Coupling control commercial vehicle cab semi-active suspension control method

Abstract

The invention relates to the technical field of automobile control, in particular to a coupling-controlled commercial vehicle cab semi-active suspension control method, which is used for carrying out coupling control of perpendicularity, pitching and side inclination on a commercial vehicle cab semi-active suspension system under the condition of considering the damping characteristic of a CDC shock absorber. The CDC shock absorber is treated as a black box model, and multi-gear damping control is carried out, so that construction of a complex parameter identification model is avoided, and the real vehicle system calculation amount is reduced; a classic ceiling damping control strategy is adopted to solve the problem of nonlinearity of each-gear damping curve of the CDC shock absorber; and a coupling control strategy is adopted, and ceiling suppression force is arranged, so that the vibration isolation performance in other directions is prevented from being deteriorated due to optimization of single perpendicularity, pitching and side inclination. Therefore, the problem that an existing commercial vehicle cab suspension system cannot completely achieve continuous damping control is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile control, and in particular to a coupling-controlled semi-active suspension control method for a commercial vehicle cab. Background Art

[0002] With the growing trend toward electrification, commercial truck cab suspension systems are evolving from passive to semi-active systems aimed at improving ride performance. Previous research on semi-active suspension systems has primarily focused on improving the ride performance of individual suspension nodes based on a quarter-vehicle model, with limited consideration given to the inter-coupling interactions between these nodes. A semi-active cab suspension system is a complex dynamic system encompassing vertical, pitch, and roll vibrations. Therefore, research on control strategies for this system should address these three vibrations.

[0003] Currently, there's no comprehensive inverter model for the CDC (Continuous Damping Control) shock absorbers used in commercial vehicle cab suspension systems. Consequently, continuous damping control cannot be fully implemented in most cases, and instead is treated as a black-box model with varying nonlinear damping characteristics at varying current outputs. This experimentally measured black-box model is relatively accurate and should be considered when designing semi-active cab suspension control strategies. Summary of the Invention

[0004] The object of the present invention is to provide a coupled-controlled commercial vehicle cab semi-active suspension control method, aiming to solve the problem that the existing commercial vehicle cab suspension system cannot fully achieve continuous damping control.

[0005] To achieve the above object, the present invention provides a method for controlling a commercial vehicle cab semi-active suspension with coupled control, comprising the following steps:

[0006] The signal sensing system obtains the acceleration and displacement signals of the corresponding points;

[0007] The signal preprocessing system converts the acquired signal into the required speed signal and relative speed signal;

[0008] The cab attitude predictor converts the speed signal into a cab speed attitude signal;

[0009] The attitude suppressor converts the speed attitude signal into a skyhook suppression force signal;

[0010] The relative velocity signal is converted into the estimated basic damping force signal of the four suspension systems by the basic damping predictor;

[0011] The damping force decoupling controller converts the ceiling suppression force signal and the estimated base damping force signal into the ideal damping output force signals of the four suspension systems.

[0012] The ideal damping output force signal and the relative velocity signal are converted into a current signal by the damping force inverter, which acts on the continuously variable damping (CDC) shock absorber.

[0013] Among them, in "obtaining acceleration and displacement signals of corresponding points by the signal sensing system", the signal sensing system includes 3 acceleration sensors and 4 wire displacement sensors, which are used to obtain acceleration and displacement signals of corresponding points in the cab.

[0014] Among them, in "the signal preprocessing system converts the acquired signal into the required velocity signal and relative velocity signal", the signal preprocessing system converts the acceleration signal into the velocity signal and converts the displacement signal into the relative velocity signal through discrete acquisition, trend removal, integration operation and differentiation operation.

[0015] Among them, in “the cab attitude predictor converts the speed signal into a cab speed attitude signal”, the speed attitude signal includes vertical, pitch and roll speeds.

