Active suspension control system and control method for off-road multi-axle vehicles

Abstract

The application discloses a non-road multi-axle vehicle active suspension control system and a control method. The active suspension of the vehicle adopts a double wishbone independent suspension structure, and an active actuator with telescopic adjustment function and a shock absorber connected in series are arranged for each wheel. The active suspension control system calls the active suspension control method, first outputs the current wheel, suspension, vehicle body posture and wheel load data of the vehicle in the display screen, then according to the input of the driver through the pitch, roll and height adjustment switches, calculates the telescopic adjustment amount required by each active actuator to achieve the control expectation, and drives each active actuator to synchronously implement active control, and the display screen updates the current posture and wheel load data of the vehicle in real time until the active control is completed. The application can provide flexible and effective vehicle height and posture active control and intuitive man-machine interaction function for the low-speed passing of the multi-axle active suspension vehicle through extreme terrain, and improves the passability and stability of the non-road multi-axle vehicle.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of active suspension, and particularly relates to the technical field of active control of vehicle body posture of non-road multi-axle vehicles. BACKGROUND

[0002] Non-road multi-axle (including any axle number of two axles and above) vehicles, including passenger off-road vehicles, medium / heavy commercial vehicles, military vehicles, unmanned vehicles, etc., have extensive needs for low-speed driving through longitudinal and transverse slopes, bumpy roads, rubble, and other non-road extreme terrains. During low-speed driving, the vehicle body posture often changes dramatically, some wheels are suspended, and even the vehicle is stuck and difficult to continue driving. If the current state of the vehicle can be effectively displayed during this period, and the active control of the vehicle body posture according to the driver's intention is implemented, and further the real-time active control of the vehicle body height adjustment, pitch and roll posture adjustment is implemented, it has important value for improving the passability and stability of non-road multi-axle vehicles.

[0003] Currently, the real-time calculation and display of the vehicle state of multi-axle vehicles, especially three axles or more, under non-road extreme terrains, and the active control of the vehicle body posture according to the driver's intention are still blank. The difficulties are as follows: first, multi-axle vehicles under extreme terrains face complex situations such as severe vehicle body tilting and wheel suspension, and a vehicle state testing system needs to be designed to build a real-time calculation and cabin display method of the vehicle state; in addition, an active control method of the vehicle body posture needs to be built for the driver's vehicle height adjustment, pitch and roll expectations as the target. The more the number of vehicle axles and the more complex the driving environment, the more difficult the control system and control method need to be built. In view of this, the present application proposes an active suspension control system and control method for realizing active control of vehicle height and posture in low-speed driving through extreme terrains, to realize flexible and effective human-machine interaction and active control function of vehicles with any number of axles, and break through the bottleneck of passability and stability of non-road multi-axle vehicles. SUMMARY

[0004] In view of the defects in the prior art, the purpose of the present application is to provide an active suspension control system and control method for non-road multi-axle vehicles, to solve the real-time display of the vehicle state under non-road extreme terrains and the active control function of the vehicle body height adjustment, pitch and roll posture according to the driver's intention, and to improve the passability and stability of non-road multi-axle vehicles. To achieve the above purpose, the technical solution adopted by the present application is as follows:

[0005] On the one hand, an active suspension control system for non-road multi-axle vehicles is provided, the wheels and the vehicle body of the vehicle are connected through the active suspension, the active suspension adopts a double wishbone independent suspension structure, and the control system comprises:

[0006] The number of axles of the vehicle can be any number of axles equal to or greater than 2 axles, and the number of axles is denoted as n.

[0007] The active suspension of the vehicle is configured with an active actuator with axial telescopic adjustment function for each wheel, and the active actuator is axially connected with a shock absorber, and the stiffness characteristic of the shock absorber has been calibrated;

[0008] The vehicle at least includes a displacement sensor for measuring the axial telescopic displacement of the active actuator, a force sensor for measuring the axial force, and a tilt angle sensor for measuring the pitch angle and roll angle of the vehicle body;

[0009] The vehicle cabin is configured with pitch, roll and height adjustment switches; the pitch, roll and height adjustment switches can adopt any form of lever, button, knob, or touch button provided in the display screen; the pitch, roll and height adjustment switches respectively send one or more of the pitch down or pitch up, roll left or roll right, and height up or height down instructions to the active suspension controller;

[0010] The vehicle cabin is also configured with a display screen with input and output functions; the display screen can manually modify the pitch, roll and height adjustment reference values corresponding to the pitch, roll and height adjustment switches by the driver; the internal memory of the control system pre-stores the pitch, roll and height adjustment reference values, which are 1°, 1° and 10 cm respectively;

