Suspension control method for carrying out coupling control on acceleration attitude of heavy truck cab

Abstract

The invention relates to the technical field of automobile engineering and control, in particular to a suspension control method for performing coupling control on the acceleration attitude of a heavy truck cab, which comprises the following steps of: firstly, acquiring an acceleration attitude signal of the cab by arranging an attitude sensing system in the cab; a suspension end attitude observation system is used for processing to obtain a suspension end relative speed signal, and a cab attitude suppression system is used for calculating an attitude suppression amount; the damping force distribution system calculates the output damping force of each suspension end, and finally the damping force inverter controls the continuous damping adjustable shock absorbers of the suspension ends, so that the decoupling operation process is relatively simple, and the computing power resource of a vehicle-mounted ECU system is saved. Through simulation verification, under the condition of not depending on accurate modeling of the heavy truck, coupling control over the vertical acceleration attitude, the pitching acceleration attitude and the roll acceleration attitude of the cab is achieved.

Description

Technical Field

[0001] The present invention relates to the field of automobile engineering and control technology, and in particular to a suspension control method for performing coupling control on the acceleration posture of a heavy truck cab. Background Art

[0002] Heavy trucks often travel on rough, bumpy roads, and road disturbances significantly impact the cab's acceleration profile. Cabin acceleration profile includes vertical acceleration profile, pitch acceleration profile, and roll acceleration profile. Past engineering experience shows that vertical acceleration profile and pitch acceleration are the primary factors influencing cab ride comfort.

[0003] The key to improving the ride performance of semi-active suspension systems lies in their control methods. Previous semi-active suspension control methods have limitations, making them difficult to apply in engineering applications: 1. Most semi-active suspension control methods are based on a quarter-vehicle model and only consider vertical acceleration and attitude suppression, lacking control over pitch and roll accelerations. 2. Some semi-active suspension control methods that can achieve coupled control of cab acceleration and attitude require precise modeling of heavy trucks and real-time computation of these models, which consumes significant computing resources. 3. Most semi-active suspension control methods suffer from poor robustness, as actual vehicle systems inevitably experience dynamic disturbances. These disturbances include changes in cab mass, center of mass, and moment of inertia caused by occupant changes, as well as noise in the acquired acceleration and attitude signals. Summary of the Invention

[0004] The purpose of the present invention is to provide a suspension control method for coupling control of the acceleration posture of a heavy truck cab, which realizes the coupling control of the vertical, pitch and roll acceleration posture of the cab without relying on accurate modeling of the heavy truck.

[0005] To achieve the above object, the present invention provides a suspension control method for coupling control of the acceleration posture of a heavy truck cab, comprising the following steps:

[0006] Step 1: The cab attitude sensing system obtains the cab acceleration attitude signal;

[0007] Step 2: Obtain the relative velocity signal of the mount end through the mount end state observation system;

[0008] Step 3: The cab attitude suppression system calculates the attitude suppression amount;

[0009] Step 4: Calculate the output damping force of each suspension end by the damping force distribution system;

[0010] Step 5: The damping force inverter controls the continuously damping adjustable shock absorber at each suspension end.

[0011] Optionally, in step 1, the acceleration signal is obtained by installing the vertical vibration acceleration sensor at the passive end of the left rear, right front and right rear suspension system of the cab, and then the vertical, roll angle and pitch angle acceleration signals of the cab are obtained through attitude decoupling calculation.

[0012] Optionally, in step 2, the relative displacement signals of the suspension ends are obtained by installing distance measuring sensors at the four suspension ends of the cab, and the relative speed signals of the left front, right front, left rear and right rear suspension ends of the cab are calculated.

[0013] Optionally, the cab attitude suppression system includes a three-layer structure of a vertical attitude suppressor, a pitch attitude suppressor and a roll attitude suppressor; each layer of attitude suppressor converts the cab acceleration attitude signal in the corresponding direction into an attitude suppression value signal in that direction by constructing a closed-loop control iterative operation structure composed of an expanded state observation module and a nonlinear error feedback module.

