A collaborative control module, adaptive cruise system and control method thereof, and vehicle

Abstract

The present invention provides a coordinated control module, an adaptive cruise system, a control method thereof, and a vehicle. The adaptive cruise system includes a vehicle sensor module, a driving environment intelligent perception module, a vehicle state response estimation module, an adaptive cruise and controllable suspension coordinated control module, and a dynamic control module. The adaptive cruise control method comprises: adaptive cruise is performed based on a driver-set cruise speed, or based on a driver-set cruise comfort level, the adaptive cruise and controllable suspension system intelligently calculates an optimal cruise speed based on driving conditions and driver requirements to achieve adaptive cruise. During the cruise process, the controllable suspension is coordinated and controlled, adaptively switching suspension control parameters based on vehicle performance requirements under different driving conditions. The present invention can achieve coordinated control of adaptive cruise and controllable suspension, effectively improving ride comfort during the vehicle's adaptive cruise process while ensuring vehicle safety.

Description

Technical Field

[0001] The present invention belongs to the technical field of assisted driving and vehicle chassis dynamics control, and particularly relates to an adaptive cruise system and a control method thereof. Background Art

[0002] Adaptive cruise control is a crucial intelligent assistance system for current vehicle operations. It can significantly reduce fatigue during long-distance driving and provide drivers with a more relaxed and comfortable driving experience. Cruise control essentially refers to vehicle speed control, a component of vehicle longitudinal dynamics control. Current research on adaptive cruise control primarily focuses on speed tracking and obstacle avoidance, with little consideration of ride comfort and handling stability during cruise control. Vehicle ride comfort and handling stability involve vertical dynamics control. While controllable suspension systems can improve vertical dynamics during driving through semi-active / active control, the effectiveness of this control is significantly affected by vehicle speed. On the same road surface, higher speeds result in poorer ride comfort and handling stability. Current research has yet to provide an effective solution to the problem of coordinating adaptive cruise control with controllable suspension control to improve vertical dynamics during cruise control through coordinated longitudinal and vertical control. Summary of the Invention

[0003] In view of the shortcomings of the prior art, the present invention provides an adaptive cruise control system and a control method thereof, which effectively improve the vertical dynamics performance of a vehicle during cruising.

[0004] The present invention achieves the above technical objectives through the following technical means.

[0005] An adaptive cruise and controllable suspension collaborative control module, including an adaptive cruise control submodule and a suspension control submodule;

[0006] The adaptive cruise control submodule is used to process adaptive cruise control instructions, including cruise speed intelligent setting instructions, and calculate the optimal cruise speed during the cruise speed intelligent setting process;

[0007] The suspension control submodule switches corresponding controllable suspension control parameters according to the real-time dynamic performance requirements of the vehicle.

[0008] In the above technical solution, the adaptive cruise control submodule determines the expected weighted RMS value of the vehicle body center of mass based on the set target comfort level, and calculates the optimal cruising speed in combination with the current driving road surface information.

[0009] In the above technical solution, the controllable suspension control parameters are determined by:

[0010] Combined with road surface information and vehicle speed, the vehicle dynamics performance requirements under different driving conditions are determined, and a comprehensive performance evaluation function is designed to characterize the dynamics performance of different vehicles. The comprehensive performance evaluation function considers both vehicle ride comfort and handling stability.

[0011] Taking the comprehensive performance evaluation function as the fitness function, an optimization algorithm is used to find the optimal solution and obtain the suspension control parameters under different vehicle dynamic performance requirements.

[0012] An adaptive cruise system includes the above-mentioned collaborative control module.

[0013] In the above technical solution, the adaptive cruise and controllable suspension coordinated control module receives signals from the sensor module, the driving environment intelligent perception module and the vehicle state response information estimation module, and sends the optimal cruise speed to the power control module.

[0014] In the above technical solution, the vehicle sensor module is used to obtain vehicle speed and brake pedal signals, road surface measurement signals and vehicle distance signals, and vehicle dynamic response signals.

[0015] In the above technical solution, the driving environment intelligent perception module obtains road surface information and the preceding vehicle's driving behavior signal based on the road surface measurement signal and the vehicle distance signal.

[0016] In the above technical solution, the vehicle state response information estimation module obtains vehicle state information based on road surface information and vehicle dynamic response signals.

[0017] In the above technical solution, the power control module sends a throttle opening signal to the power system and a brake pressure signal to the brake system based on the optimal cruising speed.

[0018] A vehicle comprises the above-mentioned adaptive cruise control system.

[0019] A control method for an adaptive cruise control system, specifically comprising:

[0020] The adaptive cruise control submodule determines the expected RMS value of the weighted acceleration of the vehicle center of mass based on the set target comfort level, and calculates the optimal cruising speed based on the expected RMS value of the weighted acceleration of the vehicle center of mass and the current driving road information.

