SYSTEM FOR DETERMINING A DAMPER SPEED IN A FIXED RACKING SUSPENSION FOR A VEHICLE

Abstract

A system for determining damper velocity in a rigid axle suspension for a vehicle comprises a rigid axle, a pair of dampers corresponding to a left and right wheel of the vehicle, and a pair of distance sensors. The pair of distance sensors each generates sensor signals indicating the respective distances between the respective sections of the vehicle's frame and the rigid axle. The system also includes one or more controllers in electronic communication with the pair of distance sensors. The one or more controllers access a pair of three-dimensional lookup tables, each corresponding to one of the dampers in the damper pair, with each three-dimensional lookup table defining a relationship between the respective distances measured by the pair of distance sensors and the respective damper length of each damper.

Description

INTRODUCTION

[0001] The present invention relates to a system for determining the damper speed in a rigid axle suspension for a vehicle.

[0002] The publication DE 11 2020 007 542 T5 describes a vehicle control system with a large number of ground clearance sensors, a braking system and a control unit.

[0003] A solid axle or rigid axle refers to a suspension design in which a single beam or shaft connects the left and right wheels of a vehicle. An active damper refers to a damper that exerts an independent force on a vehicle's suspension to improve ride comfort. A semi-active damper refers to a damper that can change the damper's viscous damping coefficient; however, unlike an active damper, a semi-active damper is not capable of transferring energy to a vehicle's suspension. If the damper's position is known, its velocity can be determined by deriving the position with respect to time. It is reasonable to assume that during vehicle operation, understanding the damper velocity at any given time is necessary to determine the system's performance, including its performance at the vehicle level.

[0004] Vehicles equipped with a rigid rear axle behave differently compared to those with independent rear suspension. Therefore, determining the position and speed of a damper in a vehicle with a rigid rear axle presents distinct challenges. For example, a vehicle's rigid rear axle can either hop or bounce. Wheel hop refers to both rear wheels of the rigid rear axle moving in the same direction at the same speed, while bounce refers to the left and right wheels moving in different directions and / or at different speeds.Therefore, the velocity of the damper corresponding to the left wheel of a vehicle equipped with a rigid rear axle cannot be calibrated in the same way as the velocity of the damper corresponding to the right wheel. In addition to wheel hop and tramp, most rigid rear axles also incorporate left and right dampers that are fanned out relative to each other along all three axes of the vehicle's coordinate system. This staggered arrangement of dampers further complicates the challenges faced when attempting to determine the velocity of a damper for a vehicle equipped with a rigid rear axle.

[0005] Although known rigid rear axles fulfill their intended purpose, one object of the invention in this field is therefore to determine the speed of a damper for vehicles equipped with a rigid rear axle. SUMMARY

[0006] The aforementioned problem is solved by the features of claim 1. Advantageous further developments of the invention are shown in the dependent claims, the description and the drawings.

[0007] According to several aspects of the invention, a system for determining a damper velocity within a rigid axle suspension for a vehicle containing a frame is disclosed. The system includes a rigid axle connecting a left and a right wheel of the vehicle, and a pair of dampers corresponding to the left and right wheels of the vehicle, respectively, each damper defining a specific damper length. The system also includes a pair of distance sensors corresponding to the left and right wheels of the vehicle, respectively, each pair of distance sensors generating sensor signals indicating the respective distances between sections of the vehicle frame and the rigid axle. The system also includes one or more controllers in electronic communication with the pair of distance sensors.The one or more controllers access a pair of three-dimensional lookup tables, each corresponding to one of the dampers in the damper pair. Each three-dimensional lookup table defines a relationship between the respective distances measured by the pair of distance sensors and the respective damper length of each damper. The one or more controllers contain one or more processors that execute instructions to receive sensor signals from the pair of distance sensors indicating the respective distances between the vehicle frame and the rigid axle.In response to receiving the sensor signals, the one or more controllers locate a value in each of the two three-dimensional lookup tables, where the value represents a respective damper length of one of the dampers corresponding to the respective distances measured by the pair of distance sensors, and derive the respective damper length of each damper with respect to time to determine a velocity corresponding to each damper.

