Active suspension vehicle and method of controlling the same

Abstract

The present application discloses an active suspension vehicle and its control method. Each wheel of the active suspension vehicle is equipped with an active actuator with telescopic adjustment function. The control method firstly constructs a load and deformation combined control matrix of the vehicle and measures the current vehicle state parameters; determines the vertical displacement excitation that each wheel will bear at the next moment from the current moment by the front road preview system, and solves the passive response of the vehicle height and attitude and the wheel load at the next moment; determines the vehicle height and attitude and the feasible wheel load expectation at the same moment, and reversely solves the active adjustment amount of the suspension when the vehicle runs to the vertical displacement excitation; finally, the vehicle in running is made to real-time pursue the vehicle height and attitude and the feasible wheel load expectation through active adjustment. The present application can implement the synchronous and active control of the vehicle height and attitude and the wheel load distribution during the running of the vehicle with any number of axles, and significantly improves the passability, maneuverability and stability of the vehicle under complex road surface.

Description

Technical Field

[0001] The present invention belongs to the technical field of active suspension, and in particular to the technical field of active suspension for multi-axle vehicles traveling on complex roads. Background Art

[0002] Active suspension systems and control methods for advanced vehicles should enable active control of vehicle height and attitude during driving. Multi-axle vehicles (including any number of axles, two or more) with extensive off-road driving requirements, including passenger off-road vehicles, medium- and heavy-duty commercial vehicles, and military wheeled vehicles, face a pressing need for active vehicle height adjustment, as well as active pitch and roll adjustment, when navigating extreme terrain such as slopes, potholes, and rocky debris. However, as statically indeterminate or even highly indeterminate systems, active vehicle height and attitude control can easily lead to unsatisfactory wheel load distribution, or even individual wheels becoming suspended or overloaded. This can result in insufficient adhesion and traction during off-road driving, causing severe vehicle body oscillations and severely impacting the vehicle's maneuverability, maneuverability, and stability. Simultaneously implementing active control of vehicle height, attitude, and wheel loads while navigating complex roads is crucial for significantly improving vehicle maneuverability, maneuverability, and stability.

[0003] For example, CN110901325A discloses an active suspension control method. During vehicle driving, the road ahead is observed to obtain a road unevenness curve, and the vehicle's own posture that should be maintained to achieve smoothness on the road surface is estimated to obtain an expected value of the vehicle body posture; the active suspension controller calculates compensation information based on the road unevenness curve, and calculates the suspension adjustment instruction based on the current vehicle posture; when the vehicle drives to the uneven road surface, the active suspension controller sends a suspension adjustment instruction to the chassis controller; the chassis controller controls the actuating mechanisms of each suspension to independently adjust the corresponding suspension, so that the vehicle can adapt to changes in road surface roughness, maintain good vehicle smoothness, and improve vehicle ride comfort.

[0004] In addition, US2019 / 0359025Al discloses another active suspension control system and control method. The suspension obtains vehicle and road characteristics through sensors, detects the pitch and roll state of the vehicle, and determines whether the vehicle exceeds the horizontal threshold; when the vehicle exceeds the horizontal threshold, the electronic controller controls the pressure in the adjustable suspension spring cavity to achieve horizontal control of the vehicle and correct the pitch and roll of the vehicle. When the vehicle is in a horizontal state, the pressure sensor is used to detect whether the pressure in the adjustable suspension spring cavity exceeds the threshold, and determines whether it is necessary to adjust the pressure in each cavity to make the pressure in each tire basically equal. It is worth noting that the horizontal control and pressure balance control of this control system act alternately, and it is impossible to perform synchronous control of the vehicle posture and wheel load.

[0005] It can be seen that the current active suspension system and its control method mainly focus on the active control of vehicle height and posture, and have a certain ability to improve driving stability. However, current technology has not yet been able to achieve the synchronous and active control of vehicle height and posture and wheel load, especially the synchronous and active control of vehicle height and posture and wheel load under complex road conditions of multi-axle vehicles. The core difficulty lies in that the active control of vehicle suspension is an over-determined problem, and the degree of over-determination gradually increases with the number of axles. The lifting and lowering actuation of the active actuator associated with any wheel will cause the vehicle height and posture to change, and at the same time cause the load on all wheels to be redistributed. The more axles there are, the more complex the control difficulty. In view of this, the present invention proposes an active suspension system and its control method that can achieve synchronous and active control of vehicle height and posture and wheel load distribution, so as to realize flexible and universal active suspension control on the road for vehicles with any number of axles, and break through the bottleneck of the passability, maneuverability and stability of vehicles with any number of axles in non-road environments. Summary of the Invention