[0016] The process of “converting the ideal damping output force signal and the relative velocity signal into a current signal by a damping force inverter and applying the current signal to a continuously variable damping (CDC) shock absorber” includes the following steps:

[0017] Calculate the damping force signals that the four suspension systems should output at each current level based on the input relative speed signals;

[0018] A digital signal for determining actual output current according to an input ideal damping output force signal;

[0019] The actual output current signal is converted from a digital signal to an analog signal and input to the CDC at the corresponding end for vibration reduction.

[0020] The present invention provides a coupled control method for a semi-active cab suspension of a commercial vehicle, comprising the following steps: a signal sensing system acquires acceleration and displacement signals of corresponding points; a signal preprocessing system converts the acquired signals into desired velocity signals and relative velocity signals; a cab attitude predictor converts the velocity signals into cab velocity attitude signals; an attitude suppressor converts the velocity attitude signals into skyhook damping force signals; a base damping predictor converts the relative velocity signals into estimated base damping force signals for four suspension systems; a damping force decoupling controller converts the skyhook damping force signals and the estimated base damping force signals into ideal damping output force signals for the four suspension systems; and a damping force inverter converts the ideal damping output force signals and the relative velocity signals into current signals, which act on continuously variable damping (CDC) shock absorbers. The present invention performs coupled control of the vertical, pitch, and roll characteristics of the semi-active cab suspension system of a commercial vehicle, taking into account the damping characteristics of the CDC shock absorbers. The CDC shock absorber is treated as a black box model, implementing multi-stage damping control to avoid building complex parameter identification models and reduce the computational complexity of the actual vehicle system. A classic skyhook damping control strategy is employed to address the nonlinearity of the CDC shock absorber's damping curve at each stage. A coupled control strategy is employed to allocate skyhook damping forces, preventing the optimization of a single vertical, pitch, or roll position from degrading vibration isolation performance in other directions. This addresses the existing commercial vehicle cab suspension system's inability to fully implement continuous damping control. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 This is a flow chart of a commercial vehicle cab semi-active suspension control method with coupled control provided by the present invention.

[0023] Figure 2 This is a schematic diagram of the layout of 7 sensors.

[0024] Figure 3 It is a schematic diagram for determining the positive directions of cab pitch and roll according to the right-hand screw rule.

[0025] Figure 4 It is the damping characteristic curve.

[0026] Figure 5 It is a correlation diagram between the input force signal and the output force signal.

[0027] Figure 6is the damping force signal Fc base 、Fc I1 、Fc I2 、Fc I3 、Fc I4 、Fc I5 、Fc I6 Graph of the curve.

[0028] Figure 7 The flow chart of the damping force inverter converting the ideal damping output force signal and the relative velocity signal into a current signal, which acts on the continuously variable damping (CDC) shock absorber. DETAILED DESCRIPTION

[0029] The following describes embodiments of the present invention in detail, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and are not to be construed as limiting the present invention.

[0030] See also Figures 1 to 7 The present invention provides a method for controlling a semi-active suspension of a commercial vehicle cab with coupling control, comprising the following steps:

[0031] S1 obtains the acceleration and displacement signals of the corresponding points through the signal sensing system;

[0032] The signal sensing system comprises three acceleration sensors and four wire displacement sensors, and is used to obtain acceleration and displacement signals of corresponding points in the cab.

[0033] Specifically, the signal sensing system of the present invention is composed of 3 acceleration sensors and 4 wire displacement sensors. The layout of these 7 sensors is as follows: Figure 2 As shown in the figure, three acceleration sensors are installed at the passive ends of the left front, left rear, and right rear suspension systems of the cab; four cable displacement sensors are installed at both ends of the four suspension systems. The signal sensing system obtains the vertical acceleration signals of the passive ends of the left front, left rear, and right rear suspension systems of the cab through the three acceleration sensors. The relative displacement signals Z of the four suspension systems (front left, front right, rear left, and rear right) are obtained by using the wire displacement sensor. c_def_lf 、Z c_def_rf 、Z c_def_lr 、Z c_def_rr These 7 signals are output as voltage signals.