[0008] According to another aspect, each three-dimensional reference table is determined on the basis of a kinematic study in which the rigid axle suspension is in a curb position, a compression position and a rebound position of the vehicle.

[0009] According to another aspect, the kinematic study involves keeping either a wheel arrangement corresponding to the left wheel or a wheel arrangement corresponding to the right wheel of the vehicle stationary, while a remaining wheel arrangement is deflected through an entire range of motion corresponding to the remaining wheel arrangement at predefined increases in distance.

[0010] According to one aspect, the predefined increases in distance amount to approximately ten millimeters.

[0011] According to another aspect, the curb position of the vehicle represents a position of the rigid axle suspension in which the vehicle is at rest on level ground with a full fuel tank, no payload and no passengers.

[0012] According to yet another aspect, the damper pair is fully compressed and the respective damper length corresponding to each damper is at a minimum value when the vehicle is in the curb position.

[0013] According to one aspect, the damper pair is completely relaxed and the respective damper length, which corresponds to each damper, is at a maximum value in the rebound position.

[0014] According to another aspect, the damper pair is arranged in a fan shape offset from each other in an x-axis, a y-axis and a z-axis of a vehicle coordinate system of the vehicle.

[0015] According to another aspect, the pair of distance sensors includes rotational height sensors or linear distance sensors or optical distance sensors or accelerometers.

[0016] According to one aspect, the damper pair includes active dampers or semi-active dampers.

[0017] According to another aspect, the rigid axle connects the rear wheels of the vehicle.

[0018] According to a non-independently claimed aspect, a method for determining a damper velocity in a rigid axle suspension for a vehicle containing a frame is described. The method comprises receiving sensor signals indicating the respective distances between the vehicle frame and a rigid axle from a pair of distance sensors by one or more controllers, wherein the pair of distance sensors corresponds to a left and a right wheel of the vehicle, respectively, and a pair of dampers corresponds to the left and a right wheel of the vehicle, respectively. Each damper defines a respective damper length.In response to receiving the sensor signals, the method comprises the one or more controllers locating a value in each of the two three-dimensional lookup tables, wherein the value represents a respective damper length of one of the dampers corresponding to the respective distances measured by the pair of distance sensors, and wherein each three-dimensional lookup table defines a relationship between the respective distances measured by the pair of distance sensors and the respective damper length of each damper. The method comprises the one or more controllers deriving the respective damper length of each damper with respect to time to determine a velocity corresponding to each damper.

[0019] According to a further, non-independently claimed aspect, a system for determining a damper velocity in a rigid axle suspension for a vehicle containing a frame is disclosed. The method includes a rigid axle connecting a left and a right rear wheel of the vehicle, and a pair of dampers corresponding to the left and right rear wheels of the vehicle, respectively, each damper defining a specific damper length. The system also includes a pair of distance sensors corresponding to the left and right rear wheels of the vehicle, respectively, each pair of distance sensors generating sensor signals indicating the respective distances between the respective sections of the vehicle frame and the rigid axle.The system comprises one or more controllers in electronic communication with the pair of distance sensors, wherein the one or more controllers access a pair of three-dimensional lookup tables, each corresponding to one of the dampers of the damper pair, and wherein each three-dimensional lookup table defines a relationship between the respective distances measured by the pair of distance sensors and the respective damper lengths of each damper, and each three-dimensional lookup table is determined based on a kinematic study in which the rigid axle suspension is in a curb position, a compression position, and a rebound position of the vehicle. The one or more controllers contain one or more processors that execute instructions to receive the sensor signals from the pair of distance sensors, which specify the respective distances between the vehicle frame and the rigid axle.In response to receiving the sensor signals, the one or more controllers locate a value in each of the two three-dimensional lookup tables, where the value represents the respective damper length of one of the dampers, corresponding to the respective distances measured by the pair of distance sensors. The one or more controllers derive the respective damper length of each damper with respect to time to determine a velocity corresponding to each damper.