[0006] This invention proposes an active suspension vehicle and control method capable of synchronized and active control of vehicle height, posture, and wheel load distribution for vehicles with any number of axles. Each wheel of this active suspension vehicle is equipped with an active actuator with telescopic adjustment capabilities. This active actuator is then actively adjusted during driving to ensure that the vehicle's height and posture track the desired height and posture in real time when navigating complex roads. Simultaneously, the wheel load distribution tracks the desired feasible wheel load. This control method, based on the accurate characterization of the vehicle's inherent load-bearing and deformation coupling properties, first proactively calculates the passive response of the vehicle height, posture, and wheel load at the next moment in driving. It then determines the desired vehicle height, posture, and feasible wheel load at that moment. It then reversely calculates the active suspension adjustment required to achieve the desired height, posture, and feasible wheel load when the vehicle encounters the corresponding road surface features at that moment. Finally, vehicle driving and active suspension adjustment are synchronized. Ideally, a vehicle with any number of axles can synchronize the desired height, posture, and feasible wheel load when navigating complex roads, significantly improving the vehicle's maneuverability, maneuverability, and stability on complex roads.

[0007] One aspect of the present invention is that the number of axles of the active suspension vehicle can be two or more than two axles, the wheels and axles of the active suspension vehicle are connected to the vehicle body through an active suspension system, and each of the wheels is equipped with an active actuator of the active suspension system, the active actuators have a telescopic adjustment function and are respectively assigned serial numbers 1 to n.

[0008] The sensing system, serving as the input to the control system, primarily includes a vehicle state measurement system, a forward-path preview system, a vehicle speed measurement system, and a travel measurement system. The vehicle state measurement system is equipped with an attitude sensor that measures the vehicle's roll, pitch, and yaw angles, as well as their corresponding accelerations; a force sensor that measures the vertical support load of each active actuator, defining the wheel load as a function of the vertical support load; and a displacement sensor that measures the telescopic displacement of each active actuator, defining the vehicle height as a function of the telescopic displacement. The forward-path preview system is equipped with sensors that measure the road surface topography from a longitudinal distance of at least one vehicle length in front of the wheels of the first axle, within a horizontal viewing angle of at least 120° longitudinally in front of the vehicle. The vehicle speed measurement system is equipped with wheel speed sensors mounted on both wheels of the first and last axles, coordinated with corresponding force sensors on each wheel. The system determines whether the corresponding wheel is slipping unloaded based on the signals from the force sensors, and then determines the vehicle's travel speed based on the wheel speeds of the non-unloaded wheels. It's worth noting that the current configuration of wheel speed sensors in the vehicle speed measurement system represents only a minimum configuration. As the number of axles increases, additional wheel speed sensors can be added to accurately determine vehicle speed. The driving measurement system is equipped with sensors that measure driver inputs, such as the steering wheel, accelerator, and brake pedal. It combines the vehicle state and motion parameters measured by the vehicle state measurement system and the vehicle speed measurement system to determine future driving and steering parameters. The relationship between the future travel path and travel time of each wheel of the active suspension vehicle is jointly planned and determined by the vehicle state measurement system, the forward road prediction system, the vehicle speed measurement system, and the driving measurement system. The future vertical displacement excitation of each wheel is defined as a data array of road surface topography and travel time along the future travel path. The future vehicle height, posture, and wheel load distribution expectations for the active suspension vehicle are predefined data arrays adapted to the future travel path's topography. The control system determines the expected future vehicle height, posture, and wheel load distribution based on the road surface topography and travel time along the future travel path, as well as the vehicle's current height, posture, and wheel loads. It is worth noting that the sensing system is not limited to the configuration described herein, and any apparatus and method for obtaining the required signal in any manner should be included within the scope of the claims.

[0009] The active suspension system serves as the output of the control system. The control system determines the telescopic adjustment of the active actuator by invoking the control method. During driving, the active actuator is actively adjusted to ensure that the vehicle's height and posture align with the desired height and posture as it traverses the future path. Simultaneously, the wheel load distribution synchronizes and tracks the desired desired wheel load in real time. It is worth noting that there are no restrictions on the type of active actuator; it can be driven by a fluid system or an electromechanical system. When driven by a fluid system, the fluid can be either hydraulic fluid or compressed gas.

[0010] Another aspect of the present invention is to provide an active control method for a suspension system, wherein the control method uses the center of mass of the vehicle body as the origin of the coordinate system, the x-axis is parallel to the ground and points in the direction of vehicle travel, the z-axis points vertically upward, and the y-axis points to the left of the driver, and the longitudinal and transverse coordinates of each wheel are recorded as (x i ,y i ), i=1, 2, ... n, the sequence of the wheel numbers is consistent with the sequence of the active actuators, and the total weight of the vehicle body is recorded as G. The specific steps of the control method are as follows:

[0011] First, the active suspension vehicle is driven on a level, smooth road surface to actively extend the i-th active actuator, which is measured in real time by the corresponding displacement sensor until a unit displacement is generated. During this period, the other active actuators remain inactively adjusted. The force sensor measures the incremental load on each wheel, and the incremental wheel loads are stored sequentially in the i-th column, rows 1 to n, of a matrix, in order from 1 to n. The unit displacement range is 1% to 5% of the maximum travel of the active actuator.