[0011] The control system has artificially specified a number of key nodes reflecting the wheel, suspension and vehicle body posture, including but not limited to the connection points causing the relative position changes of the components, such as the wheel bottom center point and wheel contour point, the upper and lower stop points of the active suspension, the hinge points of the double wishbone, and the vehicle height reference points defined by the intersection of the vehicle body longitudinal reference line and the cross section of each active suspension, and the nodes reflecting the vehicle body contour characteristics;

[0012] The vehicle is configured with an active suspension controller; the active suspension controller stores an executable active suspension control program; when the active suspension control program is executed, the active suspension control method for off-road multi-axle vehicles is called, which first outputs the current wheel, suspension and vehicle body posture information of the vehicle in graphical and digital form in the display screen, and the wheel load information calculated according to the axial force of each active actuator; then according to the pitch, roll and height adjustment switches triggered by the driver, and the pitch, roll and height adjustment reference values, the telescopic adjustment amount required to achieve the control of each active actuator is calculated, and then each active actuator is driven to act synchronously to implement active control; at the same time, the display screen updates the current wheel, suspension and vehicle body posture information of the vehicle, and the wheel load information in real time until the active control is completed.

[0013] The second aspect also provides a method for controlling active suspension of a non-road multi-axle vehicle, based on the double-wishbone independent suspension architecture, the inclination of the vehicle body relative to the horizontal plane is consistent with the inclination of the vehicle wheels relative to the longitudinal symmetry plane of the vehicle, and the control method is based on the premise that the vehicle is currently driving in a non-road environment, and at least three wheels of the vehicle are reliably in contact with the ground; the control method comprises the following steps:

[0014] Step 1: Measure the current pitch angle and roll angle of the vehicle body by the inclination sensor;

[0015] Step 2: Determine the local coordinate function of each key node of each axle, specifically including: based on each wheel on either side of the vehicle, sequentially establish the local rectangular coordinate system of each axle from the first axle to the nth axle i x i y i z i , i = 1, 2,..., n, wherein the yz coordinate plane is parallel to the cross section of the active suspension of each axle, the x axis is perpendicular to the yz coordinate plane, pointing to the forward direction of the vehicle, the y axis is horizontal to the left, and the z axis is upward; in the local direct coordinate system of each axle, the local coordinate function of each key node of each axle is established based on the roll angle of the vehicle body and the rotation angle of the double-wishbone relative to the vehicle body;

[0016] Step 3: Determine the distance between the upper and lower stops of the active suspension on both sides of each axle, specifically including: the displacement sensor measures the axial extension displacement of each active actuator of each axle, and then determines the absolute length of each active actuator; the force sensor measures the axial force of each shock absorber of each axle, and then determines the absolute length of each shock absorber according to its stiffness characteristics; combine the two to determine the distance between the upper and lower stops of the active suspension on both sides of each axle;

[0017] Step 4: Solve the rotation angle of the double-wishbone relative to the vehicle body on both sides of each axle: for each active suspension of each axle, according to the coordinate function of the upper and lower stops of the active suspension on both sides of each axle, and the distance between the upper and lower stops, solve the rotation angle of the double-wishbone relative to the vehicle body on both sides of each axle;

[0018] Step 5: Determine the y-axis and z-axis coordinates of all key nodes in the local rectangular coordinate system: substitute the calculated rotation angle of the double-wishbone relative to the vehicle body on both sides of each axle into the local coordinate function of each key node of each axle to determine the y-axis and z-axis coordinates of all key nodes in the corresponding local rectangular coordinate system;

[0019] Step 6: determining the global coordinates of the key nodes of the axle where the global coordinate system is located, specifically comprising: establishing a global coordinate system OXYZ with the origin of the local rectangular coordinate system of any axle as the origin, with the X axis pointing horizontally forward, the Y axis horizontally left, and the Z axis vertically upward; determining the three-dimensional coordinates of the key nodes of the axle in the global coordinate system according to the pitch angle of the vehicle body measured by the tilt sensor and the y and z axis coordinates of the key nodes of the axle in the corresponding local rectangular coordinate system;

[0020] Step 7: determining the three-dimensional coordinates of the key nodes of the other axles in the global coordinate system, specifically comprising: determining the X and Z axis coordinates of the vehicle height reference points of the other axles in the global coordinate system according to the pitch angle of the vehicle body measured by the tilt sensor; setting the Y axis coordinates of the vehicle height reference points in the global coordinate system to be consistent with the Y axis coordinates of the vehicle height reference points of the axle where the global coordinate system is located in the global coordinate system; determining the y and z axis distances between the vehicle height reference points and the other key nodes of the corresponding axles according to the y and z axis coordinates of the key nodes in the corresponding local rectangular coordinate system, and then calculating the three-dimensional coordinates of all key nodes in the global coordinate system according to the three-dimensional coordinates of the vehicle height reference points in the global coordinate system;