[0020] According to another aspect, the kinematic study involves either keeping a wheel arrangement corresponding to the left rear wheel or the wheel arrangement corresponding to the right rear wheel of the vehicle stationary, while a remaining wheel arrangement is deflected through an entire range of motion corresponding to the remaining wheel arrangement at predefined increases in distance.

[0021] According to another aspect, the predefined increases in distance amount to approximately ten millimeters.

[0022] According to one aspect, the curb position of the vehicle represents a position of the rigid axle suspension in which the vehicle is at rest on level ground with a full fuel tank, no payload and no passengers.

[0023] According to another aspect, the damper pair is fully compressed and the respective damper length corresponding to each damper is at a minimum value when the vehicle is in the curb position.

[0024] According to yet another aspect, the damper pair is completely relaxed and the respective damper length, which corresponds to each damper, is at its maximum value in the rebound position.

[0025] According to one aspect, the damper pair is arranged in a fan shape offset from each other in an x-axis, a y-axis and a z-axis of a vehicle coordinate system of the vehicle.

[0026] According to another aspect, the pair of distance sensors includes rotational height sensors or linear distance sensors or optical distance sensors or accelerometers.

[0027] Further areas of application will become apparent from the description provided here. It should be understood that the description and specific examples serve only as illustrations. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings described here are for illustrative purposes only; they show: Fig. 1 a perspective view of an exemplary vehicle according to an exemplary embodiment, which includes a set of front wheels and a set of rear wheels; Fig. 2 a top view of an exemplary rigid axle suspension according to an exemplary embodiment, which includes a rigid axle for connecting the rear wheels of the vehicle in Fig. 1 of the vehicle shown contains; Fig. 3 a perspective view of the in Fig. 2 rigid axle suspension shown according to an exemplary embodiment, which includes one or more controllers in electronic communication with a pair of position sensors; Fig. 4 a rear view of the rigid axle suspension according to an exemplary embodiment; Fig. 5 a side view of the rigid axle suspension according to an exemplary embodiment; Fig. 6 an exemplary three-dimensional lookup table according to an exemplary embodiment, which is stored in the memory of one or more of the in Fig. The controller shown in section 3 is stored; and Fig. 7 A representation of the rigid axle suspension according to an exemplary embodiment in a curb position. DETAILED DESCRIPTION

[0029] The following description is merely exemplary.

[0030] In Fig. Figure 1 shows a vehicle 10 containing left and right front wheels 12A, 12B and left and right rear wheels 14A, 14B. Fig. Figure 2 shows a top view of a system 18 which includes an exemplary rigid axle suspension 20, which is attached to the rear wheels 14A, 14B of the vehicle shown in the diagram. Fig. 1 of the vehicle shown is assigned to 10, and Fig. Figure 3 shows a perspective view of the in Fig. 2 rigid axle suspension shown 20. According to the in Fig. In the non-restrictive embodiment shown in Figure 1, the vehicle 10 is a truck. However, it can be assumed that the vehicle 10 can be any type of vehicle, such as, but not limited to, a sedan, an SUV, a van, a motorhome, a commercial vehicle, or an agricultural vehicle.

[0031] As in the Fig. 1, Fig. 2 and Fig. As shown in Figure 3, the system 18 contains a rigid axle 22, a differential 24, a pair of preload elements 26A, 26B (in Fig. 2 visible), corresponding to the left and right rear wheels 14A, 14B of vehicle 10, a pair of dampers 28A, 28B corresponding to the left and right rear wheels 14A, 14B of vehicle 10, a pair of distance sensors 30A, 30B ( Fig. 3), corresponding to the left and right rear wheels 14A, 14B of the vehicle 10, a pair of wheel assemblies 32A, 32B corresponding to the left and right rear wheels 14A, 14B of the vehicle 10, and one or more controllers 34 ( Fig. 3) in electronic communication with the pair of distance sensors 30A, 30B. Although the rear wheels 14A, 14B are described in relation to the rigid axle suspension 20 shown in the figures, it can be assumed that the rigid axle suspension 20 is not limited to the rear wheels of a vehicle and can also be used for the front wheels of a vehicle.