[0012] At the same time, the attitude sensor measures the roll angle and pitch angle increments of the vehicle body, and stores the increments in the n+1th to n+2th rows of the i-th column of the matrix in order from top to bottom.

[0013] Drive each active actuator in turn and perform the above measurements and data storage until the load-bearing and deformation joint control matrix is ​​constructed:

[0014]

[0015] Secondly, the attitude sensor measures the roll angle of the vehicle body at the current moment and pitch angle The force sensor is used to measure the wheel load of each wheel at the current moment, and the wheel load array at the current moment is constructed.

[0016] Secondly, the vertical displacement excitation array [d1…d i … d n ] T , and calculate the average value of the vertical displacement excitation array The value of the unit time interval between the current moment and the next moment is determined by the control system based on the complexity of the road surface features on the future driving path.

[0017] Secondly, based on the load and deformation joint control matrix, the roll angle, pitch angle, wheel load array at the current moment, and the vertical displacement excitation array, the passive response advance solution equation of the vehicle posture and wheel load without active control is constructed.

[0018]

[0019] In formula (2), F i v is the load that each wheel will bear when it drives onto the topographical feature of the vertical displacement excitation array at the next moment, obtained by advance calculation, i = 1, 2, ... n, is the roll angle and pitch angle of the vehicle body at the next moment obtained by advance calculation, j = x, y, the average value is the vehicle height increment that the vehicle body will generate at the next moment;

[0020] Secondly, the control system determines the expected vehicle height and expected vehicle posture when the vehicle travels onto the topographical features of the vertical displacement excitation array at the next moment based on the expected future vehicle height and posture;

[0021] At the same time, the load distribution expectation F at the next moment is given i s , i=1,2,...n, and the feasible wheel load expectation is determined by the following steps: First, the wheel load F i and the load distribution expectation F i s The optimization goal is to minimize the mean square error, and the mechanical equilibrium condition is used as a constraint to solve the expected initial value of the wheel load F i *1 ,i=1,2,...n。Since this method takes the minimum mean square error of all wheel loads as the optimization target, the result obtained by the solution may not be the global optimal solution for some special wheel load distribution expectations, so it is further optimized. Therefore, with the wheel load expectation initial value F i *1 To optimize the initial value, the effective optimization range of the wheel load is set, and then the mechanical equilibrium condition is used as a constraint to continue the optimization solution to obtain the feasible wheel load expectation F when the vehicle travels to the topographical feature of the vertical displacement excitation array at the next moment. i * , i=1,2,...n.

[0022] Secondly, based on the load-deformation joint control matrix, the passive response of the vehicle posture and wheel load, the desired vehicle posture and the desired feasible wheel load, the inverse solution equation for active suspension adjustment is constructed:

[0023]

[0024] In formula (3), is the desired vehicle posture, j = x, y.

[0025] Secondly, solve formula (3) to obtain the suspension active adjustment basic array [a1 … a i … a n ] T , and calculate its average Subtract the average value from the active suspension adjustment base array and compensate for the vehicle height expectation a h ,get

[0026]

[0027] Secondly, solve formula (4) to obtain the suspension active adjustment correction array that achieves the desired vehicle height, vehicle posture and feasible wheel load when the active suspension vehicle drives onto the topographical features of the vertical displacement excitation array at the next moment:

[0028] Finally, the control system controls the active suspension vehicle to travel to the topographical features of the vertical displacement excitation array at the next moment, and at the same time controls the active actuator to perform active telescopic adjustment, and synchronously completes the actuation adjustment of the suspension active adjustment correction array at the next moment, that is, completes the synchronous and active control of the vehicle height, vehicle posture and wheel load distribution within a unit time interval.

[0029] The beneficial effects of the present invention are as follows:

[0030] 1. For vehicles with two or more axles, this active suspension vehicle and its control method enable synchronized, active control of vehicle height, posture, and wheel load distribution. On complex road surfaces, this ensures that vehicle height and posture track the target height and posture in real time while simultaneously ensuring that wheel loads reach the desired feasible wheel load. This reduces vehicle height and posture disturbances caused by contact support reaction forces and maximizes traction. This provides a flexible, efficient, stable, and safe suspension control method for vehicles navigating complex road surfaces, significantly improving the trafficability, maneuverability, and stability of vehicles with any number of axles.