[0021] The vehicle current wheel, suspension, body posture information and wheel load information calculated by the axial force of each active actuator are output in the display screen in the active suspension control system of the off-road multi-axle vehicle, which is realized by calling steps 1 to 7 of claim 2;

[0022] Step 8: detecting the wheel grounding condition and implementing grounding adjustment: if no, i.e. there is a wheel in the air, driving the active actuator associated with the wheel in the air to act axially until all wheels are in contact with the ground; if yes, i.e. all wheels are grounded, re-calling steps 1 to 5 to recalculate the z axis coordinates of all key nodes in the corresponding local rectangular coordinate system;

[0023] Step 9: detecting the pitch, roll and height adjustment switch instructions of the driver; picking up the reference values of the pitch, roll and height adjustment input by the driver or pre-stored in the internal memory;

[0024] Step 10: calculating the extension and retraction adjustment amount of all active actuators, specifically including: determining the z-axis coordinate of each vehicle height reference point after active control according to the pitch angle reference value, the height adjustment reference value, and the z-axis coordinate of each vehicle height reference point in the corresponding local rectangular coordinate system; setting the z-axis coordinate of each vehicle height reference point after active control to be equal to the z-axis coordinate function of the corresponding vehicle height reference point; at the same time, setting the z-axis coordinate of the center point of the bottom surface of the wheel opposite to the wheel at the origin of the local rectangular coordinate system of each vehicle axle to be equal to the z-axis coordinate function of the point; solving the rotation angle of the double wishbone on both sides of each vehicle axle relative to the vehicle body according to the above equation; substituting the rotation angle of the double wishbone on both sides of each vehicle axle relative to the vehicle body into the coordinate function of each key node of each vehicle axle to calculate the coordinates of the upper and lower stop points of the active suspension on both sides of each vehicle axle after active control, and then determine the extension and retraction adjustment amount required by all active actuators;

[0025] Step 11: controlling all active actuators to implement active extension and retraction adjustment simultaneously: the active suspension control system drives all active actuators to implement active extension and retraction adjustment simultaneously, and at the next moment, the extension and retraction adjustment amount is completed, that is, the active control of the pitch, roll and height adjustment reference values corresponding to the current trigger of the pitch, roll and height adjustment switch instructions of the driver is completed;

[0026] Step 12: cyclically detecting whether the pitch, roll and height adjustment switch instructions of the driver are stopped: if there is still a pitch, roll or height adjustment instruction, jump to the step of detecting the wheel grounding condition and implementing the grounding adjustment; if not, end the active control.

[0027] Compared with the prior art, the present application has the following advantages:

[0028] With the proposed active suspension control system as the carrier, according to the axial force and displacement data of each vehicle axle active actuator and the pitch angle and roll angle data of the vehicle body, through the proposed active suspension control method, the vehicle wheel, suspension, vehicle body posture information and wheel load information are calculated and displayed on the cabin screen in real time, so that the driver can intuitively obtain the vehicle state and provide the most real and reliable vehicle information for the next active control.

[0029] According to the pitch, roll and height adjustment instructions of the driver, the adjustment amount of the active actuator reaching the control expectation is calculated. The adjustment amount of the active actuator obtained by the control method can reach the control expectation without iteration and synchronization, avoiding the time-consuming, shock, overshoot and even adjustment failure problems existing in traditional feedback control, improving the flexibility, stability and safety of the active control of the vehicle body posture, and further improving the passability and stability of the multi-axle vehicle in the non-road extreme terrain. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings described below are only some of the embodiments of the present application, and for those skilled in the art, other drawings can also be obtained from these drawings without creative labor.

[0031] Figure 1 Flow chart of control method in the active suspension control system and control method of the off-road multi-axle vehicle of the present application.

[0032] Figure 2 Structure principle schematic diagram of the off-road multi-axle vehicle in the active suspension control system and control method of the off-road multi-axle vehicle of the present application.

[0033] Figure 3 Schematic diagram of the display screen in the active suspension control system and control method of the off-road multi-axle vehicle of the present application.

[0034] Figure 4 Connection block diagram of the control system in the active suspension control system and control method of the off-road multi-axle vehicle of the present application.

[0035] Figure 5 Schematic diagram of the coordinate system setting in the active suspension control system and control method of the off-road multi-axle vehicle of the present application.

[0036] Figure 6 Schematic diagram of the key node setting in the active suspension control system and control method of the off-road multi-axle vehicle of the present application.

[0037] Figure 7 Schematic diagram of the vehicle height reference point relationship in the active suspension control system and control method of the off-road multi-axle vehicle of the present application.