[0032] The differential 24 couples with a drivetrain (not shown) of the vehicle 10 and distributes the drive torque to the rear wheels 14A, 14B ( Fig. 1) The preload elements 26A, 26B ( Fig. 2) connect the rigid axle 22 to a respective section of a frame 36A, 36B of the vehicle 10, wherein the section of frame 36A corresponds to the left rear wheel 14A and the section of frame 36B corresponds to the right rear wheel 14B. According to the in Fig. In the non-restrictive embodiment shown in Figure 2, the preload elements 26A, 26B are depicted as leaf springs; however, it can be assumed that the rigid axle suspension 20 is not limited to leaf springs. According to a further embodiment, the preload elements 26A, 26B can instead be coil springs or air springs.

[0033] Fig. Figure 4 shows a rear view of the rigid axle suspension 20 and Fig. 5 a side view of the rigid axle suspension 20. In the Fig. Items 2-5 contain dampers 28A, 28B, each with a telescopic housing 40A, 40B, an upper mounting 42A, 42B, and a lower mounting 44A, 44B (both lower mountings 44A, 44B are in the Fig. 4 and Fig. 5 visible). The lower mounting 44A, 44B of each damper 28A, 28B is connected to a wheel hub 46A, 46B (in the Fig. 4 and Fig. 5 visible) connected to a corresponding wheel arrangement 32A, 32B. The dampers 28A, 28B can be active dampers or semi-active dampers.

[0034] According to the embodiment shown in the figures, the pair of dampers 28A, 28B are arranged in a fan-like arrangement offset from one another in all three axes (the x-axis, y-axis and z-axis) of the vehicle coordinate system corresponding to the vehicle 10. As shown in particular in Fig. Figure 2 shows an angle β1 between the x-axis of the vehicle coordinate system and an axis of symmetry A1 of the damper 28A, which is attached to the left rear wheel 14A ( Fig. 1) of the vehicle, is measured, not equal to an angle α1 measured between the x-axis of the vehicle coordinate system and an axis of symmetry B1 of the damper 28B, which corresponds to the right rear wheel 14B of the vehicle. As in Fig. As shown in Figure 4, an angle β2 measured between the z-axis of the vehicle coordinate system and the axis of symmetry A1 of the damper 28A, corresponding to the left rear wheel 14A of the vehicle, is similarly not equal to an angle α2 measured between the x-axis of the vehicle coordinate system and the axis of symmetry B1 of the damper 28B, corresponding to the right rear wheel 14B of the vehicle 10. As shown in Fig. As shown in Figure 5, an angle β3 measured between the y-axis of the vehicle coordinate system and the axis of symmetry A1 of damper 28A, corresponding to the left rear wheel 14A of vehicle 10, is not equal to an angle α3 measured between the y-axis of the vehicle coordinate system and the axis of symmetry B1 of damper 28B, corresponding to the right rear wheel 14B of vehicle 10. However, it can be assumed that the pair of dampers 28A, 28B is not limited to the arrangement shown in the figures and that the dampers 28A, 28B can also be arranged symmetrically to each other with respect to any of the three axes of the vehicle coordinate system.

