Air suspension control

Abstract

Example embodiments relate to a suspension system for a vehicle, the suspension system including a controller configured to determine a roughness of a ground surface associated with the vehicle. The controller can be further configured to determine a height adjustment parameter for the suspension system based on the determined roughness and facilitate modification of the suspension system based on the determined height adjustment parameter. Example methods are provided that can include determining, using a controller, a roughness of a ground surface associated with a vehicle, the roughness determined based on a body height. The method can also include determining, using the controller, a height adjustment parameter for a suspension system of the vehicle based on the determined roughness.

Description

[0001] Cross Reference to Related Applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 226,679, filed July 28, 2021, and U.S. Provisional Patent Application No. 63 / 240,689, filed September 3, 2021, the contents of each of which are expressly incorporated by reference herein in their entirety. TECHNICAL FIELD

[0003] The present disclosure relates to a vehicle suspension system, and more particularly to a vehicle suspension system that allows for adjustment of the vehicle body height under different conditions. BACKGROUND

[0004] Some vehicle suspension systems allow for manual or automatic adjustment of the vehicle height. For example, a user can be allowed to select different body heights, for example, to modify the off-road capability of the vehicle. In another example, a vehicle can have an automatic leveling system that levels the vehicle in response to changes in the vehicle load, for example, in response to placing a heavy load in a cargo area at the rear of the vehicle. Rough road surfaces can cause the vehicle to perform leveling events excessively such that the vehicle attempts to respond to rapid changes in wheel position. Vehicle occupants can notice the excessive activity and unnecessary actuation caused by the leveling system. Accordingly, in some example instances herein, a roughness metric or estimator dynamically estimates a roughness value that can be used to relax the acceptable control tolerance of an air suspension system when the surface traversed by the vehicle is relatively rougher. On these relatively rough surfaces / roads, excessive corrections by the leveling system can be reduced or completely prevented. Additionally, the tolerance can be changed in response to determining that the road surface is relatively smooth, allowing the leveling system to make leveling adjustments as needed.

[0005] Another issue arises with vehicles having automatic leveling systems when the suspension or other components are installed or serviced incorrectly. For example, if a vehicle component that is installed or serviced incorrectly will cause the vehicle to tilt (e.g., toward one side or corner of the vehicle), then in response, the vehicle’s automatic leveling will necessarily increase the load applied to the ground by the wheels at that side or corner, creating an asymmetry in the wheel load of the vehicle. The asymmetrical corner load can have a negative impact on the vehicle’s dynamic behavior. Furthermore, the level appearance of the vehicle can mask the underlying condition to the servicing or assembly personnel. Accordingly, in some example instances, the uneven corner load can be addressed by employing a control method for leveling the vehicle suspension in a manner that facilitates identification of an incorrect vehicle suspension installation or setup, while responding appropriately during normal conditions or operation. SUMMARY

[0006] In at least some example instances, a suspension system for a vehicle includes a controller configured to determine a roughness of a ground surface associated with the vehicle. The controller can be further configured to determine a height adjustment parameter for the suspension system based on the determined roughness. The controller can also be configured to facilitate modification of the suspension system based on the determined height adjustment parameter.

[0007] In at least some example methods, the height adjustment parameter includes an adjustment to one of a ride height or a height adjustment tolerance.

[0008] In some examples, the controller is configured to determine the height adjustment parameter based on the determined roughness by modifying the height adjustment tolerance in response to a change in the roughness of the ground surface.

[0009] In some examples, the controller can be configured to determine the roughness by determining a roughness metric based on a change in a corner height error over a time period corresponding to the ground surface traversed during the time period. In a subset of these examples, the corner height error is a difference between an expected ride height and an actual ride height.

[0010] In at least some examples, the controller is configured to determine the roughness by determining a ground input magnitude based on a change in the corner height error over the time period.

[0011] In at least some examples, the controller is configured to determine the roughness by determining a moving average of the change in the corner height error over the time period.

[0012] In at least some examples, the suspension system includes one or more air springs, where the controller is configured to change an amount of air contained by the one or more air springs to change a corresponding vehicle corner height.

[0013] In at least some example methods, the suspension system includes an air reservoir having a compressed air storage volume and a valve block assembly controlled by the controller. The valve block assembly is configured to direct a flow of air from the air storage volume to one or more air springs of the suspension system.

[0014] In at least some example instances, the controller is configured to determine a twist of the suspension system. The twist can be based on a difference between a first lateral displacement difference of a front axle of the vehicle and a second lateral displacement difference of a rear axle of the vehicle. The controller can be configured to determine a subsequent height adjustment parameter based on the twist of the suspension system.

[0015] In at least some examples, an air suspension system for a vehicle is provided that includes one or more air springs and a controller configured to determine a roughness of a ground surface associated with the vehicle. The controller can also be configured to determine a height adjustment parameter for the suspension system based on the determined roughness, where the height adjustment is achieved by changing an amount of air contained by the one or more air springs.

[0016] In at least some of these examples, the height adjustment parameter includes an adjustment to one of a vehicle body height or a height adjustment tolerance.

[0017] In at least some example methods, a method includes determining, using a controller, a roughness of a ground surface associated with a vehicle, the roughness determined based on a vehicle body height. The method can also include determining, using the controller, a height adjustment for a suspension system of the vehicle based on the determined roughness.

[0018] In at least some example methods, determining the roughness includes determining a change in a corner height error over a time period corresponding to a ground surface traversed during the time period. In at least a subset of these examples, determining the roughness includes determining a change in a moving average of the corner height error.

[0019] In at least some example methods, determining the roughness includes determining a moving average of the corner height error.

[0020] In at least some example instances of the method, the corner height error is a difference between an expected vehicle body height and an actual vehicle body height.

[0021] In at least some example methods, the method further includes increasing the height adjustment tolerance in response to an increase in the roughness.

[0022] In at least some example methods, the method further includes decreasing the height adjustment tolerance in response to a decrease in the roughness metric of the road surface.

[0023] In at least some example methods, the method further includes determining a twist of the suspension system based on a difference between a first lateral displacement difference of a front axle of the vehicle and a second lateral displacement difference of a rear axle of the vehicle. The method can also include determining a subsequent height adjustment parameter based at least on the determined twist. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 A schematic view of a vehicle having a suspension system that allows for adjustment of a vehicle body height via adjustable air springs in accordance with example methods is shown;

[0025] Figure 2 A schematic view of a vehicle having a suspension system that allows for adjustment of a vehicle body height via adjustable air springs in accordance with example methods is shown;Figure 1 schematic diagram of a vehicle showing exemplary pneumatic and electrical connections of a suspension system;

[0026] Figure 3 shows a user interface for interacting with a suspension system of a vehicle according to an example; Figure 1 and Figure 2 a suspension system of a vehicle according to an example;

[0027] Figure 4 shows a user interface for interacting with a suspension system of a vehicle according to an example; Figure 1 and Figure 2 a suspension system of a vehicle according to an example;

[0028] Figure 5 shows a process flow diagram of a method of facilitating modification of a suspension system of a vehicle according to an example, including estimating roughness of a surface traversed by the vehicle;

[0029] Figure 6 shows a process flow diagram of a method of facilitating modification of a suspension system of a vehicle according to an example, including modifying a height adjustment tolerance of the vehicle;

[0030] Figure 7 shows a process flow diagram of a method of changing suspension settings according to an example;

[0031] Figure 8 shows a correction strategy for suspension leveling correction of a vehicle according to an exemplary method;

[0032] Figure 9 shows an exemplary correction strategy for suspension leveling correction of a vehicle according to an example;

[0033] Figure 10 shows a process flow diagram of a method of adjusting a body height of a suspension system of a vehicle;

[0034] Figure 11 shows a process flow diagram of a method of equalizing air spring pressure in a suspension system of a vehicle according to an exemplary instance;

[0035] Figure 12 shows a control strategy for addressing overcorrection of an air suspension system of a vehicle according to an exemplary method;

[0036] FIGS. 13A, 13B, and Figure 13C each shows a strategy for reducing activity of a suspension leveling system (e.g., in a vehicle) according to a respective exemplary method;

[0037] Figure 14 shows a process flow diagram of a method of adjusting a body height of a suspension system of a vehicle according to an exemplary instance;

[0038] Figure 15 A schematic view of a vehicle having an over-constrained air suspension system is shown;

[0039] Figure 16A A schematic view of a vehicle having unequal load distribution on the front and rear wheels and corresponding air suspension pressures is shown;

[0040] Figure 16B A process flow diagram of a method of adjusting the ride height of a suspension system of a vehicle according to an example embodiment is shown; Figure 16A

[0041] Figure 17A A chart showing ride height selection versus vehicle speed in a "General" ride height control mode according to an example embodiment is shown;

[0042] Figure 17B A chart showing ride height selection versus vehicle speed in an "Eco" ride height control mode according to an example embodiment is shown;

[0043] Figure 17C A chart showing ride height selection versus vehicle speed in a "Sport" ride height control mode according to an example embodiment is shown;

[0044] Figure 17D A chart showing ride height selection versus vehicle speed in a "Sport Launch" ride height control mode according to an example embodiment is shown;

[0045] Figure 17E A chart showing ride height selection versus vehicle speed in an "Off-road Auto / Rock Crawl" ride height control mode according to an example embodiment is shown;

[0046] Figure 17F A chart showing ride height selection versus vehicle speed in an "Off-road Drift" ride height control mode according to an example embodiment is shown;

[0047] Figure 17G A chart showing ride height selection versus vehicle speed in a "Towing" ride height control mode according to an example embodiment is shown;

[0048] Figure 18 A process flow diagram of a method of setting a vehicle speed limit in response to a suspension system height input according to an example embodiment is shown;

[0049] Figure 19 A process flow diagram of a method of adjusting a vehicle suspension height to facilitate easy entry into a vehicle according to an example embodiment is shown;

[0050] ​Figure 20 A process flow diagram showing a method of adjusting a vehicle suspension height to provide load leveling in accordance with an example embodiment is shown in FIG. 6. Figure 19 A process flow diagram showing a method of adjusting a vehicle suspension height to provide load leveling in accordance with an example embodiment is shown in FIG. 6.

[0051] Figure 21 A process flow diagram showing a method of adjusting a vehicle suspension height to provide load leveling in accordance with an example embodiment is shown in FIG. 6.

[0052] Figure 22 A process flow diagram showing a method of facilitating modification of a suspension system of a vehicle including selecting and / or changing control parameters is shown in FIG. 7. DETAILED DESCRIPTION

[0053] As will be further described below, in at least some example methods, the roughness of a road, surface, track, etc. can be estimated based on the vertical displacement of the wheels from an expected or neutral position over time or as the vehicle traverses the road, surface, track, etc. When driving on a very smooth surface (e.g., a paved road), the vehicle wheels can tend to experience minimal vertical movement. However, on a rough surface (e.g., a gravel road, a track, or any off-road environment), the surface / road input will drive the wheels to move a greater vertical displacement from their neutral position. It should be appreciated that reference to "road" roughness or surface encompasses not only paved road surfaces, but also unpaved roads, gravel, dirt, or any off-road environment.