[0021] Furthermore, it also includes:

[0022] The suspension control submodule determines the current vehicle dynamic performance requirements based on the current driving speed and road surface information. Based on the current vehicle dynamic performance requirements, it switches the corresponding controllable suspension control parameters. According to the adopted control strategy, controllable suspension control parameters and current vehicle status information, it calculates the ideal suspension control force and sends a control signal to the vehicle suspension system to track the ideal suspension control force and perform vibration suppression.

[0023] Furthermore, the optimal cruising speed is obtained by the following method:

[0024] The simulation obtains the RMS value of the weighted acceleration of the vehicle's center of mass under different road excitations and driving speeds. The functional relationship between the RMS value of the weighted acceleration of the vehicle's center of mass under different driving conditions and the driving speed is fitted, which is the formula for calculating the ideal cruising speed.

[0025] Select an ideal cruising speed calculation formula for the corresponding road surface based on the road surface information, then determine the expected weighted RMS value of the vehicle center of mass based on the ride comfort level selected by the driver, and substitute this value into the selected ideal cruising speed calculation formula to calculate the ideal cruising speed;

[0026] The ideal cruising speed is substituted into the simulation model to obtain the root mean square value of the suspension dynamic travel and wheel dynamic load under driving conditions. If there is a risk of hitting the limit block or jumping off the ground, the ideal cruising speed is compensated to obtain the optimal cruising speed.

[0027] Furthermore, the risk of hitting the limit block is determined by the following method: if the root mean square value of the suspension dynamic stroke exceeds one-third of the maximum working stroke, there is a 99.7% probability that the suspension will hit the limit block, and compensation for the ideal cruising speed is required; otherwise, no compensation is made for the vehicle speed.

[0028] Furthermore, the risk of the wheel jumping off the ground is determined by the following method: if the root mean square value of the wheel dynamic load exceeds one-third of the wheel static load, there is a 99.7% probability that the wheel will jump off the ground, and compensation for the ideal cruising speed is required; otherwise, no compensation is made for the speed.

[0029] Furthermore, the compensation for the ideal cruising speed is achieved by the following method:

[0030]

[0031] In the formula, rms(F d_i ) and rms(f d_i ) are the root mean square values ​​of the dynamic load of each wheel and the dynamic travel of the suspension, F start_i is the static load of each wheel, f max is the maximum working stroke of the suspension, i=1, 2, 3, 4, corresponding to the four wheels respectively, v 理想It is the ideal cruising speed.

[0032] Furthermore, the controllable suspension control parameters are determined by:

[0033] Combined with road surface information and vehicle speed, the vehicle dynamics performance requirements under different driving conditions are determined, and a comprehensive performance evaluation function is designed to characterize the dynamics performance of different vehicles. The comprehensive performance evaluation function considers both vehicle ride comfort and handling stability.

[0034] Taking the comprehensive performance evaluation function P as the fitness function, an optimization algorithm is used to find the optimal solution and obtain the suspension control parameters under different vehicle dynamic performance requirements.

[0035] Furthermore, the expression of the comprehensive performance evaluation function P is:

[0036]

[0037] Where w1 and w2 are the weight coefficients of ride comfort and handling stability respectively. and rms(F d ) are the average values ​​of the weighted acceleration of the vehicle body center of mass and the root mean square value of the dynamic loads on the four wheels, and rms(F df ) are the relevant values ​​of the reference passive suspension.

[0038] Furthermore, the vehicle dynamics performance requirements under different driving conditions are specifically as follows: when the vehicle is traveling at a speed greater than or equal to 90 km / h, the vehicle dynamics performance requirement is handling stability; when the vehicle is traveling at a speed less than 30 km / h, the vehicle dynamics performance requirement is ride comfort.

[0039] Furthermore, the control strategy includes a model predictive control strategy, a linear quadratic optimal control strategy or an improved skyhook control strategy.

[0040] Furthermore, the priority of vehicle dynamics performance requirements is higher than the priority of comfort requirements.

[0041] The beneficial effects of the present invention are:

[0042] (1) The present invention uses an adaptive cruise control submodule to calculate the optimal cruise speed, and a suspension control submodule switches corresponding controllable suspension control parameters according to the real-time dynamic performance requirements of the vehicle. Adaptive cruise and controllable suspension coordinated control is performed based on the optimal cruise speed and the controllable suspension control parameters, effectively improving ride comfort and handling stability issues caused by the driver's subjective behavior during the cruise speed setting process.

[0043] (2) The present invention determines the expected weighted RMS value of the vehicle center of mass based on the set target comfort level, and calculates the optimal cruising speed based on the expected weighted RMS value of the vehicle center of mass and the current road surface information to ensure the vertical dynamic performance of the vehicle during cruising;

[0044] (3) The present invention determines whether to compensate for the ideal cruising speed by judging the risk of the suspension hitting the limit block or the wheel jumping off the ground, thereby improving the vehicle's ride comfort as much as possible while ensuring vehicle safety and handling stability;

[0045] (4) The present invention designs a comprehensive performance evaluation function that characterizes the dynamic performance of different vehicles. The comprehensive performance evaluation function is used as the fitness function, and an optimization algorithm is used to search for the optimal suspension control parameters under different vehicle dynamic performance requirements. The vehicle dynamic performance requirements under different driving conditions (vehicle speed and road surface) are different. Based on the optimized control parameters, the vehicle suspension system can be targetedly controlled according to the actual driving conditions to achieve the optimal vertical comprehensive performance of the vehicle under different driving conditions.