[0034] S2 converts the acquired signal into the required speed signal and relative speed signal by the signal preprocessing system;

[0035] The signal preprocessing system converts the acceleration signal into a velocity signal and converts the displacement signal into a relative velocity signal through discrete acquisition, trend removal, integration operation and differentiation operation.

[0036] Specifically, first, the voltage signal generated in step S1 is discretized and collected as an analog signal, and stored in the vehicle-mounted ECU system.

[0037] Secondly, the trend items of the 7 collected signals are removed respectively, and the formula is:

[0038]

[0039] Where: z [k] is the sampling point at the current moment; N is the number of sampling points; It is the estimated sampling value retained after removing interference.

[0040] 2.3 Then, for the 3-way acceleration signal The vertical velocity signals of the passive ends of the left front, left rear and right rear suspension systems of the cab are obtained by performing integration operation through Runge-Kutta method. The formula for the integration operation of the Runge-Kutta method is:

[0041]

[0042] Where: k(i) is the iterative acceleration assignment; y(i) is the iterative velocity assignment; For acceleration The velocity value obtained by integration; h is the discrete integration step, which is related to the sampling time.

[0043] Finally, for the 4-way displacement signal Z c_def_lf 、Z c_def_rf 、Z c_def_lr 、Z c_def_rr , by performing differential operation using the forward difference method, the relative speed signals of the four suspension systems, namely, the left front, right front, left rear, and right rear, are obtained. The backward difference calculation formula used is:

[0044]

[0045] Among them, x j 、x j-1 is the displacement between the iteration point and the previous point; is the velocity value obtained by differentiating the displacement; h is the discrete differential step, which is related to the sampling time.

[0046] S3 converts the speed signal into the speed attitude signal of the cab by the cab attitude estimator;

[0047] The velocity attitude signal includes vertical, pitch and roll velocity.

[0048] Specifically, the cab attitude predictor involved in the present invention works in an explicit manner. Therefore, it is necessary to model the cab offline in advance to confirm the explicit calculation formula. The cab modeling is shown in the figure below. The cab is regarded as a rigid body, with the center of mass of the cab as the coordinate origin, the forward direction of the vehicle is the positive direction of the x-axis, the left is the positive direction of the y-axis, and the upward direction is the positive direction of the z-axis. The positive direction of the cab pitch and roll is determined according to the right-hand screw rule, as shown in the figure below. Figure 3 As shown in β and α.

[0049] Figure 2 middle, is the roll, pitch and vertical speed of the cab; (X c_lf ,Y c_lf )、(X c_lr ,Y c_lf )、(X c_rr ,Y c_rr )for The x-axis and y-axis coordinates in the cab coordinate system.

[0050] according to Figure 3 The correlation relationship in can be determined that the cab attitude predictor involved in the present invention solves the cab speed attitude information by the following formula:

[0051]

[0052] Where inv is the solution function of the inverse matrix. In the commercial vehicle cab suspension system involved in the present invention,

[0053]

[0054] S4 converts the speed attitude signal into a skyhook suppression force signal by the attitude suppressor;

[0055] Specifically, the attitude suppressor involved in the present invention calculates the skyhook suppression force signal by the following formula:

[0056]

[0057] Among them, C z_sky 、C β_sky 、C α_sky is the vertical, pitch and roll skyhook damping coefficient; F z 、M β 、M α It is the vertical motion suppression force signal and the pitch and roll motion suppression torque signal.

[0058] The ceiling damping suppression coefficient in the attitude suppressor of the present invention is a variable related to the vehicle speed, that is, it satisfies the following formula:

[0059]

[0060] Among them, f z (v), f β (v), f α (v) The three functions are nonlinear and can be tuned using the following two methods:

[0061] Option 1: Calibrate through real-vehicle testing. This calibration process requires testing the vehicle on a secondary cement road, secondary asphalt road, and speed bumps at different speeds.

[0062] Option 2: By building a 12-degree-of-freedom full-vehicle dynamics model in Simulink, the model is calibrated using Class A, Class B, Class C, and Class D random road excitations and speed bump conditions at different vehicle speeds.