[0035] As in Fig. As shown in Figure 3, according to the non-restrictive embodiment shown, the distance sensors 30A, 30B are rotational height sensors, each comprising a connection 50A, 50B, a crank arm 52A, 52B, and a bracket 54A, 54B. The distance sensors 30A, 30B are mounted by the respective brackets 54A, 54B on the respective sections of the frame 36A, 36B of the vehicle 10 and measure the respective distances D1, D2 between the respective sections of the frame 36A, 36B and the rigid axle 22. Since the dampers 28A, 28B are arranged offset from each other, it can be assumed that the distance D1, which corresponds to the left rear wheel 14A ( Fig. 1) of vehicle 10, is not equal to the distance D2, which corresponds to the right rear wheel 14B of vehicle 10.

[0036] Although a rotational height sensor is shown, it can be assumed that the distance sensors 30A, 30B can be any type of distance sensor for measuring the respective distances D1, D2 between the respective sections of the frame 36A, 36B and the rigid axis 22, such as linear distance sensors, optical distance sensors, and accelerometers. Some examples of linear distance sensors include linear displacement sensors and cable displacement sensors. Furthermore, accelerometers can be arranged on the respective sections of the frame 36A, 36B, as well as on the dampers 28A, 28B, to achieve a similar result. However, it can be assumed that the respective outputs of the accelerometers are integrated rather than derived to calculate the damper velocity.The distance sensors 30A, 30B generate sensor signals that indicate the respective distances D1, D2 between the respective sections of the frame 36A, 36B and the rigid axle 22, wherein the one or more controllers 34 receive the sensor signals from the distance sensors 30A, 30B.

[0037] As explained below, the one or more controllers 34 determine a speed of each damper 28A, 28B based on the sensor signals received from the pair of distance sensors 30A, 30B. Fig. Figure 6 shows an exemplary three-dimensional reference table 60, corresponding to one of the dampers 28A, 28B, which are part of the rigid axle suspension 20. According to the non-restrictive embodiment shown in Fig. As shown in Figure 4, the three-dimensional reference table 60 corresponds to the damper 28A, which corresponds to the left rear wheel 14A ( Fig. 1) corresponds, however, it can be assumed that a similar three-dimensional reference table also exists with regard to the damper 28B, which corresponds to the right rear wheel 14B.

[0038] In the Fig. 3, Fig. 4 and Fig. 6. One or more controllers 34 access a pair of three-dimensional lookup tables 60, each corresponding to one of the dampers 28A, 28B, wherein each three-dimensional lookup table 60 defines a relationship between the respective distances D1, D2 measured by the distance sensors 30A, 30B, and a respective damper length L1, L2 of the dampers 28A, 28B. That is, each three-dimensional lookup table 60 gives a damper length L1, L2 for one of the dampers 28A, 28B based on the distance D1 measured by the distance sensor 30A, which is attached to the left rear wheel 14A ( Fig. 1) of vehicle 10, as well as the distance D2, which is measured by the distance sensor 30B, which corresponds to the right rear wheel 14B of vehicle 10. As in Fig. As shown in Figure 4, the damper length L1, L2 represents a vertical distance between the upper mounting 42A, 42B and the lower mounting 44A, 44B of each of the dampers 28A, 28B. Since the dampers 28A, 28B are arranged offset from each other, it can be assumed that the damper length L1 for the damper 28A, which is for the left rear wheel 14A ( Fig. 1) of vehicle 10, is not equal to the damper length L2 for the damper 28B, which corresponds to the right rear wheel 14B of vehicle 10.

[0039] The one or more controllers 34 store the three-dimensional lookup tables 60 corresponding to the damper pair 28A, 28B in memory. Alternatively, according to a further embodiment, the three-dimensional lookup tables 60 are stored in a database, wherein the one or more controllers 34 are in electronic communication with the database. It can be assumed that a single value generated by one of the distance sensors 30A, 30B can represent more than one damper length L1, L2 of a respective damper 28A, 28B. In other words, it can be assumed that the damper length L1, L2 of each damper 28A, 28B cannot be determined solely on the basis of sensor signals generated by only one of the distance sensors 30A, 30B. For example, the damper length L1 of the damper 28A, which corresponds to the left rear wheel 14A ( Fig. 1) corresponds, not be determined solely on the basis of the sensor signals generated by the distance sensor 30A, which corresponds to the left rear wheel 14A.