[0046] (5) The sensor module of the present invention includes a vehicle body acceleration sensor, a wheel acceleration sensor, and a binocular camera; the vehicle body acceleration sensor obtains vehicle body acceleration, the wheel acceleration sensor obtains wheel acceleration, and the vehicle body acceleration and wheel acceleration are used to estimate the state variables of the vehicle during driving. The state variables are combined with the controllable suspension control parameters to calculate the ideal suspension control force; the binocular camera collects the current driving road surface information for analyzing the real-time dynamic performance requirements of the vehicle, and can obtain the road surface information in front of the vehicle in advance. The suspension control performed on this basis is real-time control, and the control effect is significant;

[0047] (6) The adaptive cruise control command of the present invention includes an intelligent cruise speed setting command. When the intelligent cruise speed setting command is executed, the cruise speed is intelligently set and the optimal cruise speed and ideal suspension control force are determined. Compared with traditional adaptive cruise control, the vehicle comfort can be autonomously selected during the adaptive cruise process.

[0048] (7) The present invention determines the risk of the suspension hitting the limit block or the wheel jumping off the ground based on the "3σ principle" in random process theory. The risk judgment obtained in this way has a high credibility of 99.7%;

[0049] (8) The present invention calculates the vehicle speed compensation amount based on the suspension dynamic travel and the root mean square value of the wheel dynamic load at the current vehicle speed to obtain the optimal cruising speed. Through vehicle speed compensation, the safety and handling stability of the vehicle during adaptive cruising can be ensured;

[0050] (9) The present invention designs a comprehensive performance evaluation function that characterizes different vehicle performances for different suspension control objectives. The comprehensive performance evaluation function is used as a fitness function parameter optimization range, and a genetic algorithm is used to optimize the suspension control parameters under various driving conditions to obtain optimized control parameters. Based on the optimized control parameters, the vehicle suspension system can be targetedly controlled according to the actual driving conditions to achieve optimal vertical comprehensive performance of the vehicle under different driving conditions.

[0051] (10) The vehicle dynamics performance requirements under different driving conditions in the present invention are specifically as follows: when the vehicle is traveling at high speed on a flat road, the vehicle dynamics performance requirement is handling stability; when the vehicle is traveling on a bad road, the vehicle dynamics performance requirement is ride comfort; through the precise division of performance requirements, the suspension control targets under different driving conditions (vehicle speed and road surface) can be determined, providing a reasonable basis for the optimization of suspension control parameters. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. 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.

[0053] Figure 1 This is a schematic diagram of the adaptive cruise control system architecture of the present invention;

[0054] Figure 2 This is a flow chart of the adaptive cruise coordinated control method of the present invention;

[0055] Figure 3 This is a flow chart of the method for calculating the optimal cruising speed of the present invention;

[0056] Figure 4 This is a flow chart for optimizing the control parameters of the controllable suspension according to the present invention;

[0057] Figure 5 is a graph showing the relationship between the weighted root mean square value of the vehicle center of mass acceleration and the vehicle speed under various driving conditions described in the present invention;

[0058] Figure 6 This is a curve diagram showing the relationship between the vehicle speed obtained by fitting and the root mean square value of the weighted acceleration of the vehicle body center of mass. DETAILED DESCRIPTION

[0059] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be further described below with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0060] like Figure 1 As shown, an adaptive cruise control system provided by an embodiment of the present invention includes a vehicle sensor module, a driving environment intelligent perception module, a vehicle state response information estimation module, an adaptive cruise control and controllable suspension coordinated control module and a power control module; the adaptive cruise control and controllable suspension coordinated control module is respectively connected to the vehicle sensor module, the driving environment intelligent perception module, the vehicle state response information estimation module and the power control module.

[0061] The vehicle sensor module is used to collect vehicle-related data required for road surface information recognition, vehicle state response information estimation, and coordinated control of adaptive cruise control and controllable suspension. In this embodiment of the present invention, the vehicle sensor module includes a body acceleration sensor, wheel acceleration sensors, a binocular camera, a millimeter-wave radar, a brake pedal sensor, a brake pressure sensor, and an engine speed sensor.

[0062] The intelligent driving environment perception module identifies road information based on binocular cameras and the driving status of the preceding vehicle based on millimeter-wave radar, and transmits relevant information to the vehicle state response information estimation module and the adaptive cruise and controllable suspension collaborative control module, providing data support for vehicle state variable estimation and adaptive cruise and controllable suspension collaborative control.

[0063] The vehicle state response information estimation module estimates the vehicle state information during driving in real time based on the signals from the body acceleration sensor and wheel acceleration sensor (i.e., the vehicle dynamic response signal) and the road surface information output by the driving environment intelligent perception module, providing front-end information for the adaptive cruise and controllable suspension collaborative control module.