[0031] 2. This active suspension vehicle and its control method, based on the accurate characterization of the vehicle's inherent load-bearing and deformation coupling properties, constructs an advance solution equation for the passive response from the current moment to the next moment and an inverse solution equation for the active suspension adjustment under the target expectation. This allows for rapid and reliable accurate calculation of the active suspension adjustment amount, and in principle provides an active control methodology that can achieve the target expectation of vehicle height, posture, and wheel load distribution simultaneously without iteration. This solution effectively avoids the shortcomings of current control schemes, which repeatedly measure vehicle height, posture, and wheel load distribution errors, and then cyclically judge and iteratively control, resulting in time-consuming, oscillating, and even inability to converge to the target expectation. At the same time, this solution does not require the huge perception, computing power, and response speed requirements required for artificial intelligence control; it is a cost-effective, efficient, and reliable control method. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A flow chart of a control method for an active suspension vehicle and a control method thereof according to the present invention;

[0033] Figure 2 A schematic diagram of the structure principle of an active suspension vehicle and a control method thereof according to the present invention;

[0034] 3 is a schematic diagram of the adjustment process of the vehicle height, vehicle posture and wheel load when the right front wheel of the active suspension vehicle of the present invention steps onto the boss. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. Figure 2 , the execution system, sensing system and control system of the three-axle independent active suspension vehicle shown in 3, and Figure 1 The control method flow chart shown in the figure provides a specific description of the active suspension vehicle and its control method. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not limited to the specific implementations of the actuator system, sensing system, and control system employed in the specific embodiments.

[0036] like Figure 2As shown in Figure 3, the wheels 1 and axles 2 of the active suspension vehicle are connected to the vehicle body 3 through the active suspension system 15. The sensing system 14 and the active suspension system 15 are the input and output ends of the control system 16 respectively. The number of axle shafts of the active suspension vehicle can be two or more, and each of the wheels 1 is equipped with an active actuator 13 of the active suspension system 15. The active actuators 13 have telescopic adjustment functions and are assigned serial numbers 1 to n respectively. The sensing system 14 includes a vehicle state measurement system 14a, a front road preview system 14b, a vehicle speed measurement system 14c, and a driving measurement system 14d. Those skilled in the art should realize that the active actuator 13 can be driven by a fluid system or an electromechanical system. When driven by a fluid system, the fluid can be any one of a hydraulic fluid and a compressed gas. Therefore, Figure 2 The embodiment shown is merely one embodiment in which the fluid sealing chamber 13 b and the electromagnetic reversing valve group 13 a are used as the active actuator 13 .

[0037] The vehicle body state measurement system 14a is equipped with a posture sensor 10 for measuring the roll angle, pitch angle, yaw angle, and corresponding acceleration of the vehicle body 3; a force sensor 11 for measuring the vertical support load of each active actuator 13, and defining the wheel load as a function of the vertical support load; and a displacement sensor 12 for measuring the telescopic displacement of each active actuator 13, and defining the vehicle body height as a function of the telescopic displacement. Those skilled in the art should appreciate that the force sensor 11, displacement sensor 12, and posture sensor 10 included in the vehicle body state measurement system 14a are limited to the configuration of this embodiment. There are various configurations and methods for obtaining the vehicle body state parameters obtained by the vehicle body state measurement system 14a, and these different configurations and methods are also within the scope of the present invention.

[0038] The forward road preview system 14b is equipped with sensors that measure road surface topography characteristics within a horizontal viewing angle of at least 120° longitudinally in front of the vehicle, extending from a distance in front of the wheels of the first axle to at least one vehicle length. Those skilled in the art will appreciate that the forward road preview system 14b can be implemented in a variety of different combinations, such as using a laser radar to scan a point cloud array of the road ahead, or using machine vision methods to acquire road surface topography characteristics. These different combinations of methods are also intended to be within the scope of the present invention.

[0039] The vehicle speed measurement system 14c is equipped with wheel speed sensors 17 mounted on the wheels on both sides of the first and last axles, and cooperates with the corresponding force sensors 11 on each wheel. The system determines whether the corresponding wheel is slipping without load based on the signals from the force sensors 11, and then determines the vehicle speed based on the speed of the non-unloaded wheels. Those skilled in the art will appreciate that the current configuration of wheel speed sensors 17 in the vehicle speed measurement system is only the minimum configuration, and that as the number of axles increases, more wheel speed sensors 17 can be added to accurately determine the vehicle speed.

[0040] The driving measurement system 14d is equipped with sensors that measure steering, accelerator, and brake inputs, and combines the vehicle state and motion parameters measured by the vehicle state measurement system 14a and vehicle speed measurement system 14c to determine future driving and steering parameters. Those skilled in the art will appreciate that the driving measurement system 14d is used to obtain vehicle state and motion parameters such as wheel angles and steering wheel angles, and the present invention is not limited to the methods used to obtain these parameters. For example, different methods for obtaining wheel angles and steering wheel angles, such as direct measurement using an inclination sensor or calculation based on motion parameters, are all within the scope of the present invention.