[0054] An exemplary roughness metric can be determined using a function or algorithm that generally attempts to quantify the road inputs experienced by the wheel over a distance as a proxy for surface roughness. The quantified roughness can be used to influence the operation of the suspension, for example, by setting or changing control tolerances in response to changes in roughness. Thus, exemplary vehicles, suspension systems, and methods can involve determining a roughness metric of the surface being traversed by the vehicle based on body height measurements, and setting height adjustment parameters (e.g., tolerances) of an air suspension system based on the roughness metric. As will be discussed further below, in some exemplary methods, an estimate of the surface “flatness” can be used in conjunction with an estimate of the roughness to facilitate changes to suspension adjustment parameters that are appropriate for the surface conditions. For example, estimates of roughness and flatness can be used to desensitize a vehicle suspension system such that there are fewer and / or less significant changes in body height when the surface being traversed by the vehicle is relatively rough or uneven. The vehicle and / or suspension system can have a controller or module configured to facilitate modifications to the suspension system based on the determined height adjustment parameters. For example, height adjustment can be facilitated by changing tolerances associated with controlling the height or displacement of one or more springs (e.g., air springs of the vehicle). In some exemplary methods, the gain of the controller can be changed to adjust the tolerances, for example, increasing the tolerances when a rough surface is detected and / or when the surface induces a twist in the vehicle suspension. As will be discussed further below, in situations where corrective action can be difficult to implement or can result in errors, for example, when the vehicle wheels are moving rapidly over a relatively rough surface over time, or when an uneven surface induces a relatively large twist in the suspension, the vehicle can correspondingly reduce or prohibit body height changes or methods of changing for body height changes.

[0055] In other exemplary methods, the vehicle suspension system can employ different control methods in an attempt to allow for visual diagnosis of a misinstallation or servicing of the vehicle. For example, as will be described further below, when the vehicle is in a servicing or manufacturing setting, the vehicle can employ a relatively more precise control method using independent height control at each corner / wheel / air spring of the vehicle. When the vehicle is not in such a servicing / assembly condition, a relatively less precise control method can be used.

[0056] As discussed further below, in some example methods, the vehicle, its controller, or the method can involve detecting a suspension operating condition or operating environment of the vehicle, and changing a setting associated with the suspension system based on the suspension operating condition / environment. By way of example only, the suspension operating condition can include a ground angle, a vehicle steering angle, a vehicle speed, a suspension calibration condition, or an ambient temperature, as will be discussed further below. The setting associated with the suspension system can include, for example, a height change limit, a vehicle speed limit, a height change precision or tolerance, a level of axle height adjustment independence, a height adjustment threshold, or a suspension activity.

[0057] Now turning to Figure 1 and Figure 2 is shown and described in further detail, having a suspension system 101 that allows for control of the vehicle body height, as can be used in connection with various example instances herein. The vehicle 100 can be a battery electric vehicle, for example, having one or more electric motor generators driven with electrical power supplied from a battery pack (not shown). In Figure 1 is shown, the pneumatic and electrical connections between components of the vehicle 100 according to example methods discussed below are shown. In Figure 2 is shown, having the same pneumatic connections as shown in Figure 1 is shown, having the same pneumatic connections as shown in Figure 1The air springs 104 each at a designated corner of the vehicle 100, for example, function as a compliant element in the suspension of the vehicle 100. In addition to the compliance of the air springs 104, a shock or damper (not shown) can be provided at each vehicle wheel to absorb mechanical energy imparted to the wheel by bumps or undulations on the surface traversed by the vehicle 100. Further, the air springs 104 can be configured to raise or lower the ride height of the vehicle 100. More specifically, each air spring 104a, 104b, 104c, and 104d can raise or lower the respective corner height of the vehicle 100. As will be seen in further detail below, the vehicle dynamics module 102 can implement changes in ride height via the air springs 104, with each air spring raising the associated corner height in the vehicle 100. In some cases, the vehicle dynamics module 102 can automatically shift between different ride heights in response to vehicle conditions. In other cases, a user, such as a driver of the vehicle 100, can manually select different ride heights via a graphical user interface in communication with the vehicle dynamics module 102. The vehicle 100 can include one or more controllers, such as the vehicle dynamics module 102. The vehicle dynamics module 102 and other controllers disclosed herein can include a processor and / or a memory. An exemplary processor can be a hardware processor, a software processor (e.g., a processor emulated using a virtual machine), or any combination thereof. In some embodiments, the combination of a processor and a memory can be referred to as a control circuit of the vehicle 100. In some embodiments, a separate processor can be referred to as a control circuit of the vehicle 100. The memory can include a hardware element for non-transitory storage of commands or instructions that, when executed by the processor, cause the processor to operate the vehicle 100 according to the embodiments described above and below. For example, the memory can include a computer-readable or machine-readable medium. The control circuit can be communicably connected to components of the vehicle 100 via one or more wires or via a wireless connection.

[0058] The vehicle dynamics module 102 can be electrically communicated with the air compressor assembly 106, which generally controls the system air pressure. More specifically, an air storage volume can be housed within an air reservoir or canister 108. The air reservoir 108 can store pressurized air to maintain a reserve of aerodynamic energy that can assist the compressor 106 in raising the vehicle body height of the vehicle 100. A valve block assembly 110, actuated by the vehicle dynamics module 102, can be positioned between the compressor 106 and the air springs 104 and can be configured to facilitate airflow between components of the vehicle 100's suspension. For example, the valve block 110 can control the supply of air and / or aerodynamic energy from the air reservoir 108 to the air springs 104. The valve block assembly 110 can also facilitate the release of air pressure from the air springs 104. Each air spring 104 can be controlled independently, for example, via the valve block 110. For example, the valve block 110 can have a plurality of valves 111 corresponding to each air spring 104 and canister 108 (see...). Figure 2 The compressor 106 can be controlled by the vehicle dynamics module 102, for example via the compressor relay 114 and via temperature sensing and valve control input to the air compressor assembly 106. As will be described in further detail below, the angular height or displacement of the air spring 104 can be controlled based on any appropriate control parameters. In one exemplary method, displacement control can be used to implement control of the air spring 104, wherein air can be added to / removed from the air spring 104 based on a target displacement of the air spring 104 and / or the corresponding angular height of the vehicle 100. For example, in the case of a desired displacement of the air spring 104, the actual / measured displacement or corresponding angular height of the vehicle 100 is measured and compared with the target displacement / height, wherein air is added to / removed from the air spring 104 accordingly. In another exemplary method, air quality control can be used to control the air spring 104, wherein air can be added to / removed from the air spring 104 based on a target air quantity or mass. For example, in the case of a desired displacement of the air spring 104, the corresponding air mass corresponding to the desired displacement and / or turning angle height of the vehicle 100 is determined, wherein air is added to / removed from the air spring 104 to achieve the target air mass of the air spring 104. In yet another example, depending on the surface and / or vehicle 100 conditions, displacement control and air mass control may be selectively employed, as will be discussed further below.

[0059] The vehicle 100 can also include body height sensors 112a, 112b, 112c, and 112d (collectively, 112), each configured to measure a vertical displacement between a corresponding wheel and the vehicle 100. The suspension system of the vehicle 100 can generally automatically level the vehicle 100, and via adjustment of the air springs 104, for example, in response to one or more heights measured by the body height sensors 112, to change a body height of the vehicle 100. Thus, when the vehicle 100 is carrying a relatively heavy load in the rear cargo area, the rear body height sensors 112c, 112d can detect that the vehicle height has been lowered. In response, the vehicle 100 can increase the internal air pressure in the rear air springs 104c, 104d to level the vehicle 100.

[0060] In exemplary instances herein, as will be described in further detail below, the vehicle 100 can change a height adjustment parameter (e.g., a tolerance setting of an automatic leveling system or another suspension parameter, or change a body height) in response to, for example, the vehicle 100 detecting that a relatively rougher surface is being traversed. For example, the vehicle dynamics module 102 or other controller of the vehicle 100 can be configured to increase a height adjustment tolerance in response to an increase in a roughness measure of a road surface. Additionally, the vehicle 100 can decrease a height adjustment tolerance in response to detecting a decrease in a roughness measure of a road surface. As will be described in further detail below, in some exemplary methods, the surface or roughness measure is based on a change in a corner height error. As used herein, a corner height error is defined as a difference between an expected body height and an actual / measured body height, which can be determined by the sensors 112. Further, in some examples, the roughness measure takes a moving average of the corner height error over a given window or period of time. While the examples herein generally relate to changing a tolerance of an automatic leveling of the suspension system of the vehicle 100, any other suspension parameter that is appropriate can also be adjusted in response to detecting a change in roughness. Thus, to the extent that a suspension parameter is adjustable by the vehicle 100 and can be affected by a change in roughness of a surface traversed by the vehicle 100, the vehicle 100 can adjust that parameter in response to detecting a change in roughness. By way of example only, a suspension damping setting, such as a damper compliance / stiffness, can be adjusted in response to a change in roughness, for example, increasing compliance in response to an increase in roughness and / or decreasing compliance in response to a decrease in roughness.

[0061] A user can select various drive, suspension, or vehicle modes that can affect the performance of the air suspension components. For example, as shown in FIGS. 1 1 A and 1 1 B, one or more user interfaces can generally be provided for selecting a drive mode. Figure 3 and Figure 4 As shown in FIGS. 1 1 A and 1 1 B, one or more user interfaces can generally be provided for selecting a drive mode. Figure 3user interface 300 and Figure 4 user interface 400 can each provide a screen or menu to the driver or other vehicle occupant, for example, via a touchscreen. As shown in Figure 3 a vehicle 100 is represented with a vehicle body height represented relative to a ground 302. Similarly, in Figure 4 a vehicle 100 is represented with a vehicle body height represented relative to another ground 402. The user interfaces 300, 400 can be in communication with the vehicle dynamics module 102 to effect changes to the vehicle 100 or components of the suspension of the vehicle 100. By way of example only, various drive modes can affect the air suspension vehicle body height, for example, by raising or lowering the vehicle 100, by changing the compliance of the air springs 104 or dampers / shock absorbers of the vehicle 100, etc. As shown in Figure 3 the vehicle 100 includes a general mode, a sport mode, an off-road mode, a tow mode, and an economy (eco) mode, each of which is displayed in the user interface 300 for selection. Upon selection of one of the modes in the user interface 300, a plurality of sub-modes can be displayed. For example, upon selection of the off-road mode in the user interface 300, as shown in Figure 4 the automatic sub-mode, rock crawl sub-mode, rally sub-mode, and drift sub-mode can be displayed in the user interface 400 for selection. One or more suspension or vehicle parameters can be displayed in conjunction with the modes and sub-modes included in the user interfaces 300, 400. By way of example only, different vehicle body heights can be implemented under the vehicle modes and sub-modes, as will be further discussed below. Additionally, as will be further described below, there can be multiple vehicle body heights available within each of the modes and / or sub-modes, as will be further described below, the vehicle body heights can be customized for each of the given modes or sub-modes to achieve desired performance characteristics of the vehicle 100.