[0040] Each three-dimensional reference table 60 contains an x-axis 62, a y-axis 64, and a z-axis 66. The x-axis 62 and the y-axis 64 each correspond to the sensor signals from one of the pair of distance sensors 30A, 30B, which measures the damper length L ( Fig. 3) one of the dampers 28 indicates. In which in Fig. In the example shown, the x-axis 62 of the three-dimensional reference table 60 corresponds to the distance sensor 30A for the damper 28A, which is attached to the left rear wheel 14A ( Fig. 1) corresponds to, and the y-axis 64 of the three-dimensional lookup table 60 corresponds to the distance sensor 30B for the damper 28B, which corresponds to the right rear wheel 14B. The z-axis 66 of the three-dimensional lookup table 60 corresponds to the damper length L1, L2 ( Fig. 4) one of the dampers 28A, 28B. Although in Fig. 6 the x-axis 62 the distance sensor 30A for the damper 28A, which is connected to the left rear wheel 14A ( Fig. 1) corresponds to the y-axis 64, which corresponds to the distance sensor 30B for the damper 28B, which corresponds to the right rear wheel 14B, and the z-axis corresponds to the damper length L1 for the damper 28A, it can be assumed that the three-dimensional lookup table 60 does not refer to the configuration that is in Fig. As shown in Figure 4, the x-axis 62, y-axis 64, and z-axis 66 can correspond to other variables instead. According to another embodiment, the x-axis 62 can, for example, correspond to the distance sensor 30B for the damper, which corresponds to the right rear wheel 14B, or to the damper length L1.

[0041] In the Fig. 2, Fig. 3, Fig. 4 and Fig. 6. The one or more controllers 34 receive sensor signals from the pair of distance sensors 30A, 30B, which indicate the respective distances D1, D2 between the respective sections of the frame 36A, 36B of the vehicle 10 and the rigid axle 22. In response to receiving the sensor signals from the pair of distance sensors 30A, 30B, the one or more controllers 34 determine the respective damper lengths L1, L2 of the damper pair 28A, 28B by locating a value in both three-dimensional lookup tables 60, where the value represents a respective damper length L1, L2 of one of the dampers 28A, 28B, corresponding to the respective distances D1, D2 measured by the pair of distance sensors 30A, 30B.Once the respective damper lengths L1, L2 of the damper pair 28A, 28B have been determined, the one or more controllers 34 then derive the damper length L1, L2 of each damper 28A, 28B with respect to time in order to determine a velocity corresponding to both dampers 28A, 28B. It is assumed that the one or more controllers 34 determine a requested damper output force for both dampers 28A, 28B. The one or more controllers 34 then determine the value of a current signal that is transmitted to one of the dampers 28A, 28B to generate the corresponding requested damper output force. The value of the current signal is determined based on the value of the requested damper output force and the instantaneous velocity to which one of the dampers 28A, 28B is subjected.

[0042] The three-dimensional reference table 60 is determined on the basis of a kinematic study in which the rigid axle suspension 20 is in a curb position, a compression position, and a rebound position of the vehicle 10. The kinematic study includes restricting and holding in a fixed position either the wheel assembly 32A, which is attached to the left rear wheel 14A ( Fig. 1) corresponds to, or to the wheel arrangement 32B, which corresponds to the right rear wheel 14B ( Fig. 1) of the vehicle 10, while the remaining wheel assembly 32B is deflected through a full range of motion corresponding to that of the remaining wheel assembly 32B of the rigid axle suspension 20 at predefined increases in distance, and the process is repeated by subsequently limiting and holding the remaining wheel assembly 32B in a fixed position and deflecting the other wheel assembly 32A for the curb position, compression position, and rebound position of the vehicle 10. It can be assumed that the kinematic study can be carried out based on empirical data generated by testing the vehicle 10 in a real-world environment, or alternatively, the kinematic study can be carried out based on a computer simulation.