[0041] The relationship between the future passing path and passing time of each wheel of the active suspension vehicle is jointly planned and determined by the vehicle body state measurement system 14a, the front road preview system 14b, the vehicle speed measurement system 14c, and the driving measurement system 14d, and the future vertical displacement excitation of each wheel is defined as a data array of the road surface morphology characteristics and passing time on the future passing path.

[0042] The future vehicle height, posture and wheel load distribution expectations of the active suspension vehicle are predefined data arrays adapted to the topographical features of the future driving path, and are determined by the control system 16 based on the road surface topography and driving time on the future driving path, as well as the vehicle height, posture and wheel load of the vehicle body 3 at the current moment.

[0043] Based on the hardware configuration of the above active suspension vehicle, the control system 16 will call the control method to determine the telescopic adjustment amount of the active actuator 13, and implement active telescopic adjustment on the active actuator 13 during driving so as to achieve the vehicle height and posture chasing the desired vehicle height and posture when the vehicle actually passes through the future driving path. At the same time, the wheel load distribution of each wheel is synchronized and chases the feasible wheel load expectation in real time. In order to explain the control method, the center of mass of the vehicle body 3 is used as the origin of the coordinate system, the x-axis is parallel to the ground and points to the direction of vehicle travel, the z-axis points vertically upward, and the y-axis points to the left of the driver to define the coordinate system. The longitudinal and transverse coordinates of each wheel are recorded as (x i ,y i), i=1, 2, ... n, the sequence of the wheels is consistent with the sequence of the active actuators 13, the total weight of the vehicle body 3 is denoted as G, and the specific steps include:

[0044] Step 101: Construct a load-bearing interaction matrix. The control system 16 is used to drive the i-th fluid sealing chamber 13b to vertically extend, with the displacement sensor 12 measuring this in real time until a unit displacement is generated. During this period, other active actuators are kept inactive. The force sensor 11 measures the pressure value of each fluid circuit in each fluid sealing chamber 13b. The absolute value of the fluid circuit load difference is calculated to obtain the wheel load increment. Each load increment is divided by the unit displacement in order from 1 to n and placed sequentially in the i-th column, rows 1 to n of an n×n dimensional matrix. Each fluid sealing chamber 13b is driven cyclically and the load increment of each fluid sealing chamber 13b is measured, thereby completing the construction of the load-bearing interaction matrix shown below:

[0045]

[0046] The unit displacement is 1% to 5% of the maximum actuating stroke of the fluid sealing cavity 13b.

[0047] Step 102: Construct a deformation interaction matrix. While the control system 16 drives the i-th fluid sealing chamber 13b to generate the unit displacement, the attitude sensor 10 in the vehicle state measurement system 14a measures the vehicle body's inclination increments around the x-axis and y-axis, respectively. Each inclination increment is divided by the unit displacement and placed into the first and second rows of the i-th column of a 2×n-dimensional matrix, completing the construction of the deformation interaction matrix shown below:

[0048]

[0049] Step 103: Construct the joint load-bearing and deformation control matrix. Input the load-bearing interaction matrix obtained in step 101 to the first to nth rows of the (n+2)×n-dimensional matrix; input the deformation interaction matrix obtained in step 102 to the last two rows of the (n+2)×n-dimensional matrix, completing the construction of the joint load-bearing and deformation control matrix as shown below:

[0050]

[0051] Step 104: Measure the current wheel load. Use the force sensor 11 to measure the pressure of each fluid circuit in each fluid sealing cavity 13b, and then calculate the absolute value of the fluid circuit load difference based on the area of ​​the rod cavity and the rodless cavity in the fluid sealing cavity 13b, and then calculate the current load F of the corresponding wheel. i c :

[0052] F i c =|P1S1-P2S2| (4),

[0053] In formula (4), P1 is the fluid line pressure of the rod chamber, S1 is the area of ​​the rod chamber, P2 is the fluid line pressure of the rodless chamber, and S2 is the area of ​​the rodless chamber.

[0054] Step 105: Use the attitude sensor 10 to measure the roll angle of the vehicle body 3 at the current moment. and pitch angle

[0055] Step 106 , using the front road preview system 14 b , obtains road surface features in a longitudinal distance of at least one vehicle length in front of the first axle wheel and within a horizontal viewing angle of at least 120° in the longitudinal direction of the vehicle.

[0056] Step 107 , detecting the driver's inputs such as the accelerator, brake, and steering wheel angle.

[0057] Step 108 : Acquire the vehicle state and motion parameters using the vehicle state measurement system 14 a , the vehicle speed measurement system 14 c , and the travel measurement system 14 d .

[0058] Step 109 plans the vehicle's future path based on the road surface morphology characteristics obtained in step 106, the driver input detected in step 107, and the vehicle body state and motion parameters obtained in step 108, and defines the future vertical displacement excitation of each wheel as a data array of the road surface morphology characteristics and driving time on the future path.