[0038] In the figure: 1, vehicle; 2, wheel; 3, vehicle body; 4, active suspension; 5, trailing arm; 6, active actuator; 7, shock absorber; 8, ground; 9, displacement sensor; 10, force sensor; 11, inclination sensor; 12, pitch, roll and height adjustment switch; 13, display screen; 14, pitch, roll and height adjustment reference value. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the following will combine the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, and not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0040] The following further describes embodiments of the application in detail with reference to the accompanying drawings.

[0041] Please refer to Figure 2 , Figure 3 and Figure 4 , the active suspension control system of the off-road multi-axle vehicle provided by the embodiments of the present application, the wheels 2 and the body 3 of the vehicle 1 are connected through the active suspension 4; the active suspension 4 adopts a double wishbone independent suspension structure, and the system is characterized in that:

[0042] The number of axles of the vehicle 1 can be any number of axles equal to or greater than 2 axles, and the number of axles is denoted as n.

[0043] The active suspension 4 of the vehicle 1 is configured with an active actuator 6 having an axial telescopic adjustment function for each wheel 2, and the active actuator 6 and a shock absorber 7 are axially connected in series, and the stiffness characteristics of the shock absorber 7 have been calibrated.

[0044] The vehicle 1 at least includes a displacement sensor 9 for measuring the axial telescopic displacement of the active actuator 6, a force sensor 10 for measuring the axial force, and a tilt angle sensor 11 for measuring the pitch angle and roll angle of the body 3; those skilled in the art should be aware that the displacement sensor 9, the force sensor 10 and the tilt angle sensor 11 are limited to this embodiment configuration, and there are many configurations and methods to obtain the parameters, and these different configurations and methods also belong to the disclosed range of the present application.

[0045] The driver's cabin of the vehicle 1 is configured with pitch, roll and height adjustment switches 12; those skilled in the art should be aware that the pitch, roll and height adjustment switches 12 can adopt any form of lever, button, knob, or touch button provided in the display screen 13, and these different settings also belong to the disclosed range of the present application; the pitch, roll and height adjustment switches 12 respectively send one or more of the pitch or pitch, roll or roll, and height or height adjustment instructions to the active suspension controller.

[0046] The driver's cabin of the vehicle 1 is also configured with a display screen 13 having input and output functions; the display screen 13 can manually modify the pitch, roll and height adjustment reference values 14 corresponding to the pitch, roll and height adjustment switches 12 by the driver; the internal storage of the control system pre-stores the pitch, roll and height adjustment reference values, which are 1°, 1° and 10 cm respectively.

[0047] The control system has artificially specified a number of key nodes reflecting the attitude of the wheels, the suspension and the body, including but not limited to the connection points for causing the relative position changes of the components, such as Figure 6The left wheel bottom center point E, the upper and lower stop points G, I and F, H of the active suspension 4, the hinge points A, B of the transverse arm 5, the vehicle height reference point T defined by the intersection of the longitudinal reference line of the vehicle body 3 and the active suspension cross section, and the node reflecting the vehicle body contour feature.

[0048] Please refer to Figure 4 , the vehicle 1 is configured with an active suspension controller; the active suspension controller stores an active suspension control program that can be executed; when the active suspension control program is executed, the active suspension control method of the off-road multi-axle vehicle is called, first, the current wheel, suspension and vehicle body posture information of the vehicle 1 is output in the form of graphics and numbers in the display screen 13, and the wheel load information calculated according to the axial force of each active actuator 6; then according to the pitch, roll and height adjustment switches 12 triggered by the driver, and the reference values 14 of pitch, roll and height adjustment, the required extension adjustment amount of each active actuator 6 is calculated, and then each active actuator 6 is driven to act synchronously to implement active control; at the same time, the display screen 13 updates the current wheel, suspension and vehicle body posture information of the vehicle 1, and the wheel load information in real time until the active control is completed.

[0049] Please refer to Figure 1 , the active suspension control method of the off-road multi-axle vehicle provided for the embodiment of the present application is based on the double transverse arm independent suspension structure, the inclination angle of the vehicle body 3 relative to the horizontal plane is consistent with Figure 6 the inclination angle α of the wheel 2 relative to the longitudinal symmetry plane of the vehicle; the control method takes the premise that the vehicle is currently driving in off-road environment, and at least three wheels of the vehicle can reliably contact the ground 8; the active suspension control method includes steps 101 to 112:

[0050] Step 101, measure the current pitch angle δ and roll angle α of the vehicle body 3 by the inclination sensor 11.