[0064] The adaptive cruise and controllable suspension coordinated control module consists of two submodules: the adaptive cruise control module and the suspension control module. The adaptive cruise control submodule is responsible for processing adaptive cruise control commands issued by the driver and calculating the optimal cruise speed during the adaptive cruise intelligent speed setting process. The suspension control submodule is responsible for issuing output force control commands to the suspension system based on the vehicle dynamics performance requirements and driver comfort requirements during driving. The vehicle dynamics performance requirements take precedence over the driver comfort requirements, and the vehicle dynamics performance requirements are determined based on road surface information and vehicle speed. In this embodiment of the present invention, the adaptive cruise control commands issued by the driver include adaptive cruise start commands, adaptive cruise end commands, manual cruise speed setting commands, and intelligent cruise speed setting commands.

[0065] The power control module is used to send throttle opening control instructions to the power system and brake pressure control instructions to the braking system based on the optimal cruising speed given by the adaptive cruise control submodule in the adaptive cruise and controllable suspension collaborative control module, the brake pressure collected in real time by the brake pressure sensor, and the engine speed collected in real time by the engine speed sensor.

[0066] See Figure 1 For the adaptive cruise control system of the embodiment of the present invention, the vehicle sensor module sends the vehicle speed and brake pedal signals (collected by the brake pedal sensor) to the adaptive cruise and controllable suspension coordinated control module, sends the road measurement signal and vehicle distance signal to the driving environment intelligent perception module, and sends the vehicle dynamic response signal to the vehicle state response information estimation module. The driving environment intelligent perception module sends the road information signal to the vehicle state response information estimation module and sends the road information signal and the preceding vehicle driving behavior signal to the adaptive cruise and controllable suspension coordinated control module respectively. The vehicle state response information estimation module sends the vehicle state information to the adaptive cruise and controllable suspension coordinated control module. The adaptive cruise and controllable suspension coordinated control module sends the optimal cruise speed signal to the power control module and the target control force signal to the suspension system respectively. The power control module sends the throttle opening signal to the power system and the brake pressure signal to the brake system respectively.

[0067] The adaptive cruise control and controllable suspension system of an embodiment of the present invention, through the configuration of an adaptive cruise control and controllable suspension collaborative control module, issues control instructions to the powertrain, braking system, and suspension system respectively according to the vehicle speed requirement of the adaptive cruise control submodule and the control force requirement of the suspension control submodule. On the basis of achieving adaptive cruise control, the vehicle vertical dynamic performance during the adaptive cruise process is improved through the collaborative control of adaptive cruise control and controllable suspension.

[0068] Based on the above adaptive cruise control system, the embodiment of the present invention also provides a coordinated control method of the adaptive cruise control system, the process of which is as follows: Figure 2 As shown, the specific steps include:

[0069] Step 1), when the vehicle is driving on the road, the adaptive cruise control mode is turned on, and the adaptive cruise control submodule receives the driver's control signal. If the driver chooses to manually set the cruise speed, go to step 2) and step 10); if the driver chooses to intelligently set the cruise speed, go to step 7);

[0070] Step 2): If the vehicle ahead is traveling at a constant speed, the power control module sends a control signal to the power system to maintain the current engine throttle opening and keep a safe distance from the vehicle ahead, and then proceed to step 6); if the vehicle ahead is traveling at a non-uniform speed, then proceed to step 3);

[0071] In step 3), if the vehicle ahead is decelerating, the power control module sends control signals to the power system and the braking system respectively, evenly reducing the engine throttle opening and increasing the brake pressure, adjusting the current vehicle speed to maintain a safe distance from the vehicle ahead, and then proceeding to step 6); if the vehicle ahead is accelerating, then proceeding to step 4);

[0072] Step 4): If the current vehicle speed is consistent with the cruising speed set by the driver, the power control module sends a control signal to the power system to maintain the current engine throttle opening, and the process goes to step 6); if the current vehicle speed is inconsistent with the cruising speed set by the driver, the process goes to step 5);

[0073] Step 5), if the current vehicle speed is greater than the cruising speed set by the driver, the power control module sends a control signal to the power system to evenly reduce the engine throttle opening, and the process proceeds to step 6); if the current vehicle speed is less than the cruising speed set by the driver, the power control module sends a control signal to the power system to evenly increase the engine throttle opening, and the process proceeds to step 6);

[0074] Step 6), if the driver does not choose to exit the adaptive cruise control mode, go to step 2), otherwise the adaptive cruise control submodule receives the driver's control signal (brake pedal signal) and exits this service;

[0075] Step 7), the adaptive cruise control submodule in the adaptive cruise and controllable suspension coordinated control module determines the expected body center of mass weighted acceleration root mean square value according to the target comfort level set by the driver, and then goes to step 8);

[0076] Step 8), the adaptive cruise control submodule in the adaptive cruise and controllable suspension coordinated control module determines the current driving road surface information based on the road surface information recognized by the binocular camera in the sensor module, and then goes to step 9) and step 10);