[0014] Optionally, the damping force distribution system includes two parts: a decoupling module and a limiting module; the decoupling module decouples the posture suppression signal into an output damping force distributed to each suspension end; the limiting module adjusts the output damping force distributed to the shock absorber at each suspension end so that it is within the output range of the shock absorber.

[0015] Optionally, the damping force distribution system includes two parts: a decoupling module and a limiting module; the decoupling module decouples the posture suppression signal into an output damping force distributed to each suspension end; the limiting module adjusts the output damping force distributed to the shock absorber at each suspension end so that it is within the output range of the shock absorber.

[0016] Optionally, in step 5, the damping force inverter explicitly decouples the actual damping force, and the expression is:

[0017]

[0018] Among them, I i is the actual input current of a certain suspension end shock absorber; f ci is the actual output damping force of the shock absorber at a certain suspension end; In order to interpolate the external load characteristic curve of the shock absorber damping force, a positive parameter needs to be adjusted; exp() is a natural exponential function.

[0019] This invention provides a suspension control method for coupled control of the acceleration attitude of a heavy-duty truck cab. First, a cab acceleration attitude signal is acquired by installing a posture sensing system in the cab. A suspension end attitude observation system then processes the signal to obtain the relative velocity of the suspension end. A cab attitude suppression system then calculates the attitude suppression amount. A damping force distribution system calculates the output damping force at each suspension end. Finally, a damping force inverter controls the continuously adjustable damper at each suspension end. The decoupling operation process is relatively simple, conserving computing power resources in the onboard ECU system. Simulations have demonstrated that this method achieves coupled control of the cab's vertical, pitch, and roll acceleration attitude without relying on precise modeling of heavy-duty trucks. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] 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.

[0021] Figure 1 It is a schematic flow chart of the steps of a suspension control method for coupling control of the acceleration posture of a heavy truck cab of the present invention.

[0022] Figure 2 It is a schematic diagram of the rigid body modeling structure of a cab of the present invention according to a suspension control method for coupling control of the acceleration posture of a heavy truck cab.

[0023] Figure 3 It is a schematic diagram of the damping force external load characteristic curve of the continuously damping adjustable shock absorber of the present invention.

[0024] Figure 4 It is a schematic diagram of the simulation structure of a whole vehicle model of a heavy truck according to a specific embodiment of the present invention.

[0025] Figure 5 It is a power spectrum density diagram of the vertical acceleration of the semi-active suspension system and the passive suspension system in the specific embodiment of the present invention.

[0026] Figure 6 It is a power spectrum density diagram of the cab pitch angle acceleration of the semi-active suspension system and the passive suspension system derived in a specific embodiment of the present invention.

[0027] Figure 7 It is a power spectrum density diagram of cab roll angle acceleration of the semi-active suspension system and the passive suspension system derived in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0028] 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.

[0029] See also Figure 1 The present invention provides a suspension control method for coupling control of the acceleration posture of a heavy truck cab, comprising the following steps:

[0030] Step 1: The cab attitude sensing system obtains the cab acceleration attitude signal;

[0031] Step 2: Obtain the relative velocity signal of the mount end through the mount end state observation system;

[0032] Step 3: The cab attitude suppression system calculates the attitude suppression amount;

[0033] Step 4: Calculate the output damping force of each suspension end by the damping force distribution system;

[0034] Step 5: The damping force inverter controls the continuously damping adjustable shock absorber at each suspension end.

[0035] The following is a further explanation based on the specific implementation steps:

[0036] 1. The cab attitude sensing system obtains the cab acceleration attitude signal:

[0037] The cab attitude sensing system of the present invention obtains the acceleration attitude signal of the cab through the following steps:

[0038] 1.1 First, vertical vibration acceleration sensors installed on the passive ends of the left rear, right front, and right rear cab suspension systems generate acceleration signals. The resulting voltage signals are amplified by a conditioning circuit and converted into digital signals for storage in the vehicle's ECU system.

[0039] 1.2 Then, the mean filter is used to remove the trend term offset error of the collected acceleration signal. The expression of acceleration mean filter is:

[0040]

[0041] Where a1(k) is the acceleration value after mean filtering, a0(k) is the acceleration value of the kth point collected by the acceleration sensor, and N is the number of sampling points.