[0051] Step 102, determine the local coordinate function of each key node of each axle, specifically including: please refer to Figure 5 , based on the wheel 2 on either side of the vehicle, the local rectangular coordinate system o i x i y i z i, i = 1, 2, …, n, wherein the yz coordinate plane is parallel to the cross section of each axle active suspension, the x axis is perpendicular to the yz coordinate plane and points to the direction of vehicle forward movement, the y axis is horizontal to the left, and the z axis is upward; in the local direct coordinate system of each axle, based on the roll angle a of the vehicle body 3 and the rotation angles β and γ of each axle double wishbone 5 relative to the vehicle body 3, the local coordinate functions of each key node of each axle are established in sequence, for example, as shown in FIG. 9, according to the coordinate transformation theory, the y and z axis coordinates of the key node A of the third axle in the local direct coordinate system o3x3y3z3 satisfy the formula Figure 6

[0052]

[0053] In formula 1, r w is the wheel radius, r f is 1 / 2 of the double wishbone height difference, Rot(x, a) is the coordinate conversion matrix, and satisfies the formula

[0054]

[0055] The coordinates of the key node B of the third axle in the local direct coordinate system o3x3y3z3 can be recursively obtained according to the coordinates of the key node A, and satisfy the formula

[0056]

[0057] In formula 3, l d is the length of the wishbone 5, and β is the rotation angle of the right wishbone relative to the vehicle body 3.

[0058] The coordinate functions of each key node of each axle can be derived by the above method by analogy, and it can be understood that the coordinates of the key node in the corresponding local direct coordinate system are functions of the rotation angles β and γ of the wishbone 5 of each axle relative to the vehicle body 3.

[0059] Step 103, determining the distance between the upper stops G and I and the lower stops F and H of the active suspensions on both sides of each axle, specifically comprising:

[0060] The axial extension displacement of each active actuator 6 of each axle is measured by the displacement sensor 9, and the absolute length of each active actuator 6 is determined.

[0061] The axial force of each shock absorber 7 of each axle is measured by the force sensor 10, and the absolute length of each shock absorber 7 is determined according to its stiffness characteristics.

[0062] The distance between the upper stops and the lower stops of the active suspensions 4 on both sides of each axle is determined by combining the two, that is, L GF and L HI .

[0063] ​Step 104, solving the angles β and γ of the double wishbone 5 on both sides of each axle relative to the vehicle body 3, specifically in that:

[0064] One way, for each axle, the active suspension 4, according to the coordinates of the upper and lower dead center of the active suspension 4 on both sides of each axle, and the distance between the upper and lower dead center determined, the angle β and γ of the double wishbone 5 on both sides of each axle relative to the vehicle body 3 is solved.

[0065] Another way, according to L GF , the length of the key node G, B GB , the length of the key node F, B FB , the angle β can be solved according to the triangular angle calculation formula; similarly, according to L HI , the length of the key node I, C IC , the length of the key node C, H CH , the angle γ can be solved according to the triangular angle calculation formula.

[0066] Step 105, determining the y-axis and z-axis coordinates of all key nodes in the local rectangular coordinate system, specifically in that:

[0067] It can be understood that the angles β and γ of the double wishbone on both sides of each axle relative to the vehicle body 3 are substituted into the coordinate function of each key node of each axle in step 102, and the y-axis and z-axis coordinates of all key nodes in the corresponding local rectangular coordinate system are determined.

[0068] Step 106, determining the global coordinates of each key node of the axle in the global coordinate system, specifically including:

[0069] Please refer to Figure 5 , the global coordinate system OXYZ is established with the origin of the local rectangular coordinate system of any axle as the origin, the X axis points horizontally to the front of the vehicle, the Y axis points horizontally to the left, and the Z axis points vertically upward;

[0070] Please refer to Figure 7 , according to the pitch angle δ of the vehicle body 3 measured by the inclination sensor 11 and the y-axis and z-axis coordinates of each key node of the axle in the corresponding local rectangular coordinate system, the three-dimensional coordinates of each key node of the axle in the global coordinate system are determined;

[0071] For example Figure 7 The vehicle body reference point T3, subscript 3 represents that it belongs to the 3rd axle. The y-axis and z-axis coordinates of T3 in the local rectangular coordinate system o3x3y3z3 are Under the premise of ignoring a small amount, its three-dimensional coordinates in the global coordinate system OXYZ satisfy the following formula

[0072]

[0073] The three-dimensional coordinates of each key node of the axle can be determined by the above method by analogy.

[0074] In step 107, the three-dimensional coordinates of each key node of each other axle in the global coordinate system are determined, specifically including:

[0075] According to the pitch angle δ of the vehicle body 3 measured by the inclination sensor 11, the X-axis and Z-axis coordinates of the vehicle height reference point of each other axle in the global coordinate system are determined. The Y-axis coordinate of the vehicle height reference point in the global coordinate system is set to be consistent with the Y-axis coordinate of the vehicle height reference point of the axle on which the global coordinate system is located in the global coordinate system. For example Figure 7 The vehicle body reference point T2, subscript 2 represents that it belongs to the second axle, and its three-dimensional coordinates in the global coordinate system OXYZ satisfy the following formula under the premise of ignoring a small amount

[0076]

[0077] In formula 5, l c1 is the distance between the second axle and the third axle.

