A cab semi-active suspension control method based on pitch vibration control for commercial vehicle

Abstract

The present application relates to the field of automotive technology, in particular to a semi-active suspension control method for a commercial vehicle cab based on pitch vibration control, which utilizes the adjustable damping performance of a continuously variable damping shock absorber, utilizes a pitch motion controller and a vertical motion controller, calculates corresponding weight coefficients according to vehicle state information, combines pitch control and vertical control, obtains the final damping force of each suspension, combines a fuzzy control method, considers the influence of vehicle load on damping effect, introduces a load coefficient, takes the product of the control current calculated by the general fuzzy controller and the load coefficient as the final control current of the shock absorber, controls the damping coefficient of the shock absorber, thereby providing the isolation capability and anti-pitch capability of the suspension, and further, the present application can continuously adjust the control current through a cyclic adjustment process, so that the cab comfort is significantly improved compared with the traditional fuzzy control method.

Description

Technical Field

[0001] This invention relates to the field of automotive technology, and specifically to a semi-active suspension control method for a commercial vehicle cab based on pitch vibration control. Background Technology

[0002] With the continuous development of the automotive industry, commercial vehicles are no longer just transportation tools; people are also placing higher demands on their comfort. As shock absorber technology has advanced, magnetorheological (MRC) shock absorbers and continuously damped adjustable damping (CDC) shock absorbers have been developed and put into practical use.

[0003] Research on semi-active suspension systems currently focuses primarily on theoretical studies of quarter-vehicles, with limited application scenarios and few proposed solutions. In particular, there are few semi-active suspension products for commercial vehicle cabs. Many control methods in these systems exist only in theory, require numerous parameters, involve large computational loads, and place high demands on control system chips. In practice, these methods are difficult to implement, and there is a lack of cab suspension control solutions with strong execution capabilities. Summary of the Invention

[0004] The purpose of this invention is to provide a semi-active suspension control method for commercial vehicle cabs based on pitch vibration control, which improves the vibration isolation and anti-pitch capabilities of the suspension, thereby enhancing the comfort of commercial vehicles.

[0005] To achieve the above objectives, the present invention provides a semi-active suspension control method for commercial vehicle cabs based on pitch vibration control, comprising the following steps:

[0006] Step 1: Using continuously variable damping shock absorbers as suspension, construct a half-vehicle dynamics model for a commercial vehicle;

[0007] Step 2: Install one acceleration sensor at each of the upper and lower ends of each suspension mount in the cab to acquire acceleration signals, which will be used as input for the hybrid control system;

[0008] Step 3: Install distance measuring sensors at the chassis mounting points to obtain the mounting compression, calculate the vehicle load weight, and obtain the corresponding vehicle load factor. ;

[0009] Step 4: Calculate the corresponding sprung speed and unsprung speed using an accelerometer and an integrator circuit;

[0010] Step 5: Calculate the relative speed of the suspension using the sprung speed and the unsprung speed;

[0011] Step 6: Perform pitch and vertical motion control separately;

[0012] Step 7: Introduce a fuzzy control rule table to obtain the different weight coefficients of the two controllers for pitch motion control and vertical motion control;

[0013] Step 8: Calculate the control current of the vibration damper based on the comprehensive data;

[0014] Step 9: Based on the current magnitude calculated in Step 8, control the output current of the amplifier circuit to control the damping coefficient of the vibration damper, and then proceed to the next loop to execute Step 3.

[0015] Optionally, the commercial vehicle half-vehicle dynamics model includes a cab suspension and an excitation signal. The excitation signal serves as a simulated road surface information input. The cab suspension is composed of a continuously variable damping shock absorber and an air spring. The commercial vehicle half-vehicle dynamics model is in a stationary state when the hybrid control system is activated.

[0016] Optionally, the hybrid control system utilizes a pitch motion controller and a vertical motion controller to calculate corresponding weighting coefficients based on vehicle state information, thereby combining pitch control with vertical control to obtain the final damping force for each suspension.

[0017] Optionally, the input variables of the hybrid control system are the sprung speed and suspension relative speed obtained from the unsprung and sprung acceleration sensors and the integral circuit, and the output variable is the magnitude of the damping control current of the shock absorber.