[0059] Step 110, taking the current moment as the starting point, setting a unit time interval, and picking up the vertical displacement excitation array [d1…d2] that each wheel will be subjected to after the unit time interval at the current moment from the future vertical displacement excitation data array of each wheel described in step 109. i … d n ] T , and calculate the average value of the vertical displacement excitation array

[0060] The value of the unit time interval is determined by the control system 16 based on the complexity of the road surface features on the future driving path.

[0061] Step 111: Construct the passive response advance solution equation of vehicle posture and wheel load. Based on the load and deformation joint control matrix obtained in step 103, the current wheel load obtained in step 104, the roll angle and pitch angle of the vehicle body at the current moment obtained in step 105, and the vertical displacement excitation array obtained in step 110, construct the passive response advance solution equation of vehicle posture and wheel load without active control.

[0062]

[0063] Step 112: Preemptively solve the passive response of vehicle height, vehicle posture, and wheel load. Solve the passive response preemptive solution equation constructed in step 111 to obtain the vehicle height, vehicle posture, and wheel load when the vehicle travels to the topographical feature of the vertical displacement excitation array at the next moment. In formula 5, F i v is the load that each wheel will bear when it drives onto the topographical feature of the vertical displacement excitation array at the next moment, obtained by advance calculation, i=1, 2, ...n; is the roll angle and pitch angle that the vehicle body 3 will generate when it drives onto the topographical feature of the vertical displacement excitation array at the next moment, obtained by advance calculation, j = x, y; the average value of the vertical displacement excitation array in step 110 It is the vehicle height increment that will be generated when the vehicle body 3 drives onto the topographical feature of the vertical displacement excitation array at the next moment.

[0064] Step 113: Determine the desired vehicle height and posture, and calculate the feasible wheel load expectation. The control system 16 predefines the desired vehicle height and posture for the active suspension vehicle in the future based on the road surface topography and travel time determined in step 109. The desired vehicle height and posture can be set according to different actual needs. At the same time, the control system also predefines the wheel load distribution expectation F that adapts to the road surface topography on the future travel path. i s , and the feasible load expectation is determined by the following steps:

[0065] First, the wheel load F i and the load distribution expectation F i s The optimization goal is to minimize the mean square error of the wheel load. With the mechanical equilibrium condition as the constraint, the optimization model shown below is used to solve the expected initial value of the wheel load F. i *1

[0066]

[0067] In formula (6), F i s =F i *Mandatory wheel load expectations set for certain wheels of particular concern, is the uniform wheel load expectation for other general wheels, where p is the number of wheels with mandatory wheel load distribution. They are the vertical force balance constraint of the vehicle, and the moment balance constraints around the x-axis and the y-axis.

[0068] Solving formula (6) can obtain the expected initial value of wheel load F of each wheel: i *1 However, since this method aims to minimize the mean square error of all wheel loads, the result obtained may not be a global optimal solution for some special wheel load distribution expectations, so it needs to be further optimized. Therefore, it is also necessary to use the wheel load expectation initial value F i *1 To optimize the initial value, set the effective optimization range F of the wheel load i lb ≤F i ≤F i ub , and still subject to the mechanical equilibrium condition, the optimization algorithm is called to solve the feasible wheel load expectation F when driving to the topographic feature of the vertical displacement excitation array at the next moment i * , i=1,2,...n.

[0069] Step 114: Construct the inverse solution equation for active suspension adjustment. Based on the load-deformation joint control matrix obtained in step 103, the vehicle posture and passive response of the wheel load at the next moment obtained in step 112, and the vehicle posture and feasible wheel load expectation at the next moment obtained in step 113, construct the inverse solution equation for active suspension adjustment:

[0070]

[0071] In formula (7), is the desired vehicle posture, j = x, y.

[0072] Step 115: Solve the inverse equation for active suspension adjustment constructed in step 114 to obtain the active suspension adjustment basic array [a1 … a i … a n ] T , and calculate its average

[0073] Step 116: Subtract the average value from the active suspension adjustment basic array And compensate the vehicle height expectation a described in step 113 h , get the active adjustment amount of the suspension, satisfying

[0074]

[0075] Solving formula (8) can obtain the suspension active adjustment correction array that achieves the desired vehicle height, vehicle posture and feasible wheel load when the active suspension vehicle drives onto the topographical features of the vertical displacement excitation array at the next moment:

[0076] Step 117: Active suspension adjustment is performed. The control system 16 controls the active suspension vehicle to move onto the topographical features of the vertical displacement excitation array at the next moment, and simultaneously controls the active actuator 13 to perform active telescopic adjustment. This synchronizes the actuation of the active suspension adjustment correction array at the next moment, thereby achieving synchronous and active control of vehicle height, posture, and wheel load distribution within the unit time interval.