[0078] According to the y-axis and z-axis coordinates of the key nodes in the corresponding local rectangular coordinate system, the y-axis and z-axis distances of the vehicle height reference point and the other key nodes of the corresponding axle are determined, and then the three-dimensional coordinates of all key nodes in the global coordinate system are calculated according to the three-dimensional coordinates of each vehicle height reference point in the global coordinate system;

[0079] For example, the y-axis and z-axis coordinates of the key node G2 of the second axle in the local rectangular coordinate system o2x2y2z2 are The y-axis and z-axis coordinates of the corresponding vehicle height reference point T2 are Therefore, under the premise of ignoring a small amount, the three-dimensional coordinates of the key node G2 in the global coordinate system OXYZ satisfy the following formula

[0080]

[0081] The three-dimensional coordinates of all key nodes in the global coordinate system OXYZ can be determined by the above method by analogy. Those skilled in the art should realize that the key nodes listed in the embodiment are only for explanation, and the number of key nodes supplemented on this basis and the expansion of discrete key nodes to structural lines and structural surfaces also belong to the disclosed range of the present application.

[0082] Step 108: The force sensor detects the ground contact status of each wheel 2. If no, that is, a wheel 2 is suspended in the air, the active actuator 6 associated with each suspended wheel 2 is driven to perform axial movement until all wheels 2 are in contact with the ground 8. If yes, that is, all wheels 2 are in contact with the ground, steps 101 to 105 are called back to recalculate the z-axis coordinates of all key nodes in the corresponding local rectangular coordinate system.

[0083] Step 109: Detect the driver's command of pitch, roll and height adjustment switch 12; pick up the reference values ​​14 of pitch, roll and height adjustment input by the driver or pre-stored in the internal memory;

[0084] Step 110, calculate the extension and retraction adjustment of all active actuators 6, specifically including:

[0085] Based on the pitch angle reference value, the height adjustment reference value, and the z-axis coordinates of each vehicle height reference point in the corresponding local rectangular coordinate system, determine the expected z-axis coordinates of each vehicle height reference point after active control.

[0086] by Figure 7 Taking the vehicle reference point T2 as an example, assuming the driver simultaneously triggers the tilt, roll, and height adjustment switch commands, and the reference value 14 for tilt, roll, and height adjustment is the default value, then the z-axis coordinate of the vehicle reference point T2 after active control satisfies... Where △z is the height adjustment reference value of 10cm, k1 is the height adjustment pointer, k1=1 when adjusting to rise, and k1=-1 when adjusting to fall; △δ is the pitch angle adjustment reference value of 1°, k2 is the pitch pointer, k2=-1 when adjusting to fall, and k2=1 when adjusting to rise.

[0087] Let the z-axis coordinates of each vehicle height reference point after active control be equal to the z-axis coordinate function of the corresponding vehicle height reference point established in step 102; simultaneously, let the z-axis coordinate of the center point of the bottom surface of the wheel opposite the origin of the local rectangular coordinate system of each axle be equal to the z-axis coordinate function of that point. It should be noted that the z-axis coordinate functions of the vehicle height reference points and the center point of the bottom surface of the opposite wheel are functions of the rotation angles β and γ of the double wishbone 5 of each axle relative to the vehicle body 3. The rotation angles of the double wishbone on both sides of each axle relative to the vehicle body 3 after active control can be solved using the above equations.

[0088] Substituting the rotation angles of the double wishbones on both sides of each axle relative to the vehicle body 3 into step 102, calculate the coordinates of the upper and lower dead centers of the active suspension 4 on both sides of each axle after active control. Calculate the distance L between the upper and lower dead centers after active control based on the coordinates of the upper and lower dead centers of the active suspension 4 on both sides of each axle after active control. GF and L HIAnd the distance between the current upper and lower dead center is subtracted, so as to determine the telescopic adjustment amount required by all active actuators 6.

[0089] Step 111, control all active actuators 6 to implement active telescopic adjustment synchronously:

[0090] The active suspension control system drives all active actuators 6 to implement active telescopic adjustment synchronously, and at the next moment, the telescopic adjustment amount is completed, that is, the active control of the pitch, roll and height adjustment reference values corresponding to the current input of the driver's pitch, roll and height adjustment switch commands 12 is completed.

[0091] It should be noted that, in order to complete the telescopic adjustment amount at the same time, the telescopic adjustment speed of each active actuator 6 should be set to be proportional to the absolute value of the telescopic adjustment amount.