[0018] Optionally, a vehicle load factor can be introduced based on different load capacities. Different fuzzification processes are applied to compare the control current calculated by a general fuzzy controller with the vehicle load factor. The product of these two values ​​serves as the control current for the final damper.

[0019] Optionally, the pitch control rules are improved based on classic ceiling control, and the improved formula is shown below:

[0020]

[0021]

[0022] in, This represents the damping coefficient of the left front suspension. The damping coefficient for the left rear suspension. The maximum damping coefficient, The minimum damping coefficient, For pitch acceleration, The pitch angle acceleration threshold, It represents the pitch angular velocity.

[0023] Optionally, the vertical control rule utilizes an improved single-sensor control strategy, designed to avoid errors present in the actual integration process and to achieve optimization across the entire frequency domain.

[0024] Optionally, in the fuzzy control rule of step 7, the input variable is the sprung mass acceleration. and sprung mass pitch acceleration The output variables are the weighting factors of each control strategy. .

[0025] This invention provides a semi-active suspension control method for commercial vehicle cabs based on pitch vibration control. Utilizing the adjustable damping performance of a continuously variable damping shock absorber, and employing pitch and vertical motion controllers, corresponding weighting coefficients are calculated based on vehicle state information. This combines pitch and vertical control to obtain the final damping force for each suspension. By incorporating fuzzy control and considering the impact of vehicle load on vibration reduction, a load coefficient is introduced. The product of the control current calculated by the general fuzzy controller and the load coefficient is used as the final control current of the shock absorber, thereby controlling the damping coefficient and providing vibration isolation and anti-pitch capabilities for the suspension. Furthermore, this invention can continuously adjust the control current through a cyclic adjustment process, significantly improving cab comfort compared to traditional fuzzy control methods. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a flowchart illustrating the steps of a semi-active suspension control method for a commercial vehicle cab based on pitch vibration control, according to the present invention.

[0028] Figure 2 This is a schematic diagram of the half-vehicle dynamics model structure of the vehicle of the present invention.

[0029] Figure 3 This is a schematic diagram of the basic structure of the hybrid control system of the vehicle of the present invention.

[0030] Figure 4 This is a schematic diagram of the vertical control rule flow of the present invention.

[0031] Figure 5 This is a schematic diagram of the damping characteristics of the vibration damper of the present invention. Detailed Implementation

[0032] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0033] Please see Figure 1 This invention provides a semi-active suspension control method for a commercial vehicle cab based on pitch vibration control, comprising the following steps:

[0034] S1: Using continuously variable damping shock absorbers as suspension, a half-vehicle dynamics model of a commercial vehicle is constructed;

[0035] S2: An acceleration sensor is installed at each of the upper and lower ends of each suspension in the cab to obtain acceleration signals, which are used as inputs for the hybrid control system;

[0036] S3: Install distance measuring sensors at the chassis mounts to obtain the mount compression, calculate the vehicle load weight, and obtain the corresponding vehicle load factor. ;

[0037] S4: The corresponding sprung speed and unsprung speed are calculated using an accelerometer and an integrator circuit;

[0038] S5: Calculate the relative speed of the suspension using the sprung speed and the unsprung speed;

[0039] S6: Perform pitch control and vertical control respectively;

[0040] S7: Introduce a fuzzy control rule table to obtain the different weight coefficients of the two controllers for pitch motion control and vertical motion control;

[0041] S8: Calculate the control current of the vibration damper based on comprehensive data;

[0042] S9: Based on the current magnitude calculated in step S8, control the output current of the amplifier circuit to control the damping coefficient of the vibration damper, and then proceed to the next cycle to execute step S3.