[0077] In step 118, the driver makes a subjective decision, or the controller determines based on the road surface characteristics whether the vehicle has passed the complex road surface. If so, the active control ends; if not, the process returns to steps 104, 105, 106, 107, and 108, and the active adjustment amount of the suspension is recalculated, and loop control is executed until the complex road surface is passed.

[0078] More intuitively, the following takes the case of the right front wheel of a three-axle vehicle lifting and stepping onto the boss 4 as an example to illustrate the specific implementation of the control method:

[0079] First, the front preview system 14b scans the features of the boss 4 as shown in FIG. Figure 3a As shown. For this type of small boss, assuming the control system plans to have the right front wheel step onto boss 4 without load at the next moment, and to maintain load balance on the other five wheels as the wheel load distribution expectation, and to maintain stable vehicle height and posture as the vehicle height and posture expectation. Then the vertical displacement excitation array that each wheel will experience at the next moment is {d, 0, 0, 0, 0, 0} T , d is the height of the vertical displacement excitation acting on the right front wheel. The vehicle body state measurement system 14a measures the vehicle body height and roll angle at the current moment. and pitch angle Wheel load array According to the passive response advance calculation equation of vehicle posture and wheel load, the vehicle can advance to solve the passive stepping onto the boss 4 when the right front wheel moves to the vehicle. Figure 3b The passive response of the vehicle posture and wheel load in the state shown satisfies

[0080]

[0081] Then, if the vehicle posture is expected to be stable, then The wheel load distribution expectation is that the right front wheel steps onto the boss 4 without load and the loads of the other five wheels are kept balanced. Then the wheel load distribution expectation F i * ={0,G / 5,G / 5,G / 5,G / 5,G / 5} T Substituting the passive response of vehicle body posture and wheel load, vehicle posture and wheel load distribution expectation into the suspension active adjustment inverse solution equation, the active adjustment amount of each suspension with vehicle posture and wheel load distribution expectation as the target can be calculated when the right front wheel of the vehicle steps onto the boss 4. i}:

[0082]

[0083] Again, calculate the active adjustment amount {a i The average value of If the vehicle height is kept stable as the vehicle height expectation, then a h =0, after correction, the suspension active adjustment correction array can be obtained

[0084] Finally, based on the calculated suspension active adjustment correction array, the control system 16 controls the active suspension vehicle to step onto the boss 4 at the next moment, and simultaneously controls the active actuator 13 to perform active telescopic adjustment, synchronously completing the actuation adjustment of the suspension active adjustment correction array at the next moment, that is, completing the synchronous and active control of vehicle height, vehicle posture and wheel load distribution within a unit time interval. Figure 3c As shown, when the vehicle steps onto the boss 4 , the vehicle height remains stable and the right front wheel is unloaded when stepping onto the boss 4 , and the loads on the other five wheels remain balanced.

