A vehicle ride comfort control method matching a non-suspension electric skateboard chassis

Abstract

The present invention discloses a vehicle ride comfort control method matching a non-suspension electric skateboard chassis, which improves the ride comfort of the car by directly applying active control force to the car body using an electric hydraulic actuator controlled by a slide valve. First, a vertical and pitch two-degree-of-freedom half-car model is established, and a road surface shape laser measuring instrument is used to monitor road surface information in real time; then, the virtual control force of the vertical motion and the virtual control torque of the pitch motion of the vehicle are calculated based on an adaptive sliding mode control algorithm, and the algorithm can adaptively adjust the vehicle body mass and pitch moment of inertia; finally, the expected active control force of the electric hydraulic actuator and the slide valve stroke input that tracks the expected control force are calculated. The present invention will play a positive role in promoting the simplified integration of the entire vehicle chassis and the development of skateboard chassis technology.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle ride comfort control, and in particular to a vehicle ride comfort control method matched with a non-suspension electric skateboard chassis. Background Art

[0002] Vehicle ride smoothness is one of the most important performance indicators in vehicle performance evaluation. Traditional vehicles use suspension structures to attenuate and isolate various vibrations caused by uneven roads to improve vehicle ride smoothness. Emerging non-suspension vehicles using skateboard chassis have advantages such as high integration and high commonality. They can achieve separate decoupling development of the body and chassis, shorten the R&D cycle, reduce R&D costs, and adapt to the development needs of various vehicle models. The non-suspension structure can further save vehicle body space, but it cannot effectively isolate the disturbance of the road to the vehicle, and it is difficult to meet higher comfort and driving experience requirements. At the same time, the diverse vehicle adaptation characteristics also put forward higher requirements for the robustness of the control algorithm. Summary of the invention

[0003] In order to solve the above problems, the technical solution adopted by the present invention is: a vehicle ride comfort control method matching a non-suspension electric skateboard chassis, comprising the following steps:

[0004] 1) Establish a half-car model with two degrees of freedom in vertical and pitch, and simplify the force transmitted from the wheel to the car body into the spring elastic force F kw and the damping force F cw , where w = f, r represents the front wheel and the rear wheel respectively;

[0005] 2) Calculate the vehicle virtual vertical control force through the adaptive sliding mode control method;

[0006] 3) Calculate the vehicle virtual pitch control torque through the adaptive sliding mode control method;

[0007] 4) Calculate the expected active control force of the electro-hydraulic actuator;

[0008] 5) Calculate the spool valve stroke input of the electro-hydraulic actuator to ensure tracking of the desired active control force.

[0009] Preferably, the implementation process of step 1) is: the two-degree-of-freedom half-car model is represented as:

[0010]

[0011] Among them, m is the vehicle body mass, is the second derivative, z c is the vertical displacement of the vehicle, F z is the virtual control force for the vertical motion of the vehicle, is the pitch angle of the vehicle, I is the moment of inertia of the vehicle pitch motion, ΔF is the unknown disturbance force of the vehicle vertical motion and |ΔF|≤F′, ΔM is the unknown disturbance torque of the pitch motion and |ΔM|≤M′, F′ and M′ are known norm critical values, a and b are the distances from the center of the front and rear wheels to the center of mass of the vehicle body, respectively. is the virtual control torque of the vehicle pitch motion, F kf 、F kr and F cf 、F cr are the front and rear spring elastic forces and damping forces respectively, and the expressions are as follows:

[0012]

[0013] Among them, k f , k r is the front and rear elastic force stiffness coefficient, c f 、c r is the damping coefficient of the front and rear damping forces, measured by experiments; z w (w=f,r) is the vertical displacement of the road surface at the contact point, z f 、z r It is the vertical displacement of the road surface at the contact point between the front and rear wheels, measured by a road shape laser measuring instrument installed on the axle close to the wheels.

[0014] Preferably, the implementation process of step 2) is to define the sliding surface s1:

[0015]

[0016] Adaptive control method is used to estimate the vehicle mass m, taking is the estimated value of m, then the virtual vertical control force of the vehicle is:

[0017]

[0018] Where c1>0, k1>0, η1>F′ are preset control parameters;

[0019] Estimated vehicle mass The adaptive law is:

[0020]

[0021] Preferably, the implementation process of step 3) is to define the synovial surface s2:

[0022]

[0023] The vehicle virtual pitch control torque is:

[0024]

[0025] Among them, c2>0, k2>0, η2>M′ are preset control parameters. is the estimated value of I, The adaptive law is:

[0026]

[0027] Preferably, the expression of the desired active control force in step 4) is,

[0028]

[0029] Preferably, in step 5), a sliding mode control method is used to track the desired active control force, and a sliding mode surface s=F is defined. a -F i , (i=1,2), select the sliding mode reaching law μ>0 is the preset control parameter, then the slide valve stroke input control law is:

[0030]

[0031] Among them, F a is the output force of the electro-hydraulic actuator, F i (i=1,2) is the expected active control force, u is the slide valve stroke input, parameter α=4β / V t , V t is the volume of the hydraulic cylinder, β is the bulk elastic modulus of the hydraulic oil, A p is the piston area, z c is the vertical displacement of the vehicle, z w (w=f,r) is the vertical displacement of the road surface at the contact point between the front and rear wheels, is the derivative, C d is the servo valve unloading coefficient, W is the servo valve width, P s is the supply pressure, ρ is the oil density;

[0032] Preferably, the electro-hydraulic actuator satisfies:

[0033]

[0034] Compared with the prior art, the present invention adopts the above technical solution and has the following technical effects:

[0035] The present invention is based on an electric skateboard chassis-type vehicle with no suspension structure. The electric hydraulic actuator controlled by a slide valve directly applies active control force to the vehicle body to maintain the smoothness of the vehicle's ride, improve the space utilization of the vehicle, and play a positive role in promoting the simplified integration of the vehicle chassis and the development of skateboard chassis technology. The expected active control force is calculated by designing an adaptive sliding mode control method, and the real-time adaptability of the control algorithm is improved by real-time monitoring of road conditions. Compared with traditional suspension control algorithms, the robustness is stronger and more suitable for the characteristics of electric skateboard chassis structure vehicles adapting to diversified models. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a flow chart of a vehicle ride comfort control method matching a non-suspension electric skateboard chassis of the present invention;

[0037] Figure 2 It is a schematic diagram of a half-car model with two degrees of freedom in vertical and pitch. DETAILED DESCRIPTION

[0038] The present invention is further described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, rather than all 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.

[0039] The present invention discloses a vehicle ride comfort control strategy matching a suspension-free electric skateboard chassis. The suspension-free electric skateboard chassis uses an electric hydraulic actuator controlled by a slide valve to directly apply active control force to a vehicle body to maintain the driving comfort of the vehicle. Four electric hydraulic actuators are arranged, namely, right front, left front, right rear, and left rear. The right front and left front active hydraulic actuators generate the same active control force F1 and are arranged between a steering knuckle and a vehicle body. The right rear and left rear active hydraulic actuators generate the same active control force F2 and are directly arranged between axles and a vehicle body.

[0040] Active control force is generated by the designed ride control strategy, such as Figure 1 The method comprises the following steps:

[0041] Step 1: Create a half-car model with two degrees of freedom in vertical and pitch, such as Figure 2 As described above, the force transmitted from the wheel to the vehicle body is simplified to a spring elastic force and a damping force, and the two-degree-of-freedom half-car model can be expressed as:

[0042]

[0043] Among them, z c is the vertical displacement of the vehicle, is the pitch angle of the vehicle, m is the mass of the vehicle body, I is the moment of inertia of the vehicle pitch motion, ΔF is the unknown disturbance force of the vehicle vertical motion and |ΔF|≤F′, ΔM is the unknown disturbance torque of the pitch motion and |ΔM|≤M′, a and b are the distances from the center of the front and rear wheels to the center of the vehicle body mass, respectively, F z is the virtual control force for the vertical motion of the vehicle, is the virtual control torque of the vehicle pitch motion, F kf 、F kr and F cf 、F cr are the front and rear spring elastic forces and damping forces respectively, and the expressions are as follows:

[0044]

[0045] Among them, k f , k r and c f 、c r are the front and rear elastic stiffness coefficients and damping coefficients, which can be measured by experiments; z1 and z2 are the vertical displacements of the road surface at the contact points of the front and rear wheels, which are measured by a road surface shape laser measuring instrument installed on the axle close to the wheels;

[0046] Step 2: Calculate the virtual vertical control force of the vehicle;

[0047] An adaptive sliding mode control method is designed to calculate the virtual vertical control force of the vehicle, and the sliding mode surface is defined as follows:

[0048]

[0049] Adaptive control method is used to estimate the vehicle mass m, taking is the estimated value of m, and the control law of the vehicle virtual vertical control force is:

[0050]

[0051] Where c1>0, k1>0, η1>F′ are preset control parameters;

[0052] Estimated vehicle mass The adaptive law is:

[0053]

[0054] Defining the Lyapunov function in is the estimation error, then:

[0055]

[0056] It can be proved that the designed control law and adaptive law can make the closed-loop system asymptotically stable;

[0057] Step 3, calculating the vehicle virtual pitch control moment;

[0058] Use the same control method as step 2 to define the sliding surface The vehicle virtual pitch control torque control law is obtained as:

[0059]

[0060] Among them, c2>0, k2>0, η2>M′ are preset control parameters. is the estimated value of I, The adaptive law is:

[0061]

[0062] Step 4: Calculate the expected active control force of the electric hydraulic actuator. The relationship between the expected active control forces F1 and F2 of the front and rear actuators and the virtual control force and torque calculated in step 3 is as follows:

[0063]

[0064] Therefore, the expected output forces F1 and F2 of the front and rear actuators are expressed as:

[0065]

[0066] Step 5, calculating the slide valve stroke input of the electro-hydraulic actuator to ensure tracking of the desired active control force;

[0067] As a preferred solution of the present invention, this embodiment adopts an electric hydraulic actuator that conforms to the following dynamic model:

[0068]

[0069] where F a is the actuator output force, u is the slide valve stroke input, α=4β / V t , V t is the volume of the hydraulic cylinder, β is the bulk elastic modulus of the hydraulic oil, C d is the servo valve unloading coefficient, w is the servo valve width, A p is the piston area, P s is the supply pressure, ρ is the oil density, i=1,2;

[0070] As a preferred solution of the present invention, this embodiment adopts a sliding mode control method to track the desired active control force, and defines a sliding mode surface s = F a -F i , select the sliding mode reaching law μ>0 is the preset control parameter, then the slide valve stroke input control law is:

[0071]

[0072] The above embodiments are only for illustrating the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention.

Claims

1. A vehicle ride comfort control method for a non-suspension electric skateboard chassis, characterized in that: The following steps are involved: 1) Establish a half-car model with two degrees of freedom in vertical and pitch, and simplify the force transmitted from the wheel to the car body into the spring elastic force F kw and the damping force F cw , where w = f, r represents the front wheel and the rear wheel respectively; 2) Calculate the vehicle virtual vertical control force through the adaptive sliding mode control method; 3) Calculate the vehicle virtual pitch control torque through the adaptive sliding mode control method; 4) Calculate the expected active control force of the electro-hydraulic actuator; 5) Calculate the spool valve stroke input of the electro-hydraulic actuator to ensure tracking of the desired active control force; The implementation process of step 1) is: the two-degree-of-freedom half-car model is represented as: Where m is the vehicle mass, .. is the second derivative, z c is the vertical displacement of the vehicle, F z is the virtual control force for the vertical motion of the vehicle, is the pitch angle of the vehicle, I is the moment of inertia of the vehicle pitch motion, ΔF is the unknown disturbance force of the vehicle vertical motion and ΔF | ≤F′, ΔM is the unknown disturbance torque of the pitch motion and | ΔM | ≤M′, F′ and M′ are known norm critical values, a and b are the distances from the front and rear wheel centers to the vehicle body mass center, respectively. is the virtual control torque of the vehicle pitch motion, F kf 、F kr and F cf 、F cr are the front and rear spring elastic forces and damping forces respectively, and the expressions are as follows: Among them, k f , k r is the front and rear elastic force stiffness coefficient, c f 、c r is the damping coefficient of the front and rear damping forces, measured by experiments; z w (w=f,r) is the vertical displacement of the road surface at the contact point, z f 、z r It is the vertical displacement of the road surface at the contact point between the front and rear wheels, measured by a road surface shape laser measuring instrument installed on the axle close to the wheel; The implementation process of step 2) is to define the sliding surface s1: Adaptive control method is used to estimate the vehicle mass m, taking is the estimated value of m, then the virtual vertical control force of the vehicle is: Where c1>0, k1>0, η1>F′ are preset control parameters; Estimated vehicle mass The adaptive law is: The implementation process of step 3) is to define the synovial surface s2: The vehicle virtual pitch control torque is: Among them, c2>0, k2>0, η2>M′ are preset control parameters, is the estimated value of I, The adaptive law is: The expression of the expected active control force in step 4) is:

2. A vehicle ride comfort control method for a non-suspension electric skateboard chassis as claimed in claim 1, characterized in that: In step 5), the sliding mode control method is used to track the desired active control force, and the sliding mode surface s = F is defined. a -F i , (i=1,2), select the sliding mode reaching law μ>0 is the preset control parameter, then the slide valve stroke input control law is: Among them, F a is the output force of the electro-hydraulic actuator, F i (i=1,2) is the expected active control force, u is the slide valve stroke input, and parameter α=4β / V t , V t is the volume of the hydraulic cylinder, β is the bulk elastic modulus of the hydraulic oil, A p is the piston area, z c for. The vertical displacement of the vehicle, z w (w=f,r) is the vertical displacement of the road surface at the contact point between the front and rear wheels, (.) is the derivative, C d is the servo valve unloading coefficient, W is the servo valve width, P s is the supply pressure and ρ is the oil density.

3. A vehicle ride comfort control method for a non-suspension electric skateboard chassis as claimed in claim 2, characterized in that: The electro-hydraulic actuator meets the following requirements:

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