[0042] 1.3 Finally, based on the collected acceleration signals, the cab attitude is decoupled to obtain the vertical, pitch, and roll accelerations of the cab. Before the decoupling operation, the cab needs to be modeled. Assuming that the cab is a rigid body, with the cab center of mass as the coordinate origin, the vehicle's forward direction as the positive x-axis, the left as the positive y-axis, and the upward direction as the positive z-axis, the positive directions of the pitch angle β and roll angle α are determined according to the right-hand rule, as follows: Figure 2 shown.

[0043] The attitude decoupling of the cab is calculated using the following formula:

[0044]

[0045] Where, is the vertical acceleration signal of the right front, left rear and right rear suspension passive ends after mean filtering; (p x2 ,p y2 ) refers to the horizontal plane coordinate of the right front sensor; (p x3 ,p y3 ) refers to the horizontal plane coordinate of the left rear sensor; (p x4 ,p y4 ) refers to the horizontal plane coordinate of the right rear sensor; It is the vertical acceleration, roll acceleration and pitch acceleration signal of the cab.

[0046] The cab vertical, roll and pitch acceleration signals are obtained through the cab attitude sensing system.

[0047] 2. Obtain the relative speed signal of the mount end from the mount end state observation system:

[0048] The suspension end state observation system of the present invention obtains the relative velocity signal of the suspension end according to the following steps:

[0049] 2.1 First, the relative displacement signals of the four suspension ends are obtained by using distance sensors installed at the four suspension ends of the cab. The obtained voltage signals are amplified by the conditioning circuit, converted into analog to digital, and then stored as digital signals in the vehicle ECU system.

[0050] 2.2 Then, the mean filter is used to remove the trend term offset error of the collected displacement signal, and its expression is:

[0051]

[0052] Where s1(k) is the displacement value after mean filtering, s0(k) is the displacement value of the kth point collected by the acceleration sensor, and N is the number of sampling points.

[0053] 2.3 Finally, the tracking differentiator performs progressive differential operation to obtain the relative velocity signal, which is expressed as:

[0054]

[0055] Where: s1(k) is the displacement signal after mean filtering; s2(k) is the iterative process variable, which is the follow-up signal of s1(k); h is the discrete integration step size during the integration operation, which is related to the operating frequency of the vehicle ECU system; r is the speed factor, and h0 is the filter factor, which together determine the accuracy of the speed signal obtained by the differential operation and are positive adjustment quantities; v2(k) is the speed signal obtained by the differential operation; fhan[s2(k),v2(k),s1(k),r,h0] is the fastest integrated function, and its expression is:

[0056]

[0057] Where: δ T ,δ T0 is a scalar, related to the value of the set value r,h0; y T ,b T0 ,b T It is the variable that tracks the iteration during the progressive operation of the differentiator; sign() is the sign function.

[0058] The relative speed signals of the left front, right front, left rear and right rear suspension ends of the cab are obtained through the above suspension end state observation system.

[0059] 3. The attitude suppression amount is calculated by the cab attitude suppression system:

[0060] The cab attitude suppression system of the present invention comprises a three-layer structure consisting of a vertical attitude suppressor, a pitch attitude suppressor, and a roll attitude suppressor. Each attitude suppressor layer converts the cab acceleration attitude signal in the corresponding direction into an attitude suppression signal in that direction by constructing a closed-loop control iterative operation structure composed of an extended state observation module (ESO) and a nonlinear error feedback module (NLSEF). This closed-loop control iterative operation structure draws on some principles of active disturbance rejection controllers. The ESO module estimates the dynamic disturbance and model uncertainty in the corresponding acceleration attitude direction, and compensates for this factor with the assistance of the nonlinear error feedback module. The effective acceleration suppression amount in the corresponding direction is extracted from the compensation amount as the attitude suppression amount, and a PD closed-loop control relationship is established between the acceleration attitude and the attitude suppression amount. This closed-loop control operation structure establishes a functional relationship between the acceleration value and the attitude suppression amount while avoiding the need for precise modeling of the heavy-duty truck vehicle model.

