion of the cab. The present invention is also based on the semi-empirical model of K&C experimental measurement, solves the kinematic correction of the cab suspension, and estimates the kinematic correction of the cab according to the kinematic correction fitting of the suspension point, and obtains the final longitudinal and lateral positions of the cab. Summary of the invention

[0005] The object of the present invention is to provide a commercial vehicle full-floating cab modeling method to solve the problems raised in the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A commercial vehicle full-floating cab modeling method is composed of a cab motion module, a motion-to-ride module, a cab ride motion module, and a ride-to-motion module.

[0008] The cab Motion module solves the longitudinal, lateral and yaw motions of the cab based on the longitudinal, lateral and yaw motions of the whole vehicle; the Motion influence on Ride module estimates the boundary force of the frame on the cab suspension based on the longitudinal, lateral and yaw motions of the cab, and then solves the anti-roll and anti-pitch forces of the cab through RC / PC theory and two-force bar assumption; the cab Ride motion module solves the vertical, roll and pitch motions of the cab based on the spring damping force, anti-roll force, anti-pitch force and other forces (such as air force, gravity, etc.) acted on the cab; the Ride influence on Motion module is based on the K&C position correction of the cab suspension point, fits the K&C position correction of the cab, and solves the final longitudinal, lateral and yaw positions of the cab.

[0009] Compared with the prior art, the present invention has the following beneficial effects:

[0010] 1. This method is convenient and accurate. It performs characteristic-based modeling of the cab suspension based on the test curve obtained from the K&C test. The modeling process is convenient, the computing power requirement is not high, and the simulation results are accurate.

[0011] 2. The architecture of this method is comprehensive, taking into account a variety of situations including flexible deformation, and has a wide range of applications. Other similar mechanisms (such as powertrains and their suspensions, shock-absorbing seats and their suspensions, etc.) can be modeled with similar ideas. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The invention discloses a commercial vehicle full-floating cab modeling method.

[0013] Figure 2 It is a schematic diagram of the boundary force transmitted from the vehicle frame to the cab suspension according to the present invention.

[0014] Figure 3 It is a schematic diagram of the transmission of force by the two-force rod of the non-independent suspension roll of a passenger vehicle according to the present invention.

[0015] Figure 4It is a schematic diagram of the force transmission of the two-force rod of the cab suspension described in the present invention. DETAILED DESCRIPTION

[0016] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0017] Embodiment 1:

[0018] Please refer to Figure 1 A commercial vehicle full-floating cab modeling method consists of a cab motion module (I), a motion-to-ride module (II), a cab ride motion module (III), and a ride-to-motion module (IV). The schematic diagram is shown in Figure 1 shown.

[0019] Step 1: The cab motion module (I) is to solve the longitudinal, lateral and yaw motions of the cab according to the longitudinal, lateral and yaw motions of the whole vehicle;

[0020] Step 2: The module (II) of the influence of Motion on Ride estimates the boundary force of the frame on the cab suspension according to the longitudinal, lateral and yaw motions of the cab, and then solves the anti-roll force and anti-pitch force of the cab through the RC / PC theory and the two-force bar assumption;

[0021] Step 3: The cab Ride motion module (III) is to solve the vertical, roll and pitch motion of the cab according to the spring damping force, anti-roll force, anti-pitch force and other forces (such as air force, gravity, etc.) on the cab;

[0022] Step 4, the module (IV) on the influence of Ride on Motion is based on the K&C position correction of the cab suspension point, which fits the K&C position correction of the cab and solves the final longitudinal, lateral and yaw positions of the cab.

[0023] Embodiment 2, based on Embodiment 1, the working principle of the cab Motion module (I) is: the stiffness of each component of the commercial vehicle (including the unsprung part, the frame part, the cab part, etc.) in the longitudinal, lateral and yaw directions is much higher than that in the vertical, roll and pitch directions, and the movement amplitude of each component of the commercial vehicle in the longitudinal, lateral and yaw directions is also much higher than that in the vertical, roll and pitch directions. If the solution is based on the spatial multi-body dynamics, it is easy to generate a rigid equation. Therefore, the vehicle is regarded as a whole in the longitudinal, lateral and yaw directions, and the longitudinal, lateral and yaw movements of each component of the vehicle "fixed" on the whole vehicle are obtained through the longitudinal, lateral and yaw movements of the whole vehicle. For the cab, based on the position of the origin of the cab coordinate system in the whole vehicle coordinate system, kinematics is used to solve the longitudinal motion, lateral motion and yaw motion of the cab.