[0062] Turning now to Figure 5Fig. 5 further illustrates and describes an exemplary process 500 for determining a roughness metric. Process 500 can generally be employed when the vehicle is moving, and thus, process 500 can for example confirm or query that the vehicle 100 is in motion using the vehicle dynamics module 102, and then employ process 500 to determine a roughness metric. It should be noted that alternatively, a previously determined roughness can be stored in the vehicle's non-volatile memory, which can be used as an initial value for the estimator if the estimator does not have any opportunity to calculate before the suspension is required to operate. This can be useful, for example, for the case where the vehicle is parked on a rough surface, such that the roughness is taken into account when the vehicle is subsequently used, thereby avoiding the vehicle suspension from being overly active due to the rough surface. As input to process 500, a corner height error for one or more wheels of the vehicle 100 can be determined. In exemplary process 500, the measurement is made based on signals received from four sensors 112, each of which is positioned at a respective wheel of the vehicle 100. Other numbers of sensors and wheels are possible in other exemplary approaches. Generally, the corner height error can be determined based on a difference between an expected or target height and an actual height (e.g., as measured by the body height sensor 112). The appropriate expected or target height can be determined in any manner. By way of example only, the target can be a desired body height for the off-road mode of the vehicle 100, e.g., 11.5", or a target corner height for one or more air springs 104. The target height for a particular corner or location of the vehicle (e.g., where the air spring 104 is positioned) can vary dynamically as the vehicle moves. Thus, the target height can be adjusted to account for factors such as acceleration, deceleration, turning, pitch, roll, etc. In examples, the sensors 112 are displacement sensors that measure displacement of the wheels from the vehicle 100, although wheel accelerometers or the like can also be used in other examples.

[0063] At block 505 of the process 500, the vehicle dynamics module 102 can convert the corner height error into a delta or change in the corner height error measurements over a given time period. Initially, it should be appreciated that the vehicle dynamics module 102 can typically have some non-zero amount of height error at all times, which results in a DC offset. As described in further detail below, the DC offset generally refers to a physical offset error in the measurements, and can be produced by a number of sources (e.g., a curved sensor arm, an asymmetrically loaded vehicle, etc.). To prevent this DC offset from being considered a road / surface input, the process 500 can remove the DC offset from the corner height error measurements. Further, at block 505, it can also be desirable to remove the effects of pitch or roll of the vehicle, or other generally constant inputs to the suspension that are not caused by roughness. For example, in the case where the vehicle 100 is leaning to the passenger side as it traverses a left-hand bend, there can be a corner height error due to the vehicle leaning, but this effect is not caused by roughness. In contrast, in the case where the vehicle 100 is traversing a rough surface, the corner height error at the wheels of the vehicle 100 can rapidly change as the wheels bounce up and down. Thus, the process 500 can convert the input corner height error into a delta or change in the corner height error over time. In doing so, the vehicle dynamics module 102 can generally remove more static effects caused by non-road roughness effects. Thus, the result of block 505 can be a “corner surface input” at each air spring 104 and / or wheel.

[0064] Proceeding to block 510, the process 500 can determine a road or surface input magnitude, for example, by summing the absolute values of the corner surface inputs determined at block 505. Thus, the process 500 does not know whether the surface / road input is positive or negative (i.e., whether the rough surface is driving the wheels up or down), and simplifies the surface input by determining the absolute values of the changes in the individual corner height errors and summing them together. The process 500 can then proceed to block 515.

[0065] At block 515, a speed-dependent moving average filter can be applied to the surface input values. Generally, instantaneous measurements of surface input values can be very noisy signals. For example, road surface roughness can be obtained by applying a speed-dependent moving average filter in an attempt to normalize road length measurements. For example, the filter time constant can be scaled with vehicle speed to achieve different behavior at low speeds versus high speeds. For example, at relatively low speeds, a smaller time constant can be used because at low speeds it can be desirable for the roughness estimate to emphasize the terrain that the vehicle 100 has just traversed. In other words, it can be desirable to interpret a single event, such as a curb strike or a rock crawl, as a relatively rough surface and reduce the range in which leveling events can occur. By way of example only, such a smaller time constant can be used for a rock crawl or parking over a curb in a congested parking lot. In contrast, a relatively larger time constant can be used at higher speeds because at such times the roughness estimate can tend to have less noise but more closely approximate the general roughness of the road surface (as opposed to discrete low speed events or inputs, e.g., rock crawl is typical). The relatively larger time constant can be used to reduce the impact of a single input at relatively high speeds that can otherwise be less meaningful when the surface is relatively smooth and, thus, leveling events can be more desirable at such higher speeds. Any filter device or filtering method can be employed. In an example, a first order low pass infinite impulse response (IIR) filter can be employed, outputting an exponentially weighted moving average filter. After block 515, the process 500 can have surface input values over a previous time window.

[0066] Proceeding to block 520, the process 500 can apply a speed-dependent gain determination to determine a final roughness estimate, e.g., as a percentage. The gain of this determination can be speed-dependent, with similar principles as the filter time constant of block 515. Thus, a relatively larger gain can be employed at lower speeds and a smaller gain can be employed at higher speeds. In this way, individual wheel position shifts at lower speed events, e.g., as driving over a curb, are treated as very rough road. In another example, a 40 millimeter (mm) shift can be observed on one wheel at a vehicle speed of 20 kilometers per hour, which is treated as very rough road from the perspective of the body height controller (i.e., the vehicle dynamics module 102). In contrast, at higher speeds, a relatively smaller gain can be applied because it can be desirable for the roughness metric to capture larger wheel shift events but ignore smaller events that are common at high speed travel even on relatively smooth surfaces. After determining the roughness metric, the process 500 can terminate.

[0067] In some exemplary instances, vehicle 100 may be configured to select various modes in response to detected conditions. In some examples, vehicle 100 selects a height accuracy mode that facilitates changes to (a) the control tolerance associated with a change in vehicle height and / or (b) the height axle control mode associated with the method used to control the change in vehicle height. For example, the height accuracy mode may be modified to increase or decrease the accuracy of the change in vehicle height. A height accuracy mode may be selected from multiple height modes. Exemplary height modes may include height precision modes, such as a nominal accuracy mode and a maintenance accuracy mode, wherein the change in vehicle height is performed with a greater accuracy and / or a smaller control tolerance than the nominal accuracy mode. Alternatively or additionally, the height mode may include multiple height axle control modes that vehicle 100 may employ in response to detected conditions. In the examples herein, the height axle control mode may include an average axle control method, wherein the suspension height adjustment is based on the average of two vehicle heights determined at a single axle of the vehicle. Alternatively, in other cases, vehicle 100 may employ an independent axle control method, wherein a first height adjustment and a second height adjustment are performed independently at the first wheel and the second wheel of the vehicle's axle. Vehicle 100 may select an axle control mode in response to the detection of a maintenance / manufacturing environment or other detected conditions, as will be discussed further below.

[0068] When the vehicle is stationary, as described above and Figure 5 The values ​​of the exemplary roughness measurements shown typically do not change. If the vehicle stops and closes relatively quickly after entering the lane, the process of the vehicle crossing the curb to enter the lane and then stopping almost immediately may cause the vehicle to perceive itself as having parked on a “rough” surface upon restarting. To correct for this potential problem and facilitate appropriate changes to the suspension height adjustment parameters, it may be useful to consider the “flatness” of the surface the vehicle traverses.

[0069] As used herein, “flatness” refers to the absence of twist between different wheel axles of a vehicle (e.g., between a front axle and a rear axle of the vehicle). Thus, a surface on which a vehicle is parked can be considered a surface that is completely “flat” if the left / right displacements of the front and rear axles are the same, i.e., the vehicle is “tilted” the same amount in the same direction at the front and rear axles (or when both axles are zero tilt). In contrast, a surface that has undulations between the front and rear axles causes the front vehicle suspension to “tilt” toward one side, and the rear vehicle suspension to induce a “twist” in the vehicle, and the surface is relatively less “flat” with respect to the vehicle. Thus, in some example methods, a suspension system, vehicle, or associated method can determine an amount of twist of the suspension system, and determine a height adjustment parameter based on the twist. In at least some examples, the twist can be used in combination with other metrics (e.g., roughness) to determine the height adjustment parameter. As described further below, example instances for determining twist can include determining a difference between a first lateral displacement difference of a front axle of the vehicle and a second lateral displacement difference of a rear axle of the vehicle.

[0070] If a vehicle is on a surface that causes a twist in the suspension between the front and rear axles / wheels, difficulties in vehicle suspension height adjustment can result, particularly if the average axle control method mentioned above is employed. More specifically, if the change in height is controlled based on the average displacement of the two air springs 104 at opposite sides of a single axle, when the vehicle is tilted in opposite directions at the front / rear axles, one side of the vehicle will tend to exceed the body height target, while the opposite side of the vehicle will tend to not reach the body height target. Thus, in some examples, an independent control method (i.e., each of the four wheels / air springs is controlled independently) can be employed in response to determining that the vehicle is on a relatively uneven surface or that the vehicle suspension is experiencing at least a threshold amount of twist. Additionally, the change in height can be limited when the vehicle is on a surface that causes a threshold amount of twist in the vehicle suspension. It should be noted that the measurement of flatness is generally not dependent on dynamic movement of the vehicle and / or suspension, so the measurement of flatness does not lose relevance when the vehicle is stationary. In contrast, roughness metrics can be less relevant when the vehicle is stationary, as they are determined based on movement of the suspension / vehicle over time or as the vehicle traverses a surface. Thus, the flatness measurement can provide useful information for a vehicle suspension system to determine whether / when to reduce the change in height correction, particularly at very low speeds or when the vehicle is stationary.

[0071] In an example, twist can be defined as having no flatness, and twist can be quantified by the difference between the lateral or side-to-side displacement differences of the two axles of the vehicle. The twist in the suspension can be based on the difference between (1) a first lateral displacement difference of the front axle of the vehicle and (2) a second lateral displacement difference of the rear axle of the vehicle. In one example, twist is calculated by:

[0072] (FL Displacement - FR Displacement) - (RL Displacement - RR Displacement) = Twist

[0073] where:

[0074] FL Displacement = displacement of the left front air spring;

[0075] FR Displacement = displacement of the right front air spring;

[0076] RL Displacement = displacement of the left rear air spring; and

[0077] RR Displacement = displacement of the right rear air spring.

[0078] In other words, the displacement difference between the left front and right front air springs and the displacement difference between the left rear and right rear air springs can be compared to determine twist. When both the front and rear axles of the vehicle are tilted or roll the same amount in the same direction (or are both level), the twist will typically be zero, and the underlying surface can be considered “flat.” The above calculation provides a measure of the twist or diagonal load of the vehicle. In an example, a filtered signal for each of the displacement measurement results can be employed.

[0079] As will be further described below, the above-described measurements of flatness or twist can be used in the context of the vehicle 100 in at least several ways described herein. First, a height change request can be denied if the surface induces a certain amount of twist in the vehicle (or, in other words, if the surface is not flat to a certain degree). Additionally, the vehicle 100 can use independent axle control methods (rather than average control) in response to a determined flatness metric. More specifically, average axle control can result in asymmetry in the vehicle’s travel if the surface is not flat, as described above. Moreover, the vehicle 100 can determine a desensitization factor to apply in response to a determined flatness metric to avoid or reduce the impact of a body height change or leveling event.