[0061] 3.1 The expression of the extended state observation module (ESO) of the vertical attitude inhibitor is:

[0062]

[0063] Where: a z (k) is the vertical acceleration value collected by the cab attitude perception system; l1(k) is the vertical acceleration observation value during the iteration process; e z (k) is the observation error of vertical acceleration during the iteration process; l2(k) is the differential observation of vertical acceleration during the iteration process; l3(k) is the total estimate of dynamic disturbance and model uncertainty in the vertical direction during the iteration process, which determines the observation accuracy and disturbance estimation effect; h is the discrete step length of the integration operation; ε lE1 ,ε lE2 ,δ lE ,ω l is a positive parameter that needs to be adjusted; fal(e,ε,δ) is a nonlinear function, and its expression is:

[0064]

[0065] The nonlinear error feedback module (NLSEF) of the vertical attitude suppressor is expressed as:

[0066]

[0067] Where: u l (k) is the amount of compensation for dynamic disturbances and model uncertainty in the vertical direction during the iteration process; u z (k) is the vertical attitude suppression amount separated from the compensation amount during the iteration process; ε lN1 ,ε lN2 ,δ lN It is a positive parameter that needs to be adjusted.

[0068] 3.2 The extended state observation module (ESO) expression of the pitch attitude suppressor is:

[0069]

[0070] Where: a β (k) is the pitch acceleration value collected by the cab attitude perception system; θ1(k) is the observed value of pitch acceleration during the iteration process; e θ (k) is the observation error of the pitch acceleration during the iteration process; θ2(k) is the differential observation of the pitch acceleration during the iteration process; θ3(k) is the total estimate of the dynamic disturbance and model uncertainty in the pitch direction during the iteration process; h is the discrete step size of the integration operation; ε θE1 ,ε θE2 ,δθE ,ω θ is a positive parameter that needs to be adjusted; fal(e,ε,δ) is a nonlinear function.

[0071] The nonlinear error feedback module (NLSEF) of the pitch attitude suppressor is expressed as:

[0072]

[0073] Where: u θ (k) is the amount of compensation for dynamic disturbances and model uncertainty in the pitch direction during the iteration process; u β (k) is the pitch attitude suppression amount separated from the compensation amount during the iteration process; ε θN1 ,ε θN2 ,δ θN It is a positive parameter that needs to be adjusted.

[0074] 3.3 The extended state observation module (ESO) of the roll attitude inhibitor is expressed as:

[0075]

[0076] Where: a α (k) is the roll acceleration value collected by the cab attitude sensing system; is the roll acceleration observed during the iteration process; is the observation error of the roll acceleration during the iteration process; is the differential observation of the roll acceleration during the iteration process; is the total estimate of the dynamic disturbance and model uncertainty in the roll direction during the iteration process; h is the discrete step length of the integration operation; is a positive parameter that needs to be adjusted; fal(e,ε,δ) is a nonlinear function.

[0077] The nonlinear error feedback module (NLSEF) of the roll attitude suppressor is expressed as:

[0078]

[0079] Where: is the amount used to compensate for the dynamic disturbance and model uncertainty in the roll direction during the iteration process; u α (k) is the roll attitude suppression amount separated from the compensation amount during the iteration process; It is a positive parameter that needs to be adjusted.

[0080] Through the above-mentioned cab attitude suppression system, the cab vertical, roll angle and pitch angle acceleration signals It is converted into the attitude suppression signal u in the corresponding directionz ,u α ,μ β .

[0081] 4. Calculate the output damping force of each suspension end using the damping force distribution system:

[0082] The damping force distribution system involved in the present invention comprises two parts: a decoupling module and a limiting module. The decoupling module decouples the attitude suppression signal into the output damping force distributed to each suspension end; the limiting module adjusts the output damping force distributed to the shock absorber at each suspension end to keep it within the shock absorber's output range.