[0024] Example 3, based on Example 1, the influence module (II) of Motion on Ride is composed of three parts: inertia force / torque (2.1), RC / PC guiding characteristics (2.2) and anti-roll / pitch force (2.3). Inertia force / torque (2.1) means that based on the acceleration of the longitudinal movement, lateral movement and yaw movement of the cab, according to Newton's law or D'Alembert's principle, the static equilibrium equation of inertia force and resultant external force is listed to solve the boundary force of the cab. The schematic diagram of the boundary force of the cab suspension imposed by the frame is shown as follows: Figure 2 As shown. The RC / PC guidance characteristic (2.2) means that, similar to Figure 3 The roll center theory and "two-force bar" assumption of the non-independent suspension of a passenger car shown in the figure simplifies the boundary force of the frame on the cab suspension to Figure 4 The frame shown transmits forces to the cab through four points (RC_Front, RC_Rear, PC_Left, PC_Right). The lifting force provided by the suspension guide mechanism to the cab is not considered here, and it is assumed that the vertical force on the cab is borne by the vertical spring damping. In the case where the forces at the four points in the longitudinal, lateral and yaw directions of the cab are insufficient to solve the problem, it can be assumed that the cab is symmetrical on the left and right, so the longitudinal forces transmitted by the left and right pitch centers are always equal, or it can be assumed that the yaw moment is provided by the average of the four forces based on the geometric position. Anti-roll / pitch force (2.3) refers to solving the anti-roll moment and anti-pitch moment of the cab based on the positions of the four points relative to the origin of the cab coordinate system (front roll center height, rear roll center height, left pitch center height, right pitch center height) and the magnitude of the forces transmitted at the four points. In addition, it should also be based on the following Figure 2 Based on the geometric position shown, solve the internal force of the frame on the suspension mechanism.

[0025] Example 4, based on Example 1, the cab Ride motion module (III) consists of two parts: suspension vertical spring damping force (3.1) and cab vertical, roll, and pitch motion (3.2). The suspension vertical spring damping force (3.1) refers to the establishment of a Fancher model (Fancher can express dry friction characteristics) based on the wheel center suspension stiffness curve measured in the previous K&C test, and a damping model based on the previous shock absorber characteristic test. According to the relative position and relative motion between the cab and the frame, the suspension vertical spring damping force exerted on the cab is solved. The cab vertical, roll, and pitch motion (3.2) consists of two parts: rigid body motion (3.2.1) and flexible body motion (3.2.2). Rigid body motion (3.2.1) refers to solving the low-frequency rigid body motion of the cab based on the anti-roll moment, anti-pitch moment, suspension vertical spring damping force, air force, gravity, etc.; flexible body motion (3.2.2) refers to solving the small-scale high-frequency flexible deformation of the cab near the large-scale rigid body motion equilibrium position based on the magnitude and position of the force acting on the cab, using the modal superposition method. The final vertical, roll, and pitch motions (3.2) of the cab are solved by linear superposition of rigid body motion (3.2.1) and flexible body motion (3.2.2). It should be noted that since the cab is subject to less vibration excitation forces in the longitudinal and lateral directions, the flexible deformation of the cab only needs to consider the vertical direction.

[0026] Example 5, based on Example 1, the Ride influence module on Motion (IV) is composed of three parts: the vertical motion of the suspension point (4.1), the K&C correction of the suspension point (4.2) and the K&C correction of the cab (4.3). The vertical motion of the suspension point (4.1) refers to solving the vertical position of the suspension point based on the vertical, roll, pitch motion of the cab and the position of the suspension point in the cab coordinate system. The K&C correction of the suspension point (4.2) refers to solving the horizontal position correction of the suspension point based on the characteristics such as the wheel center lateral displacement curve and the wheel center longitudinal displacement curve measured in the K&C test, according to the vertical position and force of the suspension point in the cab coordinate system. The K&C correction of the cab (4.3) refers to solving the horizontal position correction at the origin of the cab coordinate system based on the position correction of multiple suspension points using the least squares fitting method, and superimposing it on the result of the cab Motion motion module (I) in step 1 to obtain the final longitudinal, lateral and yaw positions of the cab.