[0092] Step 112, loop to detect whether the driver's pitch, roll and height adjustment switch commands are stopped: if there are still pitch, roll or height adjustment commands, jump to step 108 and continue to execute the remaining steps; if not, end the active control.

[0093] The embodiment of the present application provides an active suspension control system of a non-road multi-axle vehicle, wherein the output of the current vehicle wheel, suspension, vehicle body posture information and wheel load information calculated by the axial force of each active actuator 6 in the display screen 13 can be realized by calling steps 101 to 107.

[0094] In the description of the present application, it should be noted that the terms "upper", "lower", "first", "second" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise specified and limited, the terms "mounting", "connecting", "connecting" should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be direct connection, or indirect connection through intermediate medium; it can be the communication between two elements inside. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0095] Finally, it should be noted that the above merely describes the preferred embodiments of the present application and the principles of the technology applied. Those skilled in the art will understand that the present application is not limited to the specific embodiments described herein, and that various obvious changes, reconfigurations and substitutions can be made by those skilled in the art without departing from the scope of the present application. Therefore, although the present application has been described in detail through the above embodiments, the present application is not limited to the above embodiments, and can include more other equivalent embodiments without departing from the concept of the present application, and the scope of the present application is determined by the scope of the appended claims.

Claims

1. An active suspension control system for off-road multi-axle vehicle, the wheels and the body of the vehicle are connected by the active suspension, the active suspension adopts double wishbone independent suspension configuration, characterized in that: The number of axles of the vehicle is equal to or greater than 2 axles, and the number of axles is denoted as n; The active suspension of the vehicle is configured with an active actuator with axial telescopic adjustment function for each wheel, and the active actuator is axially connected with a shock absorber, and the stiffness characteristic of the shock absorber has been calibrated; The vehicle at least includes a displacement sensor for measuring the axial telescopic displacement of the active actuator and a force sensor for measuring the axial force, and an inclination sensor for measuring the inclination angle of the body; The cabin of the vehicle is configured with inclination, roll and height adjustment switches; the inclination, roll and height adjustment switches adopt lever, button, knob, or touch button arranged in the display screen; the inclination, roll and height adjustment switches respectively send one or more of inclination down or up, roll left or right, and height up or down instructions to the active suspension controller; The cabin of the vehicle is also configured with a display screen with input and output functions; the display screen can allow the driver to manually modify the inclination, roll and height adjustment reference values corresponding to the inclination, roll and height adjustment switches; the internal memory of the control system pre-stores the inclination, roll and height adjustment reference values, which are 1°, 1° and 10 cm respectively; The control system has artificially specified a plurality of key nodes reflecting the attitude of the wheel, suspension and body, the key nodes include the center point and the contour point of the wheel bottom surface, the upper and lower stop points of the active suspension, the hinge points of the double wishbone, and the wheel height reference point defined by the intersection of the body longitudinal reference line and the cross section of the active suspension, and the node reflecting the body contour characteristics; The vehicle is configured with an active suspension controller; the active suspension controller stores an executable active suspension control program; when the active suspension control program is executed, the active suspension control method for off-road multi-axle vehicle is called, first, the current wheel, suspension and body attitude information of the vehicle is output in the form of graphics and numbers in the display screen, and the wheel load information calculated according to the axial force of each active actuator; then, according to the inclination, roll and height adjustment switches triggered by the driver, and the inclination, roll and height adjustment reference values, the telescopic adjustment amount required to achieve the control expectation of each active actuator is calculated, and then each active actuator is driven to act synchronously to implement active control; at the same time, the display screen updates the current wheel, suspension and body attitude information of the vehicle, and the wheel load information in real time until the active control is completed.