[0080] In at least some example instances, the vehicle 100 can determine the surface condition based on a flatness and roughness metric of the surface, with one or both of these factors being used to determine or adjust the height adjustment parameter. As noted above, the flatness or twist can be determined based on a static displacement measurement of the air spring 104, and thus can provide useful information when the vehicle 100 is stopped or at very low speeds. In contrast, the roughness metric as described above is determined based on movement of the air spring 104 and / or other components of the vehicle 100 over time. Thus, in some example methods, the flatness and roughness are emphasized or de-emphasized based on the speed of the vehicle 100. For example, when the vehicle 100 is moving, the roughness metric can be relied on to a greater degree (or any consideration of flatness / twist is excluded), while when the vehicle 100 is stationary or at very low speeds (e.g., below 5 miles per hour (mph)), the flatness / twist is relied on to a greater degree (or any consideration of roughness is excluded). Thus, in some example methods, the height adjustment parameter can be initially determined based on roughness, e.g., when the vehicle is in motion, and then subsequent height adjustment parameters are determined based on twist, e.g., when the vehicle speed drops to zero or below a speed threshold. Further, a context switch can be used to determine a desensitization factor used with respect to the suspension height adjustment parameter. For example, if the height is known to be accurate when the speed of the vehicle 100 is above zero, then desensitization can be applied when the vehicle is stopped / stationary (e.g., to reduce the intervention of height change corrections). On the other hand, if the height measurement is known to be less accurate when the vehicle 100 is moving (i.e., the vehicle speed is above zero), then desensitization can be applied based on (only) the determined flatness / twist.

[0081] Referring now to Figure 6 An example process 600 for determining a height adjustment parameter, e.g., to adjust the tolerance of a vehicle suspension of a vehicle 100, is shown and described in further detail. The height adjustment parameter can be used to facilitate modification of the suspension. The process 600 can begin at block 605, where a surface condition can be determined. The surface condition can include a roughness characteristic (e.g., as set forth above by a roughness metric) and / or a flatness characteristic (e.g., as set forth above by a suspension twist). For example, upon detecting that the vehicle 100 is in motion or turning on a controller, the vehicle dynamics module 102 can determine a roughness metric of a surface being traversed by the vehicle 100 based on a body height measurement and / or a measurement of the suspension twist. In examples, block 605 employs the process 500 to determine the roughness metric and the measurement of the suspension twist set forth above. The process 600 can then proceed to block 610.

[0082] At block 610, the process 600 queries whether a change in surface conditions has occurred, e.g., based on the roughness metric and / or suspension twist determined at block 605. In some examples, the query at block 610 obtains a positive result only when at least one of the roughness metric or twist changes by at least a threshold amount or percentage. Thus, the vehicle 100 can be prevented from changing suspension settings or body height adjustment tolerances in response to small changes in terrain. In the event that block 610 obtains a positive result, the process 600 can proceed to block 615, where the height adjustment parameters, e.g., the height adjustment tolerance, can be modified according to the change in surface conditions. Thus, subsequent adjustments to the body height can be affected, e.g., via adjustments to the air springs 104. Alternatively, if block 610 obtains a negative result, the process 600 returns to block 605. Thus, the process 600 can generally monitor surface conditions continuously during operation of the vehicle 100.

[0083] For example, an exemplary roughness metric, as determined using the processes 500 and / or 600, can be used to scale or adjust the height adjustment of the vehicle 100, e.g., the height adjustment tolerance of the leveling feature of the vehicle 100. Further, the tolerance adjustment can be performed according to performance expectations or expectations for the vehicle 100. As just one example, the vehicle 100 can adjust the tolerance more significantly in the sense that the vehicle 100 is designed for off-road or other non-road surfaces that are expected to be rough. Generally, the degree and / or frequency of height adjustment of the vehicle suspension can be reduced in the event of a relatively greater roughness metric as compared to a relatively smoother road or smaller roughness metric. Further, the roughness metric can be used to reduce the degree of a requested adjustment of the suspension components or suspend the adjustment entirely in the sense that a vehicle occupant or driver requests a change in the suspension. As just one example, a relatively tighter height adjustment tolerance of 2 mm can be used to control the vehicle body height when the vehicle 100 determines that the roughness is below a predetermined threshold (i.e., indicating a relatively smooth ground surface), while a relatively greater height adjustment tolerance of 5 mm can be employed when the vehicle 100 determines that the ground surface traversed by the vehicle 100 is above a predetermined threshold (i.e., indicating a relatively rougher ground surface).

[0084] Modifications to the suspension system 101 of the vehicle 100 can be facilitated by, for example, changing tolerances, control parameters, or control methods, as further described in the example processes or systems herein. By way of example only, modifications can be facilitated by sending instructions to control various aspects of the suspension system 101 by one or more controllers, electronic control units (ECUs), or the like, of the vehicle 100. For example, the vehicle dynamics module 102 can send software instructions to adjust values or types of control targets, such as air mass, displacement, pressure, or other mechanical aspects of the air springs 104 and / or other components of the suspension system 101. Modifications to the suspension system 101 of the vehicle 100 can be performed in any manner appropriate. In an example, modifications to the suspension system 101 of the vehicle 100 can be performed by implementing a height change parameter, for example, to change a tolerance associated with height changes, such as by adjusting a gain of a controller. In another example, modifications to the suspension system 101 of the vehicle 100 can be performed by changing a height axle control method or mode of the suspension system 101, for example, by switching from a uniform axle control method to an independent axle control method or vice versa. In yet another example, modifications to the suspension system 101 can be performed by changing a control parameter for height changes, for example, from displacement control to air mass control or vice versa.

[0085] Example roughness metrics as determined herein can provide benefits beyond load leveling aspects of a vehicle suspension system. For example, it can be beneficial to record or store roughness observed by a given vehicle over time. Further, in the sense that roughness metrics can prove an abnormal event or condition of a vehicle, the metrics can be broadcast from the vehicle to provide notification of the vehicle condition. Additionally, as noted above, other vehicle systems can also employ roughness metrics, such as adaptive damping controllers of a vehicle, which can change damping characteristics of a vehicle suspension.

[0086] As noted above, in some example methods, the vehicle 100 can be configured to facilitate identifying a misaligned or misconfigured suspension of a vehicle in certain environments. In examples, a controller, such as the vehicle dynamics module 102, is configured to determine that the vehicle is in a service environment, and set a height accuracy mode of the suspension system based on determining that the vehicle is in the service environment. The controller can also be configured to identify an optimal mode of the plurality of height accuracy modes based on the suspension system operating conditions / environment (e.g., detecting that the vehicle is in a service environment), and modify the suspension system to be in the determined height accuracy mode. In examples herein, a service environment can include a service location, such as a manufacturing facility or vehicle assembly facility, or a vehicle dealership or service station. For example, the service environment can be detected by using a notification provided to the vehicle 100 or its controller by a service personnel, such as by setting a flag identified by the vehicle dynamics module 102 to indicate that the vehicle 100 is in a service environment. In another example, the service environment can be detected by the vehicle automatically detecting proximity of sensors associated with a service environment. In another example, GPS coordinates of the vehicle can match known service locations associated with a vehicle manufacturer. Thus, in these examples, the vehicle 100 can be automatically notified of a service environment. Since examples herein generally involve identifying and correcting suspension system adjustments, in at least some examples, a service environment can be identified in the sense that the environment is capable of performing suspension system adjustments, e.g., these environments have appropriate tools, trained personnel, etc., to correct problems or malfunctions of the suspension system or components thereof of the vehicle 100.

[0087] It should be noted that detection of a service environment need not be implemented immediately for adjustments to the vehicle suspension to be made. For example, the vehicle can implement changed adjustments when the vehicle is being serviced, as opposed to merely parked in a parking lot (e.g., when a customer initially arrives). In examples, a service personnel can place the vehicle in a service mode, or an ECU or controller of the vehicle 100 can detect that the vehicle is within a threshold proximity of a service machine (e.g., a lift, a service computer, etc.) to cause the suspension system 101 of the vehicle to be adjusted. In another example, the vehicle 100 can detect proximity to a service center, dealership, etc., and make a service mode of the vehicle 100 available to a driver or service personnel in response to the detection. In other examples, the vehicle 100 can implement changes regardless of whether the vehicle 100 is being serviced. In this way, if the vehicle 100 is placed in a service environment, e.g., at a dealership, for some other reason, the vehicle can automatically initiate adjustments to make potential problems (e.g., a suspension component that is not up to par) more apparent to service personnel trained to notice and / or correct the problems.

[0088] Reference is now made to Figure 7An exemplary process 700 for changing suspension settings is shown and described in further detail. At block 705, the process 700 queries whether a height change is required. If no height change is required, the process 700 can return to block 705 to monitor for any required height changes. In the event a height change is required, the process 700 proceeds to block 710.

[0089] At block 710, the process 700 queries whether the vehicle 100 is in an environment requiring high accuracy of leveling adjustment, such as a service environment or a manufacturing environment. As noted above, in one example, the vehicle 100 can set a service or manufacturing flag that is activated by a service or manufacturing personnel, detected by the vehicle 100 that it is in / near a service environment, or otherwise for a period of time (e.g., 24 hours) in any manner described herein. If block 710 determines that the vehicle is in a service / manufacturing environment, the process 700 can then proceed to block 715.

[0090] At block 715, a high accuracy mode of the air suspension leveling system can be implemented relying on independent control of each air spring 104. In this manner, leveling adjustments can generally be made with relatively greater accuracy, facilitating identification of problems caused by mis-installed components. As one example, in the event that a suspension bushing is over-torqued during installation or service, the relative increase in vehicle corner load caused by the vehicle's leveling event and associated air springs 104 and / or wheels of the vehicle can evidence the problem. By increasing the accuracy of the suspension control system in such environments, the vehicle 100 can make leveling adjustments more aggressively, exacerbating any resulting corner load differences caused by leveling and underlying suspension conditions. Additionally, the process 700 can disable average axle control leveling at block 715, such that the height of each air spring 104 is adjusted independently. In this manner, corner load differences across the vehicle are more easily observed in addition to those observed between front / rear corner loads. The increased accuracy of the high accuracy mode and use of independent control of each air spring 104 can help identify the source of potential problems, such as by isolating particular wheels / air springs 104 of the vehicle 100 that are particularly heavy / light with respect to other corner loads.

[0091] In at least some examples herein, the vehicle 100 includes multiple height accuracy modes having different corresponding control tolerances. For example, in addition to the high accuracy mode of the air suspension leveling system, a low accuracy mode (relative to the high accuracy mode) can be used in other situations / settings, as will be discussed further below.

[0092] In the event that the vehicle is not determined to be in a service or manufacturing environment at block 710 (or, in other words, other environments where high precision control of leveling is not necessary), the process 700 can proceed to blocks 720-730, where a reduced precision control method is used for height changes. For example, a lower precision control method (e.g., a 5 mm height adjustment tolerance, as opposed to a high precision height adjustment tolerance of 2 mm) can prevent the vehicle 100 from overcorrecting itself in automatic leveling.

[0093] At block 720, the process 700 queries whether the determined height change at block 705 is the result of an automatic leveling event (i.e., the vehicle 100 automatically corrects in response to loading the rear or a side of the vehicle) or a high articulation event. A high articulation event can be defined as a single wheel movement or articulation, i.e., a single wheel articulation that exceeds a predetermined relative articulation threshold. A relative high articulation event can be indicative (i.e., where the suspension moves more than a predetermined minimum value or a predetermined relative articulation threshold) of off-road operation or other extreme input to the vehicle suspension, by way of example only. In either case, it can be desirable to employ independent control of each air spring 104 and / or associated wheel. More specifically, conditions that give rise to a need for an automatic leveling event cannot be assumed to be equally applicable to the driver and passenger sides of the vehicle 100, for example, the vehicle has been reloaded on the driver side of the rear cargo area, and thus it is desirable to ensure that the vehicle 100 is level on both sides. Additionally, a high articulation event can also warrant independent control of the air springs 104 and / or wheels. In the event that it is determined at block 720 that there is one of a leveling event or a high articulation event, the process 700 can proceed to block 725. At block 725, the vehicle 100 employs a normal precision, independent control method, where the control tolerance of adjustment is within normal parameters. In an example, the relatively lower precision of the normal precision control method (e.g., within 5 mm of a target position, as opposed to within 2 mm of a target position for high precision control) is configured to prevent the vehicle 100 and / or suspension system from overcorrecting when correction can not be necessary. It should be noted that in response to the reduction in control tolerance, the average axle control can be disabled at block 725 (e.g., as described above at block 715), such that the vehicle 100 employs independent control.