[0085] Finally, it should be noted that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the scope of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for controlling an active suspension vehicle, wherein the wheels and axles of the active suspension vehicle are connected to the vehicle body via an active suspension system, wherein a sensing system and the active suspension system serve as the input and output of the control system, respectively. Each wheel is equipped with an active actuator of the active suspension system, wherein the active actuator has a telescopic adjustment function, and wherein: The number of axles of the active suspension vehicle is two or more; The active actuator is driven by a fluid system or an electromechanical system; when driven by a fluid system, the fluid is any one of hydraulic fluid and compressed gas; The control system determines the extension and contraction adjustment amount of the active actuator, and the active actuator is actively extended and contracted during driving so that the vehicle's height and posture track the desired vehicle height and posture in real time as the vehicle passes through the future path. At the same time, the wheel load distribution of each wheel is synchronized and tracks the feasible wheel load in real time. The coordinate system in the control method is defined with the center of mass of the vehicle body as the origin, the x-axis parallel to the ground pointing to the direction of vehicle travel, the z-axis pointing vertically upward, and the y-axis pointing to the left of the driver. The longitudinal and transverse coordinates of each wheel are recorded as (x i ,y i ), i=1, 2, ... n, each wheel corresponds to the active actuator respectively, the total weight of the vehicle body is recorded as G, and the control method includes the following steps: First, the active suspension vehicle is driven on a level, good road surface to actively extend the i-th active actuator, which is measured in real time by the corresponding displacement sensor until a unit displacement is generated. During this period, the other active actuators are kept inactive. The force sensor measures the increment of each wheel load, and the increments of the wheel loads are stored in the i-th column, rows 1 to n, in the order from 1 to n. At the same time, the attitude sensor measures the roll and pitch angle increments of the vehicle body, and stores the increments in the n+1 to n+2 rows of the i-th column of the matrix in order from top to bottom; each active actuator is driven in turn and performs the above measurement and data storage until the load-bearing and deformation joint control matrix is ​​constructed, as follows Secondly, the attitude sensor measures the roll angle of the vehicle body at the current moment and pitch angle The force sensor is used to measure the wheel load of each wheel at the current moment, and the wheel load array at the current moment is constructed. Secondly, the vertical displacement excitation array [d1…d i … d n ] T , and calculate the average value of the vertical displacement excitation array Secondly, based on the load and deformation joint control matrix, the roll angle, pitch angle, wheel load array at the current moment, and the vertical displacement excitation array, the passive response advance solution equation of the vehicle posture and wheel load without active control is constructed. In formula (2), F i v is the load that each wheel will bear when it drives onto the topographical feature of the vertical displacement excitation array at the next moment, obtained by advance calculation, i = 1, 2, ... n, is the roll angle and pitch angle of the vehicle body at the next moment obtained by advance calculation, j = x, y, the average value is the vehicle height increment that the vehicle body will generate at the next moment; Secondly, the control system determines the expected vehicle height and expected vehicle posture when the vehicle travels onto the topographical features of the vertical displacement excitation array at the next moment based on the expected future vehicle height and posture; At the same time, the load distribution expectation F at the next moment is given i s , i=1,2,...n, and the feasible wheel load expectation is determined by the following steps: First, the wheel load F i and the load distribution expectation F i s The optimization goal is to minimize the mean square error, and the mechanical equilibrium condition is used as a constraint to solve the expected initial value of the wheel load. i=1,2,...n;Then, the wheel load expected initial value In order to optimize the initial value, the effective optimization range of the wheel load is set, and then the mechanical equilibrium condition is used as a constraint to continue the optimization solution to obtain the feasible wheel load expectation when the vehicle travels to the topographical feature of the vertical displacement excitation array at the next moment. i=1,2,...n; Secondly, based on the load-deformation joint control matrix, the passive response of the vehicle posture and wheel load, the desired vehicle posture and the desired feasible wheel load, the inverse solution equation for active suspension adjustment is constructed: In formula (3), is the desired vehicle posture, j = x, y; Secondly, solve formula (3) to obtain the suspension active adjustment basic array [a1 … a i … a n ] T , and calculate its average Subtract the average value from the active suspension adjustment base array and compensate for the vehicle height expectation a h ,get Secondly, solve formula (4) to obtain the suspension active adjustment correction array that achieves the desired vehicle height, vehicle posture and feasible wheel load when the active suspension vehicle drives onto the topographical features of the vertical displacement excitation array at the next moment: Finally, the control system controls the active suspension vehicle to travel to the topographical features of the vertical displacement excitation array at the next moment, and at the same time controls the active actuator to perform active telescopic adjustment, and synchronously completes the actuation adjustment of the suspension active adjustment correction array at the next moment, that is, completes the synchronous and active control of the vehicle height, vehicle posture and wheel load distribution within a unit time interval.

2. The control method according to claim 1, characterized in that The sensing system includes a vehicle state measurement system, a road preview system, a vehicle speed measurement system, and a driving measurement system; the vehicle state measurement system is equipped with an attitude sensor for measuring the vehicle body roll angle, pitch angle, yaw angle and their corresponding accelerations, a force sensor for measuring the vertical support load of each active actuator, and defining the wheel load as a function of the vertical support load, and a displacement sensor for measuring the telescopic displacement of each active actuator, and defining the vehicle body height as a function of the telescopic displacement; The forward road preview system is equipped with a sensor for measuring the longitudinal distance in front of the wheels of the first axle up to at least one vehicle length and the road surface topography within a horizontal viewing angle of at least 120° in the longitudinal direction of the vehicle; The vehicle speed measurement system is configured with wheel speed sensors installed on the wheels on both sides of the first and last axles, and cooperates with the corresponding force sensors on each wheel. The system determines whether the corresponding wheel is slipping without load based on the signal from the force sensors, and then determines the driving speed based on the wheel speed of the non-unloaded wheel. The wheel speed sensors currently configured in the vehicle speed measurement system are only the minimum configuration. As the number of axles increases, more wheel speed sensors can be configured to accurately determine the driving speed. The driving measurement system is equipped with sensors that measure driver inputs such as steering, accelerator and brake, and combines the vehicle state and motion parameters measured by the vehicle state measurement system and vehicle speed measurement system to determine future driving and steering parameters; The relationship between the future passing path and passing time of each wheel of the active suspension vehicle is jointly planned and determined by the vehicle body state measurement system, the front road preview system, the vehicle speed measurement system, and the driving measurement system, and the future vertical displacement excitation of each wheel is defined as a data array of the road surface topography characteristics and passing time on the future passing path.

3. The control method according to claim 1, wherein: The unit displacement ranges from 1% to 5% of the maximum actuating stroke of the active actuator.

4. The control method according to claim 1, wherein: The value of the unit time interval between the current moment and the next moment is determined by the control system based on the complexity of the road surface features on the future driving path.

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