2. The control method of the active suspension control system of the off-road multi-axle vehicle according to claim 1, based on the double wishbone independent suspension architecture, the inclination of the vehicle body relative to the horizontal plane is consistent with the inclination of the vehicle wheel relative to the longitudinal symmetry plane of the vehicle, the control method is based on the premise that the vehicle is currently driving in off-road environment, and at least three wheels of the vehicle are reliably in contact with the ground, characterized in that, Including the following steps: Step 1: measure the current inclination angle and roll angle of the body by the inclination sensor; Step 2: determining the local coordinate functions of each key node of each axle, specifically comprising: based on each wheel on either side of the vehicle, sequentially establishing a local rectangular coordinate system o i x i y i z i of each axle in order from the 1st axle to the nth axle, wherein the yz coordinate plane is parallel to the cross section of the active suspension of each axle, the x axis is perpendicular to the yz coordinate plane, points to the direction of vehicle advancement, the y axis is horizontally leftward, and the z axis is upward; within the local rectangular coordinate system of each axle, sequentially establishing the local coordinate functions of each key node of each axle based on the body roll angle and the rotation angle of each axle double wishbone relative to the vehicle body; Step 3: determining the distance between the upper and lower dead points of the active suspension on both sides of each axle, specifically including: the displacement sensor measures the axial extension displacement of each active actuator of each axle, and then determines the absolute length of each active actuator; the force sensor measures the axial force of each shock absorber of each axle, and then determines the absolute length of each shock absorber according to its stiffness characteristics; combining the two to determine the distance between the upper and lower dead points of the active suspension on both sides of each axle; Step 4: solving the rotation angle of the double wishbone on both sides of each axle relative to the vehicle body: for each axle active suspension, according to the coordinate function of the upper and lower dead points of the active suspension on both sides of each axle, and the distance between the upper and lower dead points, the rotation angle of the double wishbone on both sides of each axle relative to the vehicle body is solved; Step 5: determining the y-axis and z-axis coordinates of all key nodes in the local rectangular coordinate system: substituting the calculated rotation angle of the double wishbone on both sides of each axle relative to the vehicle body into the local coordinate function of each key node of each axle to determine the y-axis and z-axis coordinates of all key nodes in the corresponding local rectangular coordinate system; Step 6: determining the global coordinates of each key node of the axle where the global coordinate system is located, specifically including: establishing a global coordinate system OXYZ with the origin of the local rectangular coordinate system of any axle as the origin, the X-axis pointing horizontally to the front of the vehicle, the Y-axis pointing horizontally to the left, and the Z-axis pointing vertically upward; according to the pitch angle of the vehicle body measured by the inclination sensor and the y-axis and z-axis coordinates of each key node of the axle where the global coordinate system is located in the corresponding local rectangular coordinate system, the three-dimensional coordinates of each key node of the axle in the global coordinate system are determined; Step 7: determining the three-dimensional coordinates of each key node of other axles in the global coordinate system, specifically including: according to the pitch angle of the vehicle body measured by the inclination sensor, the X-axis and Z-axis coordinates of the vehicle height reference point of other axles in the global coordinate system are determined; the Y-axis coordinate of the vehicle height reference point in the global coordinate system is set to be consistent with the Y-axis coordinate of the vehicle height reference point of the axle where the global coordinate system is located in the global coordinate system; according to the y-axis and z-axis coordinates of the key nodes in the corresponding local rectangular coordinate system, the y-axis and z-axis distances between the vehicle height reference point and other key nodes of the corresponding axle are determined, and then the three-dimensional coordinates of all key nodes in the global coordinate system are calculated according to the three-dimensional coordinates of each vehicle height reference point in the global coordinate system; Step 8: detecting the wheel grounding condition and implementing grounding adjustment: if no, i.e. there is a wheel in the air, then driving the active actuator associated with the wheel in the air to act axially until all wheels are in contact with the ground; if yes, i.e. all wheels are in contact with the ground, then re-calling the steps 1 to 5 to re-calculate the z-axis coordinates of all key nodes in the corresponding local rectangular coordinate system; Step 9: detecting the pitch, roll and height adjustment switch instructions of the driver; picking up the reference values of the pitch, roll and height adjustment input by the driver or pre-stored in the internal memory; Step 10: calculating the extension adjustment amount of all active actuators, specifically including: determining the z-axis coordinate of each vehicle height reference point after active control according to the pitch angle reference value, the height adjustment reference value, and the z-axis coordinate of each vehicle height reference point in the corresponding local rectangular coordinate system; setting the z-axis coordinate of each vehicle height reference point after active control to be equal to the z-axis coordinate function of the corresponding vehicle height reference point; at the same time, setting the z-axis coordinate of the center point of the bottom surface of the wheel opposite to the wheel at the origin of the local rectangular coordinate system of each vehicle axle to be equal to the z-axis coordinate function of the point; solving the rotation angle of the double wishbone on both sides of each vehicle axle relative to the vehicle body; substituting the rotation angle of the double wishbone on both sides of each vehicle axle relative to the vehicle body into the coordinate function of each key node of each vehicle axle, calculating the coordinates of the upper and lower stop points of the active suspension on both sides of each vehicle axle after active control, and then determining the extension adjustment amount required by all active actuators; Step 11: controlling all active actuators to implement active extension adjustment synchronously: the active suspension control system drives all active actuators to implement active extension adjustment synchronously, and at the next moment, the extension adjustment amount is completed, i.e. the active control of the pitch, roll, and height adjustment reference values corresponding to the current driver triggered pitch, roll, and height adjustment switch instructions is completed; Step 12: cyclically detecting whether the driver's pitch, roll, and height adjustment switch instructions are stopped: if there are still pitch, roll, or height adjustment instructions, jump to the step of detecting the wheel grounding condition and implementing the grounding adjustment; if not, end the active control.

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