[0063] S5 converts the relative velocity signal into the estimated basic damping force signal of the four suspension systems by the basic damping predictor;

[0064] Specifically, in the basic damping predictor involved in the present invention, the basic damping characteristic curve of the CDC shock absorber is recorded in an explicit manner. This damping characteristic curve is the optimal damping characteristic curve calibrated under various complex working conditions for the cab suspension system and is the initial passive damping of the original vehicle. This curve function is as follows: Figure 4 shown.

[0065] The base damping estimator calculates the estimated base damping forces for the four suspension systems using the following formula:

[0066]

[0067] Among them, the function Fc base (v def )like Figure 4 As shown; is the estimated basic damping force.

[0068] S6 uses the damping force decoupling controller to convert the skylight suppression force signal and the estimated base damping force signal into the ideal damping output force signals of the four suspension systems;

[0069] Specifically, the damping force decoupling controller involved in the present invention also works in a display manner. Similar to the attitude controller involved in step S3, it is necessary to model the cab to determine the correlation between the input force signal and the output force signal. Figure 5 As shown, the cab is modeled in the same manner as in step S3. Figure 5 In (X c_lf ,Y c_lf )、(X c_lr ,Y c_lf )、(X c_rf ,Y c_rf )、(X c_rr ,Y c_rr ) are the passive end coordinates of the left front, left rear, right front and right rear suspension points; F z 、M β 、M α F is the vertical ceiling restraint, pitch and roll ceiling control moment; r_sky_lf 、F r_sky_lr 、F r_sky_rf 、F r_sky_rr is the decoupling force between the ceiling restraining force and the restraining moment at the four suspension points; is the estimated base damping force of the four mounts; The ideal damping output forces of the four mounts are given by Figure 5 The modeling situation in is determined.

[0070] according to Figure 5 According to the correlation in , it can be determined that the damping force decoupling controller involved in the present invention solves the ideal damping output force of the four suspensions according to the following formula:

[0071]

[0072] Wherein, pinv() is a pseudo-inverse matrix function. In the example involved in the present invention,

[0073]

[0074] The S7 uses a damping force inverter to convert the ideal damping output force signal and the relative velocity signal into a current signal, which acts on the continuously variable damping (CDC) shock absorber.

[0075] S71 calculates the damping force signals that can be output by the four suspension systems at each current level according to the input relative speed signals;

[0076] Specifically, based on the input relative speed signal, the damping force signal that can be output by the four suspension systems at each current level is calculated in an explicit manner. Take the left front suspension system as an example: Assume that the input relative speed signal at a certain moment is v def , the damping force inverter will firstly Figure 6 The CDC shock absorber black box model information shown is used to calculate the output damping force signal Fc base 、Fc I1 、Fc I2 、Fc I3 、FcI4 、Fc I5 、Fc I6 ;

[0077] S72 determines a digital signal of an actual output current according to the input ideal damping output force signal;

[0078] Specifically, based on the input ideal damping output force signal, the current signal corresponding to the damping force signal that can be output is determined, which is the digital signal of the actual output current. In this process, the actual output current is determined according to the following formula:

[0079]

[0080] Among them, I c_out is the digital signal of the actual output current; I1, I2, I3, I base , I4, I5, I6 are Fc I1 、Fc I2 、Fc I3 、Fc base 、Fc I4 、Fc I5 、Fc I6 The corresponding current value.

[0081] S73 converts the actual output current signal from a digital signal to an analog signal and inputs it into the CDC vibration reduction at the corresponding end.

[0082] Specifically, the actual output current signal is converted from a digital signal to an analog signal and input into the CDC damper at the corresponding end.

[0083] To verify the effectiveness of the control strategy described in this paper, a full-vehicle dynamics model of the cab semi-active suspension system was constructed in Simulink. Considering the common operating conditions for commercial vehicles, which include secondary cement roads, secondary asphalt roads, and single speed bumps, Class A, B, C, and D random road surface excitations and a single speed bump with a height of 30 mm and a width of 500 m were used as the test surface. The verification speed was set at 50 km / h.