[0077] Step 9), the adaptive cruise control submodule in the adaptive cruise and controllable suspension coordinated control module calculates the optimal cruising speed based on the expected weighted acceleration root mean square value of the vehicle center of mass and the current driving road surface information, and then goes to step 2);

[0078] Step 10), the suspension control submodule in the adaptive cruise and controllable suspension coordinated control module determines the current vehicle dynamics performance requirements based on the current driving speed and road surface information, and then goes to step 11);

[0079] Step 11), the suspension control submodule in the adaptive cruise and controllable suspension coordinated control module switches the corresponding controllable suspension control parameters according to the current vehicle dynamics performance requirements, and then goes to step 12);

[0080] In step 12), the suspension control submodule in the adaptive cruise control and controllable suspension coordinated control module calculates the ideal suspension control force based on the adopted control strategy (e.g., model predictive control strategy, linear quadratic optimal control strategy, improved skyhook control strategy, etc.) and the controllable suspension control parameters determined in step 11) combined with the current vehicle state information, and then proceeds to step 13);

[0081] Step 13), the suspension control submodule in the adaptive cruise and controllable suspension coordinated control module sends a control signal to the vehicle suspension system to track the ideal suspension control force and perform vibration suppression, and then proceeds to step 14);

[0082] Step 14), if the trip is not over, go to step 10), otherwise end this service.

[0083] In a method for cooperatively controlling an adaptive cruise control and a controllable suspension according to the present invention, a control instruction priority based on the driving behavior of a preceding vehicle is higher than a control instruction priority based on the current driving state of the vehicle.

[0084] Figure 3 FIG. 1 is a flow chart of a method for calculating an optimal cruising speed according to an embodiment of the present invention, which specifically includes the following steps:

[0085] Step 1) divides the comfort level according to the weighted RMS value of the vehicle center of mass, and then proceeds to step 2); in the real-time embodiment of the present invention, the mapping relationship between the weighted RMS value of the vehicle center of mass and the comfort level is determined according to the international standard ISO 2631 as shown in Table 1:

[0086] Table 1 Comfort level and weighted RMS value of vehicle center of mass acceleration

[0087]

[0088] Step 2) Construct a road surface excitation model under different driving conditions, and go to step 3); the embodiment of the present invention divides different driving roads according to the road surface roughness level, and takes the three common road levels A, B, and C as examples for explanation. First, a single-wheel road surface excitation model is constructed using the filtered white noise method. Then, based on this, a four-wheel road surface excitation model is constructed based on the coherence principle of the road surface excitation on both sides of the left and right wheels and the wheelbase delay principle of the road surface excitation on the front and rear axles (which is the existing technology). The expression of the single-wheel road surface excitation model based on the filtered white noise method is: Where f0 is the lower cutoff frequency, which is generally 0.011Hz; n0 is the reference spatial frequency, n0 = 0.1m -1 ; w(t) is a white noise random signal in the time domain; z r (t) is the road roughness signal (road vertical displacement signal) in the time domain; v is the vehicle speed; G q (n0) is the road surface roughness coefficient, and the specific values ​​are shown in Table 2;

[0089] Table 2 Road surface roughness classification standards

[0090]

[0091] Step 3) constructs a reference model of the vehicle passive suspension system, and then proceeds to step 4); the embodiment of the present invention is described using the linearized vehicle passive suspension system as an example, and the differential equation of motion of the vehicle center of mass is:

[0092]

[0093] The differential equations of motion of the unsprung masses of each suspension are as follows:

[0094]

[0095] Where, the mass displacement of each suspension spring is:

[0096]

[0097] Wherein, the suspension force includes the spring force and the damping force:

[0098]

[0099] Where m s is the sprung mass of the vehicle; m ui (i=1,2) is the unsprung mass of the front and rear wheels; I θ is the pitch moment of inertia of the vehicle body; is the body roll moment of inertia; a is the distance from the body center of mass to the front axle; b is the distance from the body center of mass to the rear axle; B f B is the front wheel track; r is the rear wheel track; ci (i=1,2) is the damping coefficient of the front and rear suspension; k si (i=1,2) is the front and rear suspension stiffness; k t is the tire stiffness; θ is the vehicle body pitch angle; is the vehicle body pitch angular acceleration; is the body roll angle; is the vehicle body roll acceleration; z si (i=1,2,3,4) is the displacement of the connection between each suspension and the vehicle body; z ui (i=1,2,3,4) is the unsprung mass displacement of each wheel; z ri (i=1, 2, 3, 4) is the road surface input for each wheel. The specific parameters used in the embodiment of the present invention are shown in Table 3; F LF is the left front suspension force, F RF is the right front suspension force, F LR is the left rear suspension force, F RR is the right rear suspension force, z s is the displacement of the vehicle’s center of mass, is the vehicle center of mass acceleration, (i=1,2,3,4) is the speed of the connection between each suspension and the vehicle body, is the unsprung mass speed of each wheel;