[0043] The following provides further explanation with reference to specific terminology and implementation steps:

[0044] 1) Commercial vehicle half-vehicle dynamics model

[0045] Half-car model Figure 2 As shown, a dynamic analysis was performed on it, and the following dynamic model was obtained:

[0046]

[0047]

[0048]

[0049] In the formula, For the sprung mass; The unsprung mass of the front suspension; The mass under the rear suspension spring; This is the stiffness coefficient of the damper spring; This is the tire's stiffness coefficient; This refers to the damping force output by the adjustable front suspension damper. The damping force output by the adjustable rear suspension damper is used to replace the damping force of the semi-active suspension in the model. , , These represent the sprung mass, unsprung mass, and vertical displacement of the road surface, respectively. The moment of inertia of pitching about the center of mass; This is the distance from the front mount point to the center of gravity of the vehicle body; This is the distance from the rear suspension point to the vehicle's center of gravity.

[0050] 2) Load factor

[0051] The load of a commercial vehicle affects the vibration damping effect of the chassis, thus altering the frequency and amplitude of vibrations beneath the cab suspension. To achieve better vibration damping, different fuzzification processes are needed depending on the load. Since there is only one output variable—current—a load factor is introduced here. This new parameter uses the product of the control current calculated by a general fuzzy controller and the load factor as the final control current of the vibration damper. Load factor Determined by formula (1), where This refers to the vehicle's load capacity.

[0052] (1)

[0053] 3) Basic Structure of Hybrid Control

[0054] Using pitch and vertical motion controllers, corresponding weighting coefficients are calculated based on vehicle state information, combining pitch and vertical control to obtain the final damping force for each suspension mount. The input variables for this hybrid control are the sprung speed and relative speed of the suspension mounts, obtained from unsprung and sprung acceleration sensors and an integrator circuit. The output variable is the magnitude of the damper's damping control current. The basic structure is as follows: Figure 3 As shown.

[0055] 4) Pitch control rules

[0056] When the cab pitches and rolls due to frame displacement, the shock absorbers require low damping during compression and high damping during extension to reduce the change in cab angular displacement. Therefore, when the vehicle body pitches, the damping of the front and rear shock absorbers is changed to generate a counter-restoring torque to suppress the vehicle body's movement.

[0057] The concept of roof control involves installing a roof damper between the vehicle body and an imaginary "roof." This damper serves only to dissipate energy, and when the damping coefficient reaches a certain value, it can achieve a certain vibration reduction effect. The pitch control rule is an improvement upon the classic roof control method. The improved formula is shown below:

[0058]

[0059]

[0060] in, This represents the damping coefficient of the left front suspension. The damping coefficient for the left rear suspension. The maximum damping coefficient, The minimum damping coefficient, For pitch acceleration, The pitch angle acceleration threshold, It represents the pitch angular velocity.

[0061] 5) Vertical control rules

[0062] An improved single-sensor control strategy is employed to avoid errors present in the actual integration process and achieve optimization across the entire frequency domain. The improved single-sensor control strategy avoids the integration stage in the original algorithm by using an IIR digital filter to filter different frequencies of the sprung mass acceleration signal. Furthermore, the switching-type single-sensor control strategy is improved into a continuous-type control strategy. The control strategy flowchart is shown below. Figure 4 As shown.

[0063] 6 Fuzzy Control Rules

[0064] By using pitch and vertical motion controllers, the corresponding weighting coefficients are calculated based on vehicle state information, so that pitch control and vertical control are combined to obtain the final damping force of each suspension.

[0065] 1. There are two input variables: the acceleration of the spring mass. and sprung mass pitch acceleration The error quantity and error change rate input to the fuzzy controller are taken from 5 language values, namely positive large (PB), positive small (PS), zero (ZO), negative small (NS), and negative large (NB).

[0066] 2. There are two output variables, which are the weighting factors for each control strategy. The fuzzy controller outputs four linguistic values: positive large (B), positive small (BM), negative small (SM), and negative large (S).

[0067] 3. The fuzzy control rule table is shown in Table 1 below.

[0068] Table 1 Fuzzy Control Rules

[0069]

[0070] (a) Vertical control weighting factor

[0071]

[0072] (b) Pitch control weighting factor

[0073] 7) Based on the above rules, the variable damping force of each shock absorber is derived and distributed to each suspension shock absorber. This is done in order to... Figure 3 The mapping relationship of the vertical control rule flow is used as a reference. Figure 5 This is a schematic diagram of the damping characteristics of the vibration damper of the present invention.