[0094] Alternatively, if the process 700 determines at block 720 that neither a leveling event or a high articulation event is urgently requiring a height change, the vehicle 100 can employ an average axle control method, and the process proceeds to block 730. Accordingly, the vehicle height is adjusted based on the average adjustment required measured at each wheel on a given axle. For example, the average axle control method can be useful where a height change is initiated by a new selection of a drive mode or driving mode change (e.g., selection of an off-road mode that increases the vehicle's ground clearance). In these cases, changes between the two sides in the vehicle 100 are less likely to result in a height change. Accordingly, the average axle method generally prevents adjustments between the two sides of the vehicle 100 in situations where an adjustment is not warranted. Generally, using the average axle control adjustment can more easily achieve equal corner loads, which can result in the best vehicle settings for dynamic behavior. Accordingly, the average axle control method can improve the vehicle's ability to adjust to the correct height more quickly when the driver requests a change, in the sense of prioritizing dynamic behavior.

[0095] Turning now to Figure 8 and Figure 9 a correction strategy for leveling corrections to the vehicle 100 is shown and described in further detail. Generally, the vehicle 100 can attempt to address a suspension correction condition associated with the suspension system 101. Merely by way of example, a change in the distribution of cargo, passengers, etc. in the vehicle 100 can cause the vehicle 100 to tilt between the two sides, or pitch toward the rear of the vehicle 100 ("sitting tail") or the front of the vehicle ("sagging nose"). The suspension correction condition can include such a tilt or pitch of the vehicle, which the vehicle 100 attempts to correct by adjusting the pressure of one or more air springs 104. In Figure 8 In the method shown, individual corner control (i.e., where each air spring 104 is controlled independently to a target height) can result in angularly symmetric corner loads due to the over-constrained system of the vehicle 100. In this example, the over-constrained system is a result of the vehicle 100 having four wheels and associated air springs 104, as three points define a plane, so an adjustment made to one of the four air springs 104 can affect the measured height and / or wheel load of one or more of the other air springs 104 and / or associated wheels. In Figure 15 An illustration of an over-constrained vehicle is provided in Figure 8In the depicted correction strategies, individual corner control (i.e., independent axle control methods) can be employed for leveling corrections, which are applied in response to pitch corrections, over / under or incomplete height corrections, and corner height corrections, while average axle control (i.e., where correction amounts determined for both wheels of a single axle are averaged, with each correction amount applied to the air spring 104 associated with both wheels of that axle) can be employed for body height changes. However, employing individual corner control in response to the indicated conditions can cause diagonal cornering loads. This can be exacerbated by increasing control precision, e.g., by reducing the tolerance for error in body height. In some cases, alignment ability is affected.

[0096] Accordingly, in Figure 9 exemplary examples of corrections that address Figure 8 the problems experienced in the depicted strategies. Generally, the methods depicted in Figure 8 in comparison to the methods depicted in Figure 9 the methods depicted in employ individual corner control only for incomplete corner height corrections (e.g., situations where average axle control cannot be used for an initial attempt). More specifically, individual corner control is permitted only for subsequent attempts to correct height. Accordingly, average axle control is used for body height changes, pitch corrections, over / under height corrections, and initial attempt corner height corrections or high precision corner height corrections. In other words, height corrections can initially be made using average axle control, with subsequent attempts using individual corner control (e.g., if the first attempt using average axle control is not sufficient to effectively reduce error). It should be noted that in some examples, the relatively high precision control mode (i.e., with a relatively small tolerance for body height error) is not employed during normal vehicle operation. Additionally, average axle control can be employed when the vehicle 100 determines that the vehicle is on a flat surface or that the twist level is relatively low, although individual corner control can also be employed. In this way, asymmetry caused by uneven surfaces can be reduced or eliminated. The same approach can be employed for pitch corrections, i.e., average axle control when the ground is flat or the twist level is relatively low, and individual corner control when the ground is relatively uneven (or the twist level is above a threshold). Individual corner control can also be applied instead of average axle control when corrections are made for relatively steep inclines or slopes (e.g., inclines or slopes above a predetermined value). Furthermore, in the exemplified examples, roll corrections can rely on individual corner control, as if average axle control is employed, vehicle 100 leaning to one side can introduce asymmetry.

[0097] It should be noted that in some examples, because air pressure is not equal on each axle, axle height adjustment control is performed independently on both axles of the vehicle. For example, as depicted in FIG. 1, the vehicle 100 includes a front axle 102 and a rear axle 104. In some examples, the front axle 102 is controlled independently of the rear axle 104.Figure 16A As shown, the internal pressure of the air springs 104 on different axles can vary, with a difference greater than the load distribution between the front and rear axles of the vehicle. More specifically, in the illustrated example, the vehicle is shown with a nearly balanced front / rear load distribution, i.e., the load on the front axle is slightly greater than 50%, and the load on the rear axle is slightly less than 50%. However, the air pressures on the front and rear axles differ more significantly. Therefore, it may be beneficial to independently control the height adjustment of the front and rear axles. More specifically, as... Figure 16B As shown in the exemplary process 1600, the vehicle may initially be in standby mode at block 1605. In response to a height increase request for the vehicle 100, such as a request for automatic or manual height increase by the vehicle driver, process 1600 may proceed to block 1610. At block 1610, the vehicle may initially raise the rear axle until the overall / desired height adjustment is achieved, or the permissible height difference between the axles is reached. If the permissible axle height difference limit is reached as the rear axle is raised, process 1600 may proceed to block 1615, where the axle has previously been raised to a height equal to that of the rear axle. Returning to block 1610, the rear axle can then be raised further. Therefore, process 1600 may iterate between blocks 1610 and 1615 as necessary to complete the height adjustment (i.e., if the permissible height difference between the axles is reached, process 1600 moves to block 1615, and if the front and rear heights are equal and the desired height is not achieved, it returns to block 1610). In this manner, the front and rear axles may be adjusted incrementally in an alternating manner until the height adjustment is complete, and process 1600 then returns to block 1605. Therefore, in some examples, the vehicle dynamics controller 102 can implement height changes at two different axles (i.e., front / rear axles) within an axle height difference limit. More specifically, a first height change is initiated at the first of the two axles (e.g., the rear axle) until the axle height difference limit is reached. Subsequently, a second height change can be initiated at the second of the two axles (e.g., the front axle) until either the height difference limit or the total height change is reached. If the second height change (e.g., a change to the front axle) is insufficient to achieve the desired height change, i.e., if a second height change is initiated until the height difference limit is reached, a third height change can be initiated, for example, at the rear axle. This exemplary alternating axle increment approach can minimize undesirable or extreme height differences between axles. In the example, the permissible height difference between the front and rear axles can be varied depending on vehicle conditions. For example, when the vehicle is in operation or driving, the vehicle may adopt a first permissible height difference (e.g., 20 mm), which is relatively smaller than another permissible height difference (e.g., 40 mm) used during other times when the adjustment is unlikely to be noticed by the vehicle's passengers.

[0098] Turning now to Figure 10 and Figure 11 , problems can arise in air suspension systems where, for example, the air pressure of the air springs 104 on a single axle are not necessarily equal due to different circuit impedances. As shown in Figure 10 , one example approach includes opening a valve, for example, of the air spring 104 to raise or lower an axle. After determining that the axle is within a specified tolerance of a target height, the valve can be closed. In some cases, using Figure 10 the approach outlined in Figure 11 , a solution to the problem shown in Figure 10 is to subsequently, i.e., after implementing a height change using the air springs 104 associated with the opposite wheel (not shown) of the axle, equalize the pressure of the air springs 104 of a given axle. More specifically, the process 1100 can begin at block 1105 where one or more valves are opened to raise or lower an axle of the vehicle 100. Proceeding to block 1110, the valves can be closed upon detecting that the average axle height is within a target or specification. Proceeding to block 1115, with the compressor 106 closed and the exhaust valve closed, valves of the air springs 104 associated with each corner of the axle can be opened to allow the pressure in each of the air springs 104 of the axle to equalize. The process 1100 can then terminate.

[0099] Turning now to Figure 12 , an example control strategy 1200 for addressing over-correction of the air suspension system of the vehicle 100 is shown and described in further detail. More specifically, in some cases, slight dynamic maneuvers of the vehicle 100 can induce the air suspension system to make leveling corrections of the vehicle 100 that can not be necessary. In this example, a height control target of 5 millimeters (mm) is employed, i.e., such that a change of greater than 5 mm can induce a leveling response by the vehicle dynamics module 102. Slight dynamic maneuvers can induce movements that exceed the control target (e.g., 5 mm), which can induce intervention by the vehicle dynamics module 102 that is generally not desired. Attempts have been made to compensate based on acceleration of the vehicle (e.g., along the longitudinal or lateral axles of the vehicle), however, false positives can still occur, i.e., the vehicle dynamics module 102 interprets slight dynamic maneuvers as leveling corrections. To further reduce the extent to which the leveling system can attempt to correct in these mild dynamic situations, the applicable threshold for intervention can be scaled based on other factors as an alternative or in addition to scaling based on acceleration of the vehicle 100. In Figure 12In the illustrated example, the threshold for leveling intervention can be scaled based on various suspension operating conditions, such as roughness or flatness / twist.

[0100] In Figure 12 In the illustrated example control 1200, at block 1205, the suspension operating conditions can include a steering angle of the vehicle 100, a longitudinal acceleration of the vehicle 100, a lateral acceleration of the vehicle 100, a slope of a surface across which the vehicle 100 is traversing, and a grade of the surface. These factors can be used in combination with roughness and / or flatness / twist, which can be applied at block 1210 to scale the threshold. Thus, in Figure 12 In the illustrated example, each of these suspension operating conditions is used to change one or more settings associated with the suspension system. While in this example, the settings can include a threshold that is scaled as a function of roughness, flatness / twist, lateral acceleration, longitudinal acceleration, steering angle, slope, and grade, any other factors can also be relied upon as appropriate.

[0101] Generally, the suspension operating conditions can be used to provide a calibrated relationship between surface conditions (e.g., roughness and / or twist) and desensitization of height adjustments of the vehicle 100 and / or suspension system 101. Additionally, desensitization can generally be used to correct or prevent overcorrection of the vehicle height or adjustments as described above. For example, if a single one of the air springs 104 is out of range and corrected, in a four-wheel vehicle, this will necessarily cause a redistribution of vehicle load, which in turn will affect the other air springs 104. Thus, adjusting one air spring 104 of the suspension system 101 can create a need for adjustment of another air spring 104. Accordingly, the vehicle 100 can detect the occurrence of these repeated adjustments and can desensitize subsequent adjustments (e.g., to increase the acceptable tolerance / range of height adjustments) in an attempt to more quickly stop the vehicle or suspension from “seeking” subsequent adjustments.