[0043] Fig. Figure 7 shows an exemplary representation of the rigid axle suspension 20 in the curb position, in which the wheel arrangement 32A, which belongs to the left rear wheel 14A ( Fig. 1) corresponds to, is restricted, and is held stationary on a corresponding rotor 56A, while the wheel assembly 32B, corresponding to the right rear wheel 14B, is deflected through the entire range of motion corresponding to that of the wheel assembly 32B at the predefined increases in distance. According to a non-restrictive embodiment, the predefined increases in distance are approximately ten millimeters, although it can be assumed that the predefined increases in distance can be adjusted based on the specific application. The curb position of the vehicle 10 represents a position of the rigid axle suspension 20 in which the vehicle 10 is at rest on level ground with a full fuel tank (if applicable), no payload, and no passengers.

[0044] As in the Fig. 6 and Fig. As shown in Figure 7, the data collected during the kinematic study in the curb position are represented by several centrally located data points 70 arranged along a three-dimensional surface diagram 72 of the three-dimensional lookup table 60. Each of the centrally located data points 70 of the three-dimensional lookup table 60 represents a center point of the three-dimensional surface diagram 72 with respect to the damper length L1 of the damper 28A (i.e., the z-axis 66 of the three-dimensional lookup table 60). The centrally located data points 70 of the three-dimensional surface diagram 72 correspond to the damper length L1 of the damper 28A, which is restricted and held stationary in the curb position.

[0045] In the compression position, the damper pair 28A, 28B is fully compressed, and the damper length L1, L2 corresponding to each damper 28A, 28B is at its minimum value. The data collected during the kinematic study in the compression position are represented by several data points 74 of the minima arranged along the three-dimensional surface diagram 72 of the three-dimensional reference table 60. The data points 74 of the minima in the three-dimensional reference table 60 each represent a minimum value of the three-dimensional surface diagram 72 with respect to the damper length L1 of damper 28A (i.e., the z-axis 66 of the three-dimensional reference table 60). The data points 74 of the minima in the three-dimensional surface diagram 72 correspond to the damper length L1 of damper 28A, which is restricted and held stationary in the fully compressed position.

[0046] In the rebound position, both dampers 28A, 28B are fully relaxed and the damper length L1, L2, corresponding to each damper 28A, 28B, is at its maximum value. The rebound position is then represented when the wheels 12A, 12B, 14A, 14B ( Fig. 1) of vehicle 10 no longer touch the ground. For example, wheels 12A, 12B, 14A, 14B ( Fig. 1) of the vehicle 10 from the ground when the vehicle 10 is on a lifting platform. The data collected during the kinematic study in the rebound position are represented by several data points 76 of the maxima arranged along the three-dimensional surface diagram 72 of the three-dimensional reference table 60. The data points 76 of the maxima of the three-dimensional surface diagram 72 correspond to the damper length L1 of the damper 28A, which is restricted and held stationary in the rebound position.

[0047] With general reference to the figures, the disclosed system provides various technical effects and advantages. Specifically, the system provides a method for robustly determining the velocity of each damper of a rigid axle suspension based on sensor readings generated by two distance sensors corresponding to the left and right wheels of the vehicle. It can be assumed that the disclosed method uses known distance sensors and therefore requires no modification of the mechanical or electrical systems of a vehicle. Furthermore, the current approach requires no additional hardware components; only software modifications are necessary to implement the disclosed system in a known vehicle.

[0048] Controllers can refer to or be part of an electronic circuit, a combinational logic circuit, a field-programmable gate array (FPGA), a processor (shared, dedicated, or a group) that executes code, or a combination of some or all of the above, such as in a system on a chip. Additionally, controllers can be microprocessor-based, such as a computer that has at least one processor, memory (RAM and / or ROM), and associated input and output buses. The processor can operate under the control of an operating system residing in memory. The operating system can manage computer resources such that computer program code, embodied as one or more computer software applications, such as an application residing in main memory, can instruct the processor to execute instructions.In an alternative embodiment, the processor can execute the application directly, in which case the operating system can be omitted.