[0100] Table 3 Vehicle passive suspension system parameters

[0101]

[0102] Step 4) Using dynamics simulation software, simulate the dynamic performance of the vehicle's passive suspension under different driving conditions and speeds. The simulation time is set to 5 seconds. The weighted acceleration of the vehicle's center of mass, the suspension's dynamic travel, and the root mean square value of the wheel's dynamic load under different driving conditions on each driving condition are obtained, and then proceed to step 5);

[0103] Step 5) Based on the simulation results, a curve of the relationship between the weighted RMS acceleration of the vehicle body center of mass and the vehicle speed under different driving conditions is plotted. In the embodiment of the present invention, the curve of the relationship between the weighted RMS acceleration of the vehicle body center of mass and the vehicle speed under each driving condition is obtained as follows: Figure 5 As shown, go to step 6);

[0104] Step 6) Fit the above relationship curve to obtain the comparison between the fitting curve and the simulation curve. Figure 6 As shown in Table 4, the function of the vehicle speed changing with the weighted RMS acceleration of the vehicle center of mass under each driving condition is used to calculate the ideal cruising speed for comfort in an embodiment of the present invention.

[0105] Table 4 Calculation formula for ideal cruising speed based on comfort

[0106]

[0107] Step 7) Based on the identified road condition information, determine the function of the weighted RMS acceleration of the vehicle center of mass as a function of vehicle speed on the corresponding road surface, and calculate the ideal cruising speed based on the expected RMS acceleration of the vehicle center of mass at the driver's set comfort level, and then proceed to Step 8);

[0108] Step 8) Substitute the ideal cruising speed into the simulation model (the reference model of the vehicle passive suspension system) and simulate to obtain the root mean square value of each suspension dynamic stroke and wheel dynamic load under the driving condition. Determine whether each suspension dynamic stroke and wheel dynamic load root mean square value exceeds the boundary. If either exceeds the boundary, go to step 9), otherwise go to step 10). In this embodiment of the present invention, the boundary values ​​of each suspension dynamic stroke and wheel dynamic load root mean square value are determined based on the "3σ principle" in random process theory. That is, if each suspension dynamic stroke or wheel dynamic load root mean square value exceeds one-third of the maximum working stroke of the suspension or the static load of the wheel, there is a 99.7% probability that the suspension will hit the limit block and there is a 99.7% probability that the wheel will jump off the ground. The corresponding boundaries are determined accordingly;

[0109]

[0110] In the formula, rms(f d_i ) is the root mean square value of each suspension travel, f max is the maximum working stroke of the suspension, rms(F d_i ) is the root mean square value of the dynamic load of each wheel, F start_i =(m si +m ui )·g is the static load of the wheel, m si (i=1,2,3,4) is the sprung mass of each wheel. The sprung mass of the left and right wheels of the front / rear axle is equal. m s1 =m s2 =377.5kg, m s3 =m s4 =312.5kg;

[0111] Step 9) Calculate the speed compensation based on the suspension travel and the RMS value of the wheel dynamic load at the current vehicle speed to obtain the optimal cruising speed and proceed to step 10). The specific calculation method is as follows:

[0112]

[0113] Where, v 理想 is the ideal cruising speed calculated in step 6), v 最优is the optimal cruising speed after compensation, i=1, 2, 3, 4 correspond to the four wheels respectively;

[0114] Step 10), output the optimal cruising speed.

[0115] Figure 4 FIG2 is a flow chart of a control parameter optimization method for a controllable suspension according to an embodiment of the present invention. In the embodiment of the present invention, the controllable suspension system uses a magnetorheological damper with adjustable damping as an actuator and utilizes an improved skyhook control strategy to control the suspension for vibration suppression. The method includes the following steps:

[0116] In step 1), the vehicle dynamics performance under different driving conditions is analyzed by combining the driving road surface information and the vehicle speed to obtain the suspension control target under each driving state, and then the process proceeds to step 2). The specific control targets determined in this embodiment of the present invention are shown in Table 5.

[0117] Table 5 Vehicle dynamics performance requirements under different driving conditions

[0118]

[0119] Step 2) Design a comprehensive performance evaluation function that characterizes different vehicle performances for different suspension control objectives, and then proceed to step 3); the comprehensive performance evaluation function designed in the embodiment of the present invention is as follows:

[0120]

[0121] Where w1 and w2 are the weight coefficients of ride comfort and handling stability respectively. and rms(F d ) are the average values ​​of the weighted acceleration of the vehicle body center of mass and the root mean square value of the dynamic loads on the four wheels, and rms(F df ) is the relevant value of the reference passive suspension. Based on the vehicle dynamics performance requirements under different driving conditions determined in step 1), the weight coefficients under different control objectives are obtained as shown in Table 6;

[0122] Table 6 Weight coefficients under different control objectives

[0123]

[0124] Step 3) Construct road excitation models under different driving conditions, using the same modeling method as in the optimal cruise speed calculation process, and then go to step 4);