[0102] In Figure 12 In the illustrated example control 1200, at block 1215, an adjustment count by the vehicle 100 can be used to track height adjustments of the vehicle 100. As the number of height adjustments increases over a certain period of time, the control 1200 can increase the tolerance, thereby reducing the degree to which the vehicle 100 attempts to make additional height changes. Thus, this adjustment count can be used to prevent potential “hunting” of the vehicle 100, as described above. The adjustment count can be reset or decreased upon a condition of the vehicle 100 stopping or other change indicating that the vehicle 100 should determine whether a subsequent height adjustment should be made. In this way, the threshold of the suspension system 101, such as the height adjustment threshold, can be scaled in response to the vehicle 100 detecting that too many adjustments to the vehicle height have been made over a given period of time.

[0103] At block 1220, context switching is employed to emphasize or ignore dynamic de- sensitization. More specifically, if it is known that height measurements are reliable when the vehicle 100 is in motion, it can be assumed that the height measurements remain reliable when the vehicle 100 is stopped, and thus, all de-sensitization can be applied when the vehicle 100 is stopped. On the other hand, if it is known that height measurements are unreliable when in motion, the vehicle 100 can not be able to make adjustments. Thus, in this example, when the vehicle 100 is stopped, the vehicle 100 can complete the adjustment. For example, the vehicle stop indicator of block 1215 can cause the de-sensitization to be eliminated, and the flatness to be used as the only scaling factor against the threshold.

[0104] Examples of threshold scaling as described above will now be discussed in further detail. In the subsequent examples, the height adjustment tolerance can be approximately 7.5 millimeters (mm) when in motion (i.e., when the speed of the vehicle 100 is above zero), and the height adjustment tolerance can be relatively large (e.g., 10 mm) when the vehicle 100 is stopped. Additionally, a larger tolerance can also be applied when the vehicle 100 has applied brakes (due to the close coupling of suspension components that can occur when brakes are applied).

[0105] In a first example of roughness being used to scale the height adjustment threshold, the determined amount of roughness can be used to scale a gain associated with a standard input tolerance (e.g., 10 mm when the vehicle 100 is stopped). The gain can be applied such that it changes incrementally, increasing the tolerance to a minimal degree in response to a relatively low roughness, and then increasing the tolerance rapidly when a higher roughness is detected. For example, as shown in Table 1 below, when the determined roughness is below 30%, a zero gain is applied such that the standard tolerance range of 10 mm is used. Roughness increasing to 30% can increase to a minimal degree, as reflected below, while roughness above 50% results in a large increase, effectively reducing or eliminating the height adjustment of the vehicle 100.

[0106] Table 1 - Roughness

[0107] Roughness (%) Gain 0 0 30 0.1 (e.g., 11 mm instead of 10 mm) 40 2.0 (e.g., 30 mm instead of 10 mm) 50 10.0 (e.g., 120 mm instead of 10 mm)

[0108] It should be noted that, in contrast, the maximum movement of the air spring 104 of the vehicle 100 in both the upward / downward directions can be approximately 120 millimeters - 150 millimeters. In one example, the maximum movement from the nominal position at the standard height is such that the air spring 104 can allow the wheel to bounce upward 150 mm, and the wheel to rebound downward 120 mm from the nominal position. Thus, in the example set forth in Table 1 above, the adjustment at higher levels of roughness is incrementally almost completely stopped.

[0109] The gain associated with the height adjustment threshold can be scaled in response to other factors. For example, the height adjustment threshold can be scaled using the flatness or twist as set out in Table 2 below. Again, a gain can be applied such that it changes stepwise to increase the tolerance least for relatively low levels of twist or relatively flat surfaces and then increases the tolerance rapidly upon detecting higher twist. In the example shown in Table 2 below, when it is determined that the twist is below 20mm, a zero gain is applied such that the standard tolerance range is used. An increase in twist to 30mm can increase the gain least, as reflected below, while a twist above 100mm results in a large increase, which effectively reduces or eliminates the height adjustment of the vehicle 100.

[0110] Table 2 - Twist / Flatness

[0111] Twist (mm) Gain 0 0 20 0.1 (e.g., 11 mm instead of 10 mm) 30 1.0 (e.g., 20 mm instead of 10 mm) 100 10.0 (e.g., 120 mm instead of 10 mm)

[0112] As another example of scaling the height adjustment threshold in response to a detected condition, lateral acceleration can be used to reduce or eliminate intervention of the vehicle 100 and / or suspension system 101 during relatively high lateral acceleration. An example of scaling the height adjustment threshold is set out in Table 3 below. Again, a gain can be applied such that it changes stepwise to increase the tolerance least for relatively low levels of lateral acceleration and then increases the tolerance rapidly upon detecting higher amounts of lateral acceleration. In the example shown in Table 3 below, when it is determined that the lateral acceleration is below 0.5m / s2, a zero gain is applied such that the standard tolerance range is used. An increase in lateral acceleration to 30mm can increase the gain least, as reflected below, while a lateral acceleration above 100mm results in a large increase, which effectively reduces or eliminates the height adjustment of the vehicle 100.

[0113] Table 3 - Lateral Acceleration

[0114] Lateral acceleration (m / s 2 )]]> Gain 0.5 0 3.0 3.0 (e.g., 40 mm instead of 10 mm) 10 10.0 (e.g., 120 mm instead of 10 mm)

[0115] It should be noted that in some examples, when the lateral acceleration of the vehicle 100 is above a relatively low threshold (e.g., below 3.0m / s2), the vehicle 100 can discontinue the height adjustment to prevent the vehicle from rolling out of a turn due to the lateral acceleration.

[0116] Turning now to Figures 13A to Figure 13CThe document further illustrates and describes exemplary strategies for reducing the activity of a suspension leveling system (e.g., in vehicle 100). Typically, temperature (e.g., the ambient temperature of vehicle 100 or the operating temperature of components of vehicle 100) can be detected as a suspension operating condition, and a controller (e.g., vehicle dynamics module 102) can be configured to reduce suspension activity in response to detecting a temperature above a predetermined threshold. Furthermore, in the following examples, vehicle dynamics module 102 and / or other controllers of vehicle 100 can be configured to alter suspension activity across multiple discrete suspension activity categories, where each discrete suspension activity category includes adjustments to one or more suspension operating parameters.

[0117] In Figures 13A, 13B and Figure 13C Each of the three exemplary strategies shown illustrates that certain functions of vehicle 100, particularly the air suspension, can be reduced in response to an increase in the operating temperature of the compressor or other components (e.g., due to an increase in ambient temperature), and the suspension function level can be changed in response. One exemplary suspension function level includes a “full-function” level of maintenance (e.g., where the vehicle’s air compressor (e.g., compressor 106) is allowed to fill the tank or reservoir at any time the vehicle is not stopped (if the tank is depleted) to lift the vehicle, and speed-based vehicle lifting / lowering can be implemented). The suspension function level can be reduced from the full-function level to other, more reduced suspension function or activity levels in response to detected conditions. In some examples, a reduced suspension function level may typically be used to prioritize a height change requested by the driver, prior to automatic height changes or corrections as the hardware temperature rises. Such reduction of certain functions or activities can prevent damage to components of vehicle 100 (e.g., air compressor 106) due to operation at high temperatures, or conserve power in the vehicle 100’s battery pack. (See Figures 13A, 13B, and...) Figure 13C As shown in each of the accompanying figures, after vehicle 100 or suspension components reach various temperature thresholds, vehicle 100 may limit the functionality of vehicle 100 and / or the air suspension system, as described in the “Limited Functionality” box of other examples providing suspension functionality levels. Therefore, discrete suspension functionality levels may include at least the “Limited” box, and in some examples may include additional categories discussed further below. Upon reaching the aforementioned subsequent temperature thresholds, a first additional function of the air suspension system may be limited, for example, as in… Figure 13C As described in the "Limited Functionality 2" box, the function of the air suspension system can be completely stopped. In the "No Functionality" suspension function level, the vehicle 100 may be operable, but there is no ability to modify the vehicle height or other settings of the air springs 104 and / or the suspension system.

[0118] Turning now to Figure 14 An exemplary process 1400 for a vehicle controller or system (e.g., an air suspension system or associated control system of vehicle 100) is shown. The exemplary vehicle can employ the determinations discussed above. Thus, process 1400 can be embodied on vehicle dynamics module 102 or any other appropriate controller of vehicle 100.

[0119] Process 1400 can begin at block 1405, where generally, a user height request, a user drive mode request, and a vehicle speed can be inputs to arbitrate the height request. A target height can be output.

[0120] At block 1408, process 1400 can use a measure of twist or flatness, e.g., as described above, to determine whether a height change should be denied. More specifically, based on a determination of surface conditions at block 1420, described below, process 1400 sets a flag for process 1400 (e.g., at block 1425) to allow a height change if twist of vehicle 100 is below a threshold amount. In this way, if the flag is not present at block 1425, supervisory state machine 1430 can selectively deny a height change.

[0121] Proceeding to block 1410, the target height can be used to calculate a corner height target, as well as a grade and / or slope. Thus, a height change can be made taking into account the effect of the grade and / or slope on the vehicle being traversed, e.g., as evidenced by vehicle lateral acceleration. Thus, the effect of the grade and / or slope can be removed. A target corner height can be determined and output to a corner height error calculation. Process 1400 can then proceed to block 1415.

[0122] More specifically, at block 1415, the target corner height can be input along with a measured / actual corner height for a determination of a corner height error. The corner height error can be used in a roughness calculation, e.g., for a road or any other surface, and for a calculation of a height correction.

[0123] More specifically, proceeding to block 1420, the vehicle speed can be input along with the corner height error for a determination of surface conditions, e.g., including a roughness metric, e.g., as described above in Figure 5The flatness or twist measurement of the vehicle 100, as described in the example process 500, and as described above. The roughness estimate can be an input to the calculation of the height correction at block 1425, and as described above, can be provided to block 1408 to determine whether subsequent height changes can be limited or prevented. If / when a height correction is determined at block 1425, the supervisory state machine can output a raise / lower request at block 1430 based on the input correction and the requested raise / lower received from the height request arbiter. The raise / lower request is output at block 1435 to the hardware control state machine, which outputs hardware commands to implement the raise or lower, e.g., through air pressure adjustments of the system as described herein. The process 1400 can then terminate.

[0124] In systems such as that shown in Figure 14 The body height changes can be made based on vehicle speed and / or operating mode of the vehicle / suspension system. The body height adjustments can be made based on vehicle mode and / or speed, e.g., as further shown and described in Figure 17A through Figure 17G and Figure 18 through Figure 21 Generally, various modes of the vehicle 100 can be used to emphasize energy efficiency of the vehicle (particularly in the case of the vehicle being an electric vehicle where power conservation is desired) or other desired performance / vehicle qualities. In some examples, vehicle drag can be quickly reduced by lowering the height, thereby improving the efficiency and range of the vehicle. In the illustrated examples, the body height of the vehicle can cause speed limits, e.g., such that a relatively high or relatively low body height or ground clearance can result in speed limits for the vehicle to prevent exceeding safe speeds when the vehicle has a relatively high center of gravity, as just one example. Further, the load leveling behavior can be based on the corner height in the target window. The load leveling can use the example roughness metric herein and adjust the height to remain in the target window, with additional logic added for measured height errors, and while considering that the vehicle is on different steep slopes and inclines.