Claims

[1] System (18) for determining a damper velocity in a rigid axle suspension (20) for a vehicle (10) which includes a frame, wherein the system (18) comprises: a rigid axle (22) connecting a left wheel (14A) and a right wheel (14B) of the vehicle (10); a pair of dampers (28A, 28B) corresponding to the left and right wheels (14A, 14B) of the vehicle (10), each damper (28A, 28B) defining a respective damper length (L1, L2); a pair of distance sensors (30A, 30B) corresponding to the left and right wheels (14A, 14B) of the vehicle (10), wherein the pair of distance sensors (30A, 30B) each generates sensor signals indicating the respective distances (D1, D2) between the respective sections of the frame (36A, 36B) of the vehicle (10) and the rigid axle (22); and one or more controllers (34) in electronic communication with the pair of distance sensors (30A, 30B), wherein the one or more controllers (34) access a pair of three-dimensional lookup tables (60), each corresponding to one of the dampers (28A, 28B) of the damper pair (28A, 28B), and wherein each three-dimensional lookup table (60) defines a relationship between the respective distances (D1, D2) measured by the pair of distance sensors (30A, 30B) and the respective damper length (L1, L2) of each damper (28A, 28B), and wherein the one or more controllers (34) contain one or more processors that execute instructions to: Receiving the sensor signals indicating the respective distances (D1, D2) between the vehicle frame (10) and the rigid axle (22) from the pair of distance sensors (30A, 30B); Locating a value in both three-dimensional lookup tables (60) in response to receiving the sensor signals, wherein the value represents a respective damper length (L1, L2) of one of the dampers (28A, 28B) corresponding to the respective distances (D1, D2) measured by the pair of distance sensors (30A, 30B); and Deriving the respective damper length (L1, L2) of each damper (28A, 28B) with respect to time to determine a velocity corresponding to each damper (28A, 28B). [2] System (18) according to claim 1, wherein each three-dimensional reference table (60) is determined on the basis of a kinematic study in which the rigid axle suspension (20) is in a curb position, a compression position and a rebound position of the vehicle (10). [3] System (18) according to claim 2, wherein the kinematic study comprises holding either the wheel assembly (32A) corresponding to the left wheel (32A) or the wheel assembly (32B) corresponding to the right wheel (14B) of the vehicle (10) in a fixed position, while the respective remaining wheel assembly (32A, 32B) is deflected through an entire range of motion corresponding to the remaining wheel assembly (32A, 32B) at predefined increases in distance. [4] System (18) according to claim 3, wherein the predefined increases in the distance are about ten millimeters. [5] System (18) according to claim 2, wherein the curb position of the vehicle (10) represents a position of the rigid axle suspension (20) in which the vehicle (10) is at rest on level ground with a full fuel tank, no payload and no passengers. [6] System (18) according to claim 2, wherein the damper pair (28A, 28B) is fully compressed and the respective damper length (L1, L2) corresponding to each damper (28A, 28B) is at a minimum value when the vehicle (10) is in the curb position. [7] System (18) according to claim 2, wherein the damper pair (28A, 28B) is fully relaxed and the respective damper length (L1, L2) corresponding to each damper (28A, 28B) is at a maximum value in the rebound position. [8] System (18) according to claim 1, wherein the damper pair (28A, 28B) is arranged fan-shaped offset from each other in an x-axis (62), a y-axis (64) and a z-axis (66) of a vehicle coordinate system of the vehicle (10). [9] System (18) according to claim 1, wherein the pair of distance sensors (30A, 30B) comprises rotation height sensors or linear distance sensors or optical distance sensors or accelerometers. [10] System (18) according to claim 1, wherein the damper pair (28A, 28B) includes active dampers (28A, 28B) or semi-active dampers (28A, 28B).

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