[0083] 4.1 The expression of decoupling the attitude suppression amount by the decoupling module is:

[0084]

[0085] Where: u z ,u α ,μ β is the cab attitude suppression amount; μ z ,μ α ,μ β In order to suppress the amplification factor, for the heavy truck cab, the vibration in the vertical and pitch directions has a greater impact on the ride comfort, so the vertical and pitch amplification factor μ z ,μ β Generally, it is within the range of [1.5,3], and the roll coefficient μ α Take the range of [0.7,1] to ensure that it does not deteriorate; p y1 ,p y2 ,p y3 ,p y4 is the y-axis coordinate of the left front, right front, left rear and right rear suspension ends in the cab coordinate system; x1 ,p x2 ,p x3 ,p x4 are the x-axis coordinates of the left front, right front, left rear and right rear suspension ends in the cab coordinate system; The ideal damping force assigned to the left front, right front, left rear, and right rear shock absorbers; inv() is a pseudo-inverse matrix function.

[0086] 4.2 The expression used by the limiting module to adjust the damping force distributed to each suspension end shock absorber is:

[0087]

[0088] Where: is the relative velocity value of a certain suspension end; f cmax ,f cmin is the relative speed The maximum and minimum output damping forces of the lower shock absorber; is the ideal output damping force of a certain suspension end shock absorber; f ci is the actual output damping force of the shock absorber at a certain suspension end.

[0089] Through the above-mentioned cab attitude suppression system, the cab attitude suppression amount signal u z ,u α ,u β Relative velocity signal of each suspension end It is converted into the real resistance output damping force signal f of each suspension end shock absorber c1 ,f c2 ,f c3 ,f c4 .

[0090] 5. The damping force inverter controls the continuously damping adjustable shock absorber at each suspension end:

[0091] The continuously damping adjustable shock absorber of the present invention can adjust the damping force outputted by it in a relatively large range. The damping force external load characteristic curve thereof is as follows: Figure 3 shown.

[0092] In the case of the continuously adjustable damping shock absorber of the present invention, its output damping force is actually a function of the relative velocity of the mount end and the shock absorber input current. To conserve hardware storage space in the on-board ECU system, a set of calculation formulas is designed in the damping force inverter involved in the present invention to explicitly decouple the actual damping force. The expression is:

[0093]

[0094] Where: I i is the actual input current of a certain suspension end shock absorber; f ci is the actual output damping force of the shock absorber at a certain suspension end; In order to interpolate the external load characteristic curve of the shock absorber damping force, a positive parameter needs to be adjusted; exp() is a natural exponential function.

[0095] The actual input current signal I c1 ,I c2 ,I c3 ,I c4 , it also needs to be converted into the shock absorber at the corresponding end of the control current input through the digital-to-analog conversion module to complete a closed-loop control.

[0096] Furthermore, in order to more realistically verify the effectiveness of the control method of the present invention, a vehicle multi-body dynamics model is established in Adams based on the structural parameters of a heavy truck, such as Figure 4As shown. For the signals obtained from the sensor installation points in the Adams vehicle model, white noise interference and constant term bias interference are added in Simulink to simulate the actual signal acquisition situation. At the same time, a cab semi-active suspension model and a cab passive suspension model are built in Simulink, and the semi-active suspension model is controlled by the method mentioned in the present invention, and a joint simulation is performed with the vehicle model built by Adams. Since the secondary asphalt pavement on which heavy trucks travel in actual vehicle conditions is relatively close to the D-grade pavement, the D-grade pavement is selected as the random pavement excitation. The test vehicle speed is 40km / h.

[0097] The simulation results show that the RMS values of the cab's vertical acceleration and pitch acceleration decreased by 22.58% and 30.53%, respectively, and the RMS value of the roll acceleration decreased by 0.71%. This shows that the vertical and pitch acceleration postures of the cab are significantly optimized, while the roll acceleration posture shows no significant improvement or deterioration, which is consistent with the expected control effect.

[0098] Further analyze the optimization effect of each acceleration posture in the frequency domain diagram. Figure 5 、 Figure 6 and Figure 7 The power spectral density plots of the vertical, pitch, and roll accelerations of the semi-active and passive cabin mount systems derived from the test are shown. As can be seen from the plots, the control method employed in this study significantly optimizes vertical and pitch accelerations over the full frequency range compared to the passive method. While roll acceleration degrades somewhat at low frequencies and improves at high frequencies, the optimized performance occurs within the resonant peak range. Clearly, the control method employed in this study is effective.