[0125] In Table 1 below, a number of example body heights are shown, with corresponding ground clearances and offset distances (relative to a nominal or standard body height setting). The settings listed in Table 1 include a “highest” setting, a “high” setting, a “standard” setting, a “low” setting, and a “lowest” setting. Generally, a user of the vehicle 100 can implement the indicated ground clearance / setting under a given “mode” of the vehicle (e.g., normal mode, off-road mode, etc.), and then select one of the number of body heights. It should be appreciated that while five different body heights are shown, any number of different settings can be employed, and different ground clearances or offsets can be employed among the number of body heights.

[0126] Table 4 - Vehicle Height Offset

[0127] Vehicle Height ]]> ​ Offset from Standard (mm) ]]> ​ Highest +90 High +40 Standard Nominal (0) Low -35 Lowest -50

[0128] The ground clearance indicated in Table 1 can be the minimum ground clearance of the vehicle, measured relative to the front subframe height, and can be relatively lower than the rear subframe height of the vehicle (e.g., to provide a desired vehicle attitude with the rear of the vehicle slightly higher than the front of the vehicle).

[0129] Reference is now made to Figure 17A through Figure 17G The implementation of the vehicle body height of Table 1 is further described in different vehicle modes and in accordance with the vehicle speed of the vehicle 100. For example, different modes can be provided in the vehicle 100 to facilitate selection of different strategies for body height changes based on speed. In general, vehicle stability can be enhanced by speed limits imposed by the vehicle 100 in response to the body height. Moreover, the speed limits imposed by the vehicle 100 can be communicated to the driver upon selection of a mode or height, so that the driver has an opportunity to confirm or reconsider the height / mode request.

[0130] As noted above, the vehicle modes and sub-modes can be selected and implemented via a user interface or display, for example, as set forth above in connection with Figure 3 and Figure 4 In the subsequent examples, the vehicle 100 includes a general mode, an economy mode, a sport mode (with a "launch" sub-mode), and an "off-road" mode (with sub-modes including "auto," "rock crawl," "drift," and "rally"). As will be further described below, selection of a mode or sub-mode can result in the imposition of a vehicle height limit, for example, such that the vehicle 100 does not allow the body height to be changed above a predetermined height threshold. The various modes and sub-modes can also provide speed limits applicable to certain body heights, modes, or sub-modes, for example, selection of a relatively high body height or vehicle ground clearance above a predetermined vehicle height threshold can result in the imposition of a maximum speed limit on the vehicle and / or communication of that maximum speed limit to the operator / driver.

[0131] Figure 17A The first example shown in Table 1 involves a "general" mode in which the body height selection is limited to high / standard / low body heights, for example, as set forth in Table 1. The general mode can generally involve normal road applications or light off-road applications, and thus can use settings such as normal range body heights and other vehicle limits.

[0132] As Figure 17AAs shown in FIG. 17B, where the vehicle 100 is in the General mode, the vehicle 100 can implement automatic body height adjustments in response to changes in vehicle speed, as indicated by arrows 1700, 1702, and 1704. More specifically, when the vehicle 100 is in the "High" body height setting, the vehicle accelerating above 75 kilometers per hour (km / h) will cause the vehicle 100 to immediately lower the body height to the "Standard" body height setting, as indicated by arrow 1700. Further acceleration of the vehicle above 82 km / h will cause the vehicle 100 to lower the body height to the "Low" setting after remaining above 82 km / h for 45 seconds, as indicated by arrow 1702. Additionally, upon decelerating to 62 km / h, the vehicle 100 will automatically raise the body height back to the Standard body height, as indicated by arrow 1704. Height changes can also be prevented above 135 km / h, including automatic corrections for leveling and height changes requested by the driver / passenger of the vehicle 100. In general, the driver can be communicated changes in body height, e.g., via a display in the interior of the vehicle 100. Figure 17A through Figure 17G The various restrictions on body height changes shown in FIG. 17B can be imposed by the vehicle dynamics module 102 and / or other modules or controllers associated with the vehicle 100. In an example, the vehicle dynamics module 102 imposes restrictions related to safety, e.g., to limit vehicle body height selection to certain heights or modes, or to prevent all height changes above a vehicle speed threshold, while a separate controller or module of the vehicle 100 is responsible for imposing restrictions related to vehicle driving modes, e.g., to limit body height changes in a manner consistent with the desired user experience in each mode.

[0133] Figure 17BThe second exemplary mode shown relates to a "power-saving" mode, in which vehicle 100 typically seeks to conserve power, for example when the vehicle's traction battery has a relatively low state of charge. In power-saving mode, the vehicle height selection may be limited to standard and minimum vehicle heights, as shown in Table 1, for example. The power-saving mode can be appropriately used to reduce or minimize the power consumption of vehicle 100. In the power-saving mode of vehicle 100, the vehicle height selection is limited to between minimum and standard vehicle heights. Furthermore, vehicle 100 may perform automatic height adjustment in response to changes in vehicle speed, as indicated by arrows 1706 and 1708. More specifically, when vehicle 100 is in the standard vehicle height setting, if the vehicle accelerates above 50 km / h and remains above that speed for at least one (1) second, vehicle 100 will lower its vehicle height to the minimum vehicle height, as indicated by arrow 1706. As indicated by arrow 1708, after decelerating to 45 km / h and remaining below that speed for at least one (1) second, vehicle 100 will automatically raise its vehicle height back to the standard vehicle height. At speeds above relatively high levels, such as above 135 km / h, changes in altitude are also prevented. Figure 17B As shown. Energy-saving modes typically aim to reduce power consumption by minimizing wind resistance at higher speeds and reducing the number of lift / lower events by decreasing the number of vehicle height settings.

[0134] Figure 17C The third exemplary mode shown relates to a "sport" mode, in which the vehicle can be relatively lowered, suspension components are set to a relatively rigid configuration, etc. Therefore, in sport mode, the vehicle height selection can typically be limited to a lower vehicle height to reduce the vehicle's center of gravity height. For example, as... Figure 17C The sport mode shown restricts the vehicle 100's ride height to the low and minimum ride heights listed in Table 1. Furthermore, automatic ride height adjustment is disabled (i.e., it must be manually entered or requested by the vehicle driver to change between low and minimum ride heights), and ride height adjustment is completely locked above 135 km / h.

[0135] Turn now Figure 17D The exemplary fourth mode involves a "motion-initiated" mode / sub-mode. More specifically, it can be... Figure 3 The "Start" sub-mode can be initiated from the menu of the user interface shown in Figure 4. In Start sub-mode, vehicle settings such as the vehicle height can be set to the lowest / most rigid available settings to further lower the vehicle's center of gravity, which may be useful, for example, for accelerating from a standing stop to maximum acceleration. Figure 17D As shown, in Sport Start mode, vehicle 100 remains at the lowest vehicle height setting, and all other vehicle heights are unavailable.

[0136] Figure 17E The fifth exemplary mode shown relates to an "Auto Off-Road / Rock Crawling" mode, which may be appropriate when the vehicle 100 traverses wilderness or obstacles at a relatively low speed. For example, when the vehicle 100 is in "Off-Road" mode, an "Auto" or "Rock Crawling" sub-mode can be selected, for example, as described above. Figure 3 and Figure 4 As described. Available vehicle heights are limited to high and maximum vehicle height. The automatic driving height setting is locked. When the vehicle is at its maximum vehicle height, the vehicle speed is limited to 40 km / h. At speeds above 20 km / h, additional requests from the driver to raise the vehicle height from high to maximum are locked. Furthermore, at speeds above 135 km / h, vehicle height adjustment is completely locked.

[0137] Figure 17F The sixth exemplary mode shown relates to the "Off-road Drift" and "Off-road Rally" modes / sub-modes of vehicle 100. For example, when the vehicle is in "Off-road" mode, the "Drift" and "Rally" sub-modes can be selected. In the Off-road Drift and Off-road Rally modes / sub-modes, the vehicle height selection can be limited to standard and high vehicle heights, as shown in Table 1, for example. Furthermore, automatic vehicle height adjustment is disabled, and vehicle height adjustment is completely locked above 135 km / h.

[0138] Figure 17G The seventh exemplary mode shown relates to the "trailer towing mode" of vehicle 100. When the vehicle is moving (i.e., above 0 km / h), all vehicle height adjustments are disabled, and manual vehicle height adjustment options are limited to standard and low vehicle height.

[0139] Now for reference Figure 18 The process 1800 for setting a vehicle speed limit in response to a suspension system height input is shown and described in further detail. Process 1800 may begin at block 1805, where the vehicle speed limit is applied and communicated. For example, when the vehicle is raised to a relatively high or maximum vehicle height (e.g., body height) relative to the ground, it may be desirable to limit the speed of vehicle 100 so that higher speeds cannot be achieved. Figure 17A through Figure 17G The exemplary vehicle modes shown herein implement the vehicle heights specified in Table 1, with the maximum vehicle height only available in Off-Road Auto / Rock Crawling modes. Furthermore, as described above... Figure 17EAfter selecting the highest body height within the off-road automatic / rock crawl mode, the vehicle speed can be limited to 40 km / h. One or more of the body heights can be above a predetermined vehicle height threshold applicable to the speed limit, such that when the vehicle 100 is at a body height above the limit, the speed limit can be imposed and / or communicated to the operator / driver. Other maximum speeds can be employed as appropriate and can be applicable to other body / ground heights of the vehicle. As noted above, in some examples, the driver can be communicated the speed limit imposed by the vehicle 100, e.g., in response to the body height selection, such that the driver has an opportunity to confirm or reconsider the height / mode request.

[0140] Proceeding to block 1810 of the process 1800, initially the speed limit of the vehicle 100 can be maintained, e.g., in response to confirming that the body height selection that resulted in the imposition of the speed limit (e.g., selection of the highest body height) has changed in response to the limit being communicated at block 1805 (e.g., the driver changes their mind). Initially, at block 1810, the speed limit is maintained until the vehicle 100 confirms that the height achieved is less than the height selection that resulted in the imposition of the speed limit. Thus, so long as the highest body height is requested, the vehicle 100 can monitor the body height selection and maintain the speed limit until it is confirmed that the vehicle has not achieved the highest body height. In response to detecting that the vehicle achieved body height is less than the highest body height (e.g., in response to a driver input), the vehicle 100 can remove the speed limit imposed at block 1815.