[0125] Step 4) constructs a full-vehicle magnetorheological semi-active suspension model (a type of full-vehicle controllable suspension system model) including a magnetorheological damper, and proceeds to step 5); in the embodiment of the present invention, a full-vehicle seven-degree-of-freedom model is used to optimize the controllable suspension control parameters. The center of mass motion differential equation of the full-vehicle magnetorheological semi-active suspension model is as follows:

[0126]

[0127] The differential equations of motion of the unsprung masses of each suspension are as follows:

[0128]

[0129] Where, the mass displacement of each suspension spring is:

[0130]

[0131] Where the suspension force includes the spring force and the actuator force:

[0132]

[0133] Where, F i (i=1,2,3,4) is the output force of the magnetorheological damper. Other parameters are the same as those of the passive suspension. Under the improved skyhook control:

[0134]

[0135] Where c pi is the passive damping coefficient, c si is the ceiling damping coefficient, c min is the minimum damping coefficient of the magnetorheological damper. In the embodiment of the present invention, c min is 700N·s / m, and the front and rear suspensions use the same control parameters. In this embodiment of the present invention, the control parameters that need to be determined include two groups, namely, the front suspension control parameters (c p1 ,c s1 ) and rear suspension control parameters (c p2 ,c s2 );

[0136] Step 5), according to the external characteristic parameters of the magnetorheological damper used in the embodiment of the present invention, the optimization range of the control parameters is determined to be 700N·s / m≤c pi ≤2000N·s / m and 1000N·s / m≤c si ≤4000N·s / m, go to step 6);

[0137] Step 6) In this embodiment of the present invention, the comprehensive performance evaluation function designed in step 2) is used as the fitness function. Within the parameter optimization range determined in step 5), a genetic algorithm is used to optimize the suspension control parameters under various driving conditions to obtain optimized control parameters, and the process then proceeds to step 7);

[0138] Step 7), substitute the optimized control parameters into the simulation model (full vehicle magnetorheological semi-active suspension model) to verify the dynamic performance. If the comprehensive performance is optimized, go to step 8), otherwise go to step 6);

[0139] Step 8) Construct an optimal control parameter set for the suspension. The optimized control parameters in the embodiment of the present invention are shown in Table 7.

[0140] Table 7 Optimized suspension control parameters (c p1 , c s1 ), (c p2 , c s2 )

[0141]

[0142] The embodiments described are preferred implementations of the present invention, but the present invention is not limited to the above implementations. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention are within the scope of protection of the present invention.

Claims

1. An adaptive cruise control and controllable suspension collaborative control module, characterized in that: Includes adaptive cruise control submodule and suspension control submodule; The adaptive cruise control submodule is used to process adaptive cruise control instructions, including cruise speed intelligent setting instructions, and calculate the optimal cruise speed during the cruise speed intelligent setting process; The suspension control submodule switches corresponding controllable suspension control parameters according to the real-time dynamic performance requirements of the vehicle; The adaptive cruise control submodule determines the expected weighted acceleration root mean square value of the vehicle body center of mass based on the set target comfort level, and calculates the optimal cruising speed based on the current driving road surface information; The optimal cruising speed is obtained by the following method: The simulation obtains the RMS value of the weighted acceleration of the vehicle's center of mass under different road excitations and driving speeds. The functional relationship between the RMS value of the weighted acceleration of the vehicle's center of mass under different driving conditions and the driving speed is fitted, which is the formula for calculating the ideal cruising speed. Select an ideal cruising speed calculation formula for the corresponding road surface based on the road surface information, then determine the expected weighted RMS value of the vehicle center of mass based on the ride comfort level selected by the driver, and substitute this value into the selected ideal cruising speed calculation formula to calculate the ideal cruising speed; The ideal cruising speed is substituted into the simulation model to obtain the root mean square value of the suspension dynamic travel and wheel dynamic load under driving conditions. If there is a risk of hitting the limit block or jumping off the ground, the ideal cruising speed is compensated to obtain the optimal cruising speed.

2. The collaborative control module according to claim 1, characterized in that: The controllable suspension control parameters are determined as follows: Combined with road surface information and vehicle speed, the vehicle dynamics performance requirements under different driving conditions are determined, and a comprehensive performance evaluation function is designed to characterize the dynamics performance of different vehicles. The comprehensive performance evaluation function considers both vehicle ride comfort and handling stability. Taking the comprehensive performance evaluation function as the fitness function, an optimization algorithm is used to find the optimal solution and obtain the suspension control parameters under different vehicle dynamic performance requirements.

3. An adaptive cruise control system, characterized in that: Includes the collaborative control module described in any one of claims 1-2.

4. The adaptive cruise control system according to claim 3, characterized in that: The adaptive cruise and controllable suspension coordinated control module receives signals from the sensor module, the driving environment intelligent perception module and the vehicle state response information estimation module, and sends the optimal cruise speed to the power control module.

5. The adaptive cruise control system according to claim 4, characterized in that: The sensor module is used to obtain vehicle speed and brake pedal signals, road surface measurement signals and vehicle distance signals, and vehicle dynamic response signals.