[0074] Furthermore, this invention utilizes the above control method to establish a semi-vehicle dynamics model in simulation software, combining dynamic principles. Using parameters of a certain type of commercial vehicle as dynamics model parameters and random road surface data as road surface input for the model, simulations are performed using the semi-active suspension and the original vehicle passive suspension of the above control method, and the following results are obtained through comparison.

[0075] On random road surfaces, compared with the original passive suspension, the semi-active suspension with control methods reduced the MTVV value by 8.3%. Vibration was improved, and the comfort of the cab was further enhanced.

[0076] The above description discloses only one preferred embodiment of the present invention, and should not be construed as limiting the scope of the present invention. Those skilled in the art will understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A semi-active suspension control method for a commercial vehicle cab based on pitch vibration control, characterized in that, Includes the following steps: Step 1: Using continuously variable damping shock absorbers as suspension, construct a half-vehicle dynamics model for a commercial vehicle; Step 2: Install one acceleration sensor at each of the upper and lower ends of each suspension mount in the cab to acquire acceleration signals, which will be used as input for the hybrid control system; Step 3: Install distance measuring sensors at the chassis mounting points to obtain the mounting compression, calculate the vehicle load weight, and obtain the corresponding vehicle load factor. ; Step 4: Calculate the corresponding sprung speed and unsprung speed using an accelerometer and an integrator circuit; Step 5: Calculate the relative speed of the suspension using the sprung speed and the unsprung speed; Step 6: Perform pitch and vertical motion control separately; The pitch control rule is an improvement on the classic ceiling control, and the improved formula is shown below: in, This represents the damping coefficient of the left front suspension. The damping coefficient for the left rear suspension. The maximum damping coefficient, The minimum damping coefficient, For pitch acceleration, The pitch angle acceleration threshold, The pitch angular velocity, , These represent the vertical displacements of the sprung mass and the unsprung mass, respectively. The vertical control rule utilizes an improved single-sensor control strategy to avoid errors present in the actual integration process and achieve optimization effects across the entire frequency domain. Step 7: Introduce a fuzzy control rule table to obtain the different weight coefficients of the two controllers for pitch motion control and vertical motion control; In the fuzzy control rule of step 7, the input variable is the sprung mass acceleration. and sprung mass pitch acceleration The output variables are the weighting factors of each control strategy. ; Weighting factor Obtained dynamically through a fuzzy control rule table; Step 8: Calculate the control current of the vibration damper based on the comprehensive data; Step 9: Based on the current magnitude calculated in Step 8, control the output current of the amplifier circuit to control the damping coefficient of the vibration damper, and then proceed to the next loop to execute Step 3.

2. The semi-active suspension control method for commercial vehicle cabs based on pitch vibration control as described in claim 1, characterized in that, The commercial vehicle half-vehicle dynamics model includes a cab suspension and an excitation signal. The excitation signal serves as a simulated road surface information input. The cab suspension is composed of a continuously variable damping shock absorber and an air spring. The commercial vehicle half-vehicle dynamics model is in a stationary state when the hybrid control system is activated.

3. The semi-active suspension control method for commercial vehicle cabs based on pitch vibration control as described in claim 2, characterized in that, The hybrid control system utilizes pitch motion controllers and vertical motion controllers to calculate corresponding weighting coefficients based on vehicle state information, thereby combining pitch control with vertical control to obtain the final damping force for each suspension.

4. The semi-active suspension control method for commercial vehicle cabs based on pitch vibration control as described in claim 3, characterized in that, The input variables of the hybrid control system are the sprung speed and suspension relative speed obtained from the unsprung and sprung acceleration sensors and the integral circuit, and the output variable is the magnitude of the damping control current of the shock absorber.

5. The semi-active suspension control method for commercial vehicle cabs based on pitch vibration control as described in claim 4, characterized in that, The vehicle load factor is introduced based on different load capacities. Different fuzzification processes are applied to compare the control current calculated by a general fuzzy controller with the vehicle load factor. The product of these two values ​​serves as the control current for the final damper.

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