[0084] Using the original vehicle's passive (basic damping) damping as a comparison, simulation results were obtained, as shown in Table 1: Test results for the five aforementioned operating conditions. The results for Level A road excitation are shown in Table 1; those for Level B road excitation are shown in Table 2; those for Level C road excitation are shown in Table 3; those for Level D road excitation are shown in Table 4; and those for speed bump road excitation are shown in Table 5. It should be noted that the evaluation criteria for random road excitation tests are the RMS acceleration value; for speed bump road excitation tests, the evaluation criteria are the MTVV acceleration value.

[0085]

[0086] Table 1

[0087]

[0088] Table 2

[0089]

[0090] Table 3

[0091]

[0092]

[0093] Table 4

[0094]

[0095] Table 5

[0096] Beneficial effects

[0097] This invention can couple vertical, pitch, and roll control of a commercial vehicle cab semi-active suspension system while taking into account the damping characteristics of the CDC shock absorber. By treating the CDC shock absorber as a black box model and performing multi-level damping control, it avoids the need to construct complex parameter identification models and reduces the computational complexity of the actual vehicle system.

[0098] A classic skyhook damping control strategy is adopted to solve the nonlinear problem of the damping curve of each gear of the CDC shock absorber. A coupling control strategy is adopted to arrange the skyhook suppression force, so as to avoid the deterioration of vibration isolation performance in other directions due to the optimization of a single vertical, pitch, or roll direction.

[0099] The above disclosure is merely a preferred embodiment of a coupled-controlled commercial vehicle cab semi-active suspension control method of the present invention. This is certainly not intended to limit the scope of the present invention. A person skilled in the art will understand that implementing all or part of the processes of the above embodiment and making equivalent changes in accordance with the claims of the present invention still fall within the scope of the invention.

Claims

1. A method for controlling a semi-active suspension of a commercial vehicle cab with coupling control, characterized in that: The following steps are involved: The signal sensing system obtains the acceleration and displacement signals of the corresponding points; The signal preprocessing system converts the acquired signal into the required speed signal and relative speed signal; The cab attitude predictor converts the speed signal into a cab speed attitude signal; The attitude suppressor converts the speed attitude signal into a skyhook suppression force signal; The relative velocity signal is converted into the estimated basic damping force signal of the four suspension systems by the basic damping predictor; The damping force decoupling controller converts the ceiling suppression force signal and the estimated base damping force signal into the ideal damping output force signals of the four suspension systems. The ideal damping output force signal and the relative velocity signal are converted into a current signal by the damping force inverter, which acts on the continuously variable damping (CDC) shock absorber.

2. The commercial vehicle cab semi-active suspension control method of coupling control according to claim 1, characterized in that: In "Acquisition of acceleration and displacement signals of corresponding points by a signal sensing system", the signal sensing system includes three acceleration sensors and four wire displacement sensors, which are used to obtain acceleration and displacement signals of corresponding points in the cab.

3. The commercial vehicle cab semi-active suspension control method of coupling control according to claim 1, characterized in that: In "the signal preprocessing system converts the acquired signal into the desired velocity signal and relative velocity signal", the signal preprocessing system converts the acceleration signal into the velocity signal and the displacement signal into the relative velocity signal through discretized acquisition, trend removal, integration and differentiation operations.

4. The commercial vehicle cab semi-active suspension control method of coupling control according to claim 1, characterized in that: In “the cab attitude predictor converts the speed signal into a cab speed attitude signal”, the speed attitude signal includes vertical, pitch and roll speeds.

5. The commercial vehicle cab semi-active suspension control method of coupling control according to claim 4, characterized in that: In "converting the ideal damping output force signal and the relative velocity signal into a current signal by a damping force inverter and applying the current signal to a continuously variable damping (CDC) shock absorber", the following steps are included: Calculate the damping force signals that the four suspension systems should output at each current level based on the input relative speed signals; A digital signal for determining actual output current according to an input ideal damping output force signal; The actual output current signal is converted from a digital signal to an analog signal and input to the CDC at the corresponding end for vibration reduction.

Images