[0099] In summary, the present invention has the following beneficial effects:

[0100] 1. The method of obtaining the cab acceleration posture information by the cab posture perception system in the present invention requires few peripherals, has a simple layout, occupies a small space, and has low occupation of the computing power resources of the vehicle-mounted ECU system.

[0101] 2. The mount-end attitude observation system of this invention uses a tracking differentiator to perform differential calculations and noise removal on the acquired displacement signal, enabling the acquisition of a relatively accurate relative velocity signal in real time. Furthermore, its iterative calculation structure only requires the retention of two acquisition points, the upper and lower points, saving memory space in the vehicle ECU system.

[0102] 3. The cab attitude suppression system of this invention does not rely on accurate modeling of heavy trucks. Its extended state observation module and nonlinear error feedback module establish a PD closed-loop control relationship between acceleration attitude variables and attitude suppression variables while compensating for dynamic disturbances and model uncertainties in the attitude direction, demonstrating robustness and adaptability.

[0103] 4. The damping force inverter in the present invention decouples the damping force into a control current in an explicit manner, making the decoupling operation process simpler and saving computing power resources of the vehicle ECU system.

[0104] 5. The present invention can achieve coupled control of the acceleration attitude of the heavy truck cab, avoiding the deterioration of the roll acceleration attitude while optimizing the vertical and pitch acceleration attitudes.

[0105] The above disclosure is merely one or more preferred embodiments of the present invention, and certainly cannot be used to limit the scope of the present invention. A person skilled in the art can understand that all or part of the processes of the above embodiments and equivalent changes made in accordance with the claims of the present invention still fall within the scope of the invention.

Claims

1. A suspension control method for coupling control of the acceleration posture of a heavy truck cab, characterized in that: The following steps are involved: Step 1: The cab attitude sensing system obtains the cab acceleration attitude signal; Step 2: Obtain the relative velocity signal of the mount end through the mount end state observation system; Step 3: The cab attitude suppression system calculates the attitude suppression amount; Step 4: Calculate the output damping force of each suspension end by the damping force distribution system; Step 5: The damping force inverter controls the continuously damping adjustable shock absorber at each suspension end.

2. The suspension control method for coupling control of the acceleration posture of a heavy truck cab according to claim 1, characterized in that: In step 1, the acceleration signal is obtained by installing the vertical vibration acceleration sensor at the passive end of the left rear, right front and right rear suspension system of the cab, and then the vertical, roll angle and pitch angle acceleration signals of the cab are obtained through attitude decoupling calculation.

3. The suspension control method for coupling control of the acceleration posture of a heavy truck cab as claimed in claim 1, characterized in that: In step 2, the relative displacement signals of the suspension ends are obtained by installing distance measuring sensors at the four suspension ends of the cab, and the relative speed signals of the left front, right front, left rear and right rear suspension ends of the cab are calculated.

4. The suspension control method for coupling control of the acceleration posture of a heavy truck cab as claimed in claim 1, characterized in that: The cab attitude suppression system includes a three-layer structure consisting of a vertical attitude suppressor, a pitch attitude suppressor, and a roll attitude suppressor. Each attitude suppressor layer converts the cab acceleration attitude signal in the corresponding direction into an attitude suppression value signal in that direction by constructing a closed-loop control iterative operation structure composed of an extended state observation module and a nonlinear error feedback module.

5. The suspension control method for coupling control of the acceleration posture of a heavy truck cab as claimed in claim 1, characterized in that: The damping force distribution system includes two parts: a decoupling module and a limiting module; the decoupling module decouples the attitude suppression signal into the output damping force distributed to each suspension end; the limiting module adjusts the output damping force distributed to the shock absorber at each suspension end so that it is within the output range of the shock absorber.

6. The suspension control method for coupling control of the acceleration posture of a heavy truck cab as claimed in claim 1, characterized in that: In step 5, the damping force inverter explicitly decouples the actual damping force, and the expression is: Among them, I i is the actual input current of a certain suspension end shock absorber; f ci is the actual output damping force of the shock absorber at a certain suspension end; In order to interpolate the external load characteristic curve of the shock absorber damping force, a positive parameter needs to be adjusted; exp() is a natural exponential function.

Images