[0027] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above and that the invention can be implemented in other specific forms without departing from the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0028] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A commercial vehicle full-floating cab modeling method, characterized in that: The system is implemented by a cab motion module, a motion-to-ride module, a cab ride module, and a ride-to-motion module. The system specifically includes the following steps: Step 1: The cab motion module solves the longitudinal, lateral and yaw motions of the cab according to the longitudinal, lateral and yaw motions of the vehicle; Step 2: The module of Motion's influence on Ride solves the anti-roll force and anti-pitch force on the cab; Step 3: The cab Ride motion module solves the vertical, roll and pitch motion of the cab; Step 4: The module of Ride’s influence on Motion solves the final longitudinal, lateral and yaw positions of the cab; The cab Ride motion module is composed of two parts: suspension vertical spring damping force and cab vertical, roll and pitch motion. The Ride influence module is composed of three parts: suspension point vertical motion, suspension point K&C correction and cab K&C correction. The Motion influence module is composed of three parts: inertia force / torque, RC / PC guiding characteristics and anti-roll / pitch force. Inertia force / torque refers to the acceleration based on the longitudinal, lateral and yaw motions of the cab. RC / PC steering characteristics refer to the use of the roll center theory and two-force bar assumption of the non-independent suspension of passenger cars to simplify the boundary force of the frame to the cab suspension into the force transmitted from the frame to the cab through four points. The four points are RC_Front, RC_Rear, PC_Left, and PC_Right. Anti-roll / pitch force refers to solving the anti-roll moment and anti-pitch moment of the cab based on the positions of the four points relative to the origin of the cab coordinate system and the magnitude of the forces transmitted at the four points. The vertical spring damping force of the suspension refers to the Fancher model established based on the wheel center suspension stiffness curve measured in the previous K&C test, and the damping model established based on the previous shock absorber characteristic test. According to the relative position and relative movement between the cab and the frame, the vertical spring damping force of the suspension on the cab is solved. The vertical, roll and pitching motions of the cab are composed of two parts: rigid body motion and flexible body motion. Rigid body motion refers to the low-frequency rigid body motion of the cab based on the anti-roll moment, anti-pitch moment, vertical spring damping force of the suspension, air force and gravity. Flexible body motion refers to the small-scale high-frequency flexible deformation of the cab near the large-scale rigid body motion equilibrium position based on the magnitude and position of the force on the cab, using the modal superposition method. The final vertical, roll and pitching motions of the cab are solved by the linear superposition of rigid body motion and flexible body motion. The vertical motion of the suspension point refers to solving the vertical position of the suspension point based on the vertical, roll and pitch motions of the cab and the position of the suspension point in the cab coordinate system. The K&C correction of the suspension point refers to solving the horizontal position correction of the suspension point based on the characteristics of the wheel center lateral displacement curve and the wheel center longitudinal displacement curve measured in the K&C test and the vertical position and force of the suspension point in the cab coordinate system. The K&C correction of the cab refers to solving the horizontal position correction at the origin of the cab coordinate system based on the position correction of multiple suspension points using the least squares fitting method, and superimposing it on the result of the cab Motion module in step 1 to obtain the final longitudinal, lateral and yaw positions of the cab.

2. A commercial vehicle full-floating cab modeling method according to claim 1, characterized in that: In step 1, for the cab, based on the position of the origin of the cab coordinate system in the vehicle coordinate system, kinematics is used to solve the longitudinal motion, lateral motion and yaw motion of the cab.

3. A commercial vehicle full-floating cab modeling method according to claim 2, characterized in that: Specifically, the step 2 includes: the influence module of Motion on Ride estimates the boundary force of the frame on the cab suspension according to the longitudinal, lateral and yaw motions of the cab, and then solves the anti-roll force and anti-pitch force of the cab through RC / PC theory and two-force bar assumption.

4. A commercial vehicle full-floating cab modeling method according to claim 3, characterized in that: The step 3 is specifically as follows: the cab Ride motion module solves the vertical, roll and pitch motions of the cab according to the spring damping force, anti-roll force and anti-pitch force exerted on the cab.

5. A commercial vehicle full-floating cab modeling method according to claim 4, characterized in that: Specifically, the step 4 includes: the Ride influence on Motion module fits the K&C position correction of the cab based on the K&C position correction of the cab suspension point, and solves the final longitudinal, lateral and yaw positions of the cab.

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