6. The adaptive cruise control system according to claim 5, characterized in that: The driving environment intelligent perception module obtains road surface information and a preceding vehicle driving behavior signal based on a road surface measurement signal and a vehicle distance signal.

7. The adaptive cruise control system according to claim 6, characterized in that: The vehicle state response information estimation module obtains vehicle state information based on road surface information and vehicle dynamic response signals.

8. The adaptive cruise control system according to claim 7, characterized in that: The power control module sends a throttle opening signal to the power system and a brake pressure signal to the brake system based on the optimal cruising speed.

9. A means of transport, characterized in that: The adaptive cruise control system comprises the adaptive cruise control system according to any one of claims 3 to 8.

10. A control method for an adaptive cruise control system, characterized in that: The adaptive cruise control submodule determines the expected RMS value of the weighted acceleration of the vehicle's center of mass based on the set target comfort level, and calculates the optimal cruising speed based on the expected RMS value of the weighted acceleration of the vehicle's center of mass and the current road surface information; The optimal cruising speed is obtained by the following method: The simulation obtains the RMS value of the weighted acceleration of the vehicle's center of mass under different road excitations and driving speeds. The functional relationship between the RMS value of the weighted acceleration of the vehicle's center of mass under different driving conditions and the driving speed is fitted, which is the formula for calculating the ideal cruising speed. Select an ideal cruising speed calculation formula for the corresponding road surface based on the road surface information, then determine the expected weighted RMS value of the vehicle center of mass based on the ride comfort level selected by the driver, and substitute this value into the selected ideal cruising speed calculation formula to calculate the ideal cruising speed; The ideal cruising speed is substituted into the simulation model to obtain the root mean square value of the suspension dynamic travel and wheel dynamic load under driving conditions. If there is a risk of hitting the limit block or jumping off the ground, the ideal cruising speed is compensated to obtain the optimal cruising speed.

11. The control method according to claim 10, characterized in that: Also includes: The suspension control submodule determines the current vehicle dynamic performance requirements based on the current driving speed and road surface information. Based on the current vehicle dynamic performance requirements, it switches the corresponding controllable suspension control parameters. According to the adopted control strategy, controllable suspension control parameters and current vehicle status information, it calculates the ideal suspension control force and sends a control signal to the vehicle suspension system to track the ideal suspension control force and perform vibration suppression.

12. The control method according to claim 10, characterized in that: The risk of hitting the limit block is determined by the following method: if the root mean square value of the suspension dynamic stroke exceeds one-third of the maximum working stroke, there is a 99.7% probability that the suspension will hit the limit block, and compensation for the ideal cruising speed is required; otherwise, no speed compensation is made.

13. The control method according to claim 10, characterized in that: The risk of the wheel jumping off the ground is determined by the following method: if the root mean square value of the wheel dynamic load exceeds one-third of the wheel static load, there is a 99.7% probability that the wheel will jump off the ground, and compensation for the ideal cruising speed is required; otherwise, no speed compensation is required.

14. The control method according to claim 13, characterized in that: The compensation for the ideal cruising speed is achieved by the following method: In the formula, rms(F d_i ) and rms(f d_i ) are the root mean square values ​​of the dynamic load of each wheel and the dynamic travel of the suspension, F start_i is the static load of each wheel, f max is the maximum working stroke of the suspension, i=1, 2, 3, 4, corresponding to the four wheels respectively, v 理想 It is the ideal cruising speed.

15. The control method according to claim 11, characterized in that: The controllable suspension control parameters are determined as follows: Combined with road surface information and vehicle speed, the vehicle dynamics performance requirements under different driving conditions are determined, and a comprehensive performance evaluation function is designed to characterize the dynamics performance of different vehicles. The comprehensive performance evaluation function considers both vehicle ride comfort and handling stability. Taking the comprehensive performance evaluation function P as the fitness function, an optimization algorithm is used to find the optimal solution and obtain the suspension control parameters under different vehicle dynamic performance requirements.

16. The control method according to claim 15, characterized in that: The expression of the comprehensive performance evaluation function P is: Where w1 and w2 are the weight coefficients of ride comfort and handling stability respectively. and rms(F d ) are the average values ​​of the weighted acceleration of the vehicle body center of mass and the root mean square value of the dynamic loads on the four wheels, and rms(F df ) are the relevant values ​​of the reference passive suspension.

17. The control method according to claim 15, characterized in that: The vehicle dynamics performance requirements under different driving conditions are specifically as follows: when the vehicle is traveling at a speed greater than or equal to 90 km / h, the vehicle dynamics performance requirement is handling stability; when the vehicle is traveling at a speed less than 30 km / h, the vehicle dynamics performance requirement is ride comfort.

18. The control method according to claim 11, characterized in that: The control strategy includes a model predictive control strategy, a linear quadratic optimal control strategy or an improved skyhook control strategy.

19. The control method according to claim 11, characterized in that: Vehicle dynamics performance requirements take precedence over comfort requirements.

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