[0141] Turning now to Figure 19 and Figure 20 An example process for providing an "easy entry" function in a vehicle (e.g., the vehicle 100) is shown and described in further detail. The vehicle 100 can have an easy entry feature or mode that can be disabled by default in the vehicle 100, but can be selected by a user / driver. Generally, the easy entry function can facilitate a lowering of the vehicle to enhance the ease of entry into the vehicle by a vehicle occupant. Figure 19An example process 1900 is shown in more detail. Upon detecting that the vehicle 100 is parked, the process 1900 proceeds to block 1905. Generally, at block 1905, the process 1900 can change the vehicle body height setting to the lowest available vehicle body height. In the illustrated example, block 1905 includes a first block 1905a and a second block 1905b. At block 1905a, a target minimum height is set for the vehicle 100. In examples, at block 1905a, the vehicle 100 can begin lowering to the target minimum height, e.g., the lowest vehicle body height as set forth in Table 1. Proceeding to block 1905b, upon detecting that a vehicle door is opened, the process 1900 can raise the target height to the next highest vehicle body height in real-time. For example, if the vehicle is between the "minimum" and "low" vehicle body heights when lowering, upon determining that a door is opened, the vehicle 100 can raise to the "low" vehicle body height (rather than continuing to lower to the "low" height). Thus, in the sense that the vehicle 100 has not reached the minimum vehicle body height setting when the door is opened, the process 1900 generally avoids the door contacting an obstacle (which would have otherwise been possible if the vehicle 100 continued to lower when the door was opened). The process 1900 can then terminate. Turning now to Figure 20 Another example process 2000 associated with the easy entry feature of the vehicle 100 is shown and described in more detail. Generally, in the process 2000, a previously selected target height can be implemented in response to determining that the vehicle 100 is not parked or otherwise ready to travel. Thus, the vehicle 100 can be raised from a lowered position to a desired vehicle body height (e.g., a height in which the vehicle 100 was previously moved) to facilitate egress from the vehicle 100. In the illustrated example, at block 2005, the target is set to the previously selected height in response to the vehicle 100 being displaced from a parked position. The vehicle 100 can continue to raise until the target vehicle body height is reached, or it can otherwise no longer be necessary to continue raising the vehicle 100 (e.g., the vehicle mode or selected vehicle body height is lowered, the vehicle loses power, etc.). The process 2000 can then terminate.

[0142] Referring now to Figure 21 An example process 2100 implementing load leveling behavior of the vehicle 100 is shown and described in further detail. In the example process 2100, roughness can generally influence changes in the vehicle body height of the vehicle 100. More specifically, in the illustrated example, an assessment of the surface (e.g., road surface, ground, track, etc.) being traversed by the vehicle can be used to determine whether to implement a vehicle height change.

[0143] The process 2100 can begin at block 2105, where a standby state can be used when the vehicle 100 or components thereof monitor the target corner height of the vehicle 100. For example, as the vehicle 100 moves along a given surface, the process 2100 can monitor one or more corner heights of the vehicle 100, e.g., to determine whether the corner height is within an applicable range. When the vehicle 100 detects that the corner height is not within the target window, the process 2100 can proceed to block 2110.

[0144] At block 2110, the process 2100 can evaluate the ground, e.g., road, track, or other surface being traversed by the vehicle 100. For example, the process 2100 can determine a roughness, e.g., as described above in Figure 5 block 2100. Block 2110 can classify the result as above or below a threshold to determine whether the surface being traversed is “smooth” or “rough.” In the case where the roughness is determined to be “smooth” at block 2110, the process 2100 can proceed to block 2115.

[0145] At block 2115, the process 2100 can initiate an adjustment to the corner height that was initially determined to be outside of the applicable target window.

[0146] Alternatively, in the case where the roughness is determined to be rough at block 2110, the process 2100 can proceed to block 2105 to standby. In this way, the process 2100 can prevent the vehicle 100 from attempting to level when traversing a relatively rough surface (or the vehicle is on a non-horizontal surface, etc., as described above with respect to Figure 5

[0147] It should be noted that the process 2100 can proceed from block 2105 to block 2115 in response to detecting that the height target has changed, e.g., the vehicle 100 has initiated an automatic change in the ride height, or a driver / user of the vehicle 100 has manually requested a change in the ride height. Accordingly, the process 2100 can proceed to adjust the corner height of the vehicle 100. Upon confirming that the corner heights of the vehicle are each within their applicable target window, the process 2100 can proceed to block 2105.

[0148] Turning now to Figure 22 , an example process 2200 for implementing a change in height of a vehicle, e.g., the vehicle 100, is shown and described in further detail. Generally, the process 2200 can facilitate a change in ride height based on different control parameters. The use of different control parameters can be particularly beneficial in the context of vehicles having air suspension systems, such as the vehicle 100, although they can also be used in the context of other suspension systems.

[0149] ​Generally, under nominal operating conditions, the vehicle 100 and / or suspension system 101 can close a control loop around a target movement of the suspension (e.g., displacement of one or more air springs 104). However, at other times, controlling the vehicle ride height based on the target movement or displacement can be difficult. For example, if the vehicle 100 is positioned on an uneven surface, rocks, etc., such that one wheel is relatively unloaded or "hanging" off the ground, adding / removing air to / from the air spring 104 of the unloaded wheel can not cause a detectable displacement of the air spring 104. Thus, the vehicle 100 can be unable to determine whether the air spring 104 has been properly adjusted based on the displacement / position of the air spring 104, and it can be difficult to use displacement / position as a control parameter to control the vehicle ride height change at such times.

[0150] In view of such shortcomings of displacement / movement based control, the example process 2200 and / or vehicle 100 can control suspension adjustments based on different parameters when the displacement control criteria are not met (e.g., displacement control is not feasible or can be ineffective). In other words, the displacement control criteria can be defined to determine that displacement / position can be used as a control parameter.

[0151] When the process 2200 determines that displacement / position can be ineffective under the displacement control criteria, the vehicle 100 can control the addition / removal of air relative to the air spring 104 based on a different control parameter than displacement or position. For example, the process 2200 can use air mass rather than displacement as a control parameter. In this example, the vehicle 100 can determine a target air mass for one or more (and in some examples, all) of the air springs 104 based on the ride height change request. The vehicle 100 can determine the target air mass based on a measurement of the temperature of the air springs 104, reservoirs, or other suspension components. The vehicle 100 can also determine the target air mass based on a measured displacement of the air springs 104. Based on the known air mass in the air springs 104, the vehicle 100 can then add / remove an amount of air to / from the air springs 104 to achieve the target air mass of the air springs 104. Because the air mass associated with the air springs 104 can be more easily measured or detected than displacement / position when, for example, the wheels of the air springs 104 are unloaded or substantially unloaded, the control loop based on air mass can more effectively implement the change in ride height change than a control loop based on displacement / position. Thus, even under conditions where an adjustment to the air springs 104 can not cause a measurable movement of the air springs 104 displacement (e.g., due to the suspension of the wheel being fully extended or relatively unloaded), a proper adjustment can still be made to achieve the ride height change.

[0152] The process 2200 can begin at block 2205, where a height change request for a vehicle suspension is received. The process 2200 can then proceed to block 2210.

[0153] At block 2210, a height control method for implementing the height change can be selected in response to the height change request. In some examples, multiple height controls can be used. One example height control is displacement control, where air is added to or removed from one or more air springs of a vehicle suspension based on a target displacement of the one or more air springs. Another example height control is air mass control, where air is added to or removed from the one or more air springs of a vehicle suspension based on a target air mass change of the one or more air springs.

[0154] As noted above, air mass control can be advantageous in certain conditions, such as when displacement control can be ineffective. In examples, the vehicle 100 and / or the process 2200 can select different controls, such as displacement control or air mass control, based on conditions. More specifically, the vehicle 100 can consider conditions that can indicate a likelihood that displacement control is effective to implement a height change request. As noted above, displacement control can be ineffective when one or more wheels / air springs 104 are relatively unloaded, such as when the wheels are “suspended” from the vehicle due to uneven surfaces, rocks, etc.

[0155] The vehicle 100 and / or the process 2200 can consider various factors that can indicate conditions in which displacement control can be ineffective or otherwise can face challenges. In at least some examples, the vehicle 100 can consider a displacement of one or more of the springs of the vehicle 100 when selecting a control for implementing a height change. As will be explained in further detail below, the displacement can be used to determine whether a spring (e.g., an air spring 104) of the suspension is unlikely to be controlled using a displacement / position of the spring as a control parameter for body height changes. The displacement of the air spring 104 can be used to evaluate a displacement control criterion, and a control parameter / variable for implementing body height changes can be selected based on the displacement control criterion. In subsequent examples, various displacement control criteria can be defined to evaluate conditions to determine whether displacement can be used as a control parameter for implementing body height changes.

[0156] In one example, the displacement of a spring (e.g., air spring 104) can be evaluated to determine whether a displacement control criterion is satisfied, enabling the use of displacement as a control parameter. Generally, the displacement of a relatively unloaded air spring 104 can be substantially different compared to at least one other air spring 104 of the vehicle 100 when a wheel or air spring 104 of the vehicle 100 is relatively unloaded. For example, the vehicle 100 can be positioned on an uneven surface such that three wheels (and associated air springs 104) support the load of the vehicle 100, with the fourth wheel hanging in the air such that the air spring 104 is extended longer compared to the other air springs 104, or even fully extended. In this case, the displacement of the air spring 104 of the hanging wheel will be substantially greater than the displacement of the other three air springs 104. Similarly, the displacement of a single one of the air springs 104 can also be indicative of a relative displacement with respect to the other air springs 104 of the vehicle, which can indicate that displacement control can not be feasible, and / or that air mass control would be beneficial. For example, if one of the air springs 104 is at maximum displacement (i.e., the wheel is fully extended from the vehicle), this can generally indicate that the other air springs 104 of the vehicle are not fully extended. In other words, this can also indicate that the associated air spring 104 is relatively unloaded when the vehicle is stationary or at a relatively low speed, in the sense that one wheel of the vehicle is fully or substantially fully extended. Thus, the other wheels / air springs 104 of the vehicle must carry a greater proportion of the vehicle load and are relatively less extended. Accordingly, in some examples, a displacement control criterion indicative of a selection of air mass control can be determined from the displacement of a single one of the wheels or air springs 104. For example, the displacement of one or more of the air springs 104 can be compared to a displacement threshold (e.g., based on a maximum or minimum displacement or other appropriate threshold) to determine whether the displacement control criterion is satisfied.

[0157] A displacement control criterion indicative of air mass control potentially being beneficial can also be indicated by the level of twist of the vehicle. As described above, twist can be defined as the difference between the relative displacement difference of one wheel of the vehicle 100 compared to a different axle. If the comparison of the displacements of the air springs 104 results in a twist level above a twist threshold, this can also indicate that at least one wheel / air spring 104 is relatively unloaded, and thus air mass control for vehicle height change can be beneficial.

[0158] In another example, the displacement control criteria indicative of air mass control can be beneficial can be determined as a function of the load of one or more of the air springs 104. The air springs 104 can include load sensors that directly measure the load of the air springs 104. Alternatively, the vehicle dynamics module 102 or other controller of the vehicle 100 can be configured to determine the load based on the measured displacement of the air springs 104 and any other measurements (e.g., vehicle load, pitch / roll, air mass, and / or temperature). In an example, if the air springs 104 are below a load threshold (e.g., a minimum load) or are unloaded, this will also be indicative of the air springs 104 being fully extended or substantially fully extended and the other air springs 104 / wheels of the vehicle 100 bearing a relatively large share of the vehicle load (and thus being relatively less extended).

[0159] In another example, multiple of the foregoing factors (i.e., load, displacement, and twist) are considered collectively or any appropriate subset in determining the displacement control criteria.

[0160] It should also be noted that, in the sense that displacement control can not be feasible or can not be effective, this can also be indicative that an independent / separate control approach for the air springs 104 of the vehicle can also be beneficial relative to the average axle height approach. As noted above, under some operating conditions of the vehicle 100, it can be desirable to control the height / changes of the vehicle 100 based on an average of the measurements between two air springs 104 of the vehicle 100. However, as noted above, in situations where one wheel of an axle is relatively unloaded or relatively displaced compared to the other wheels of the same axle, a separate or independent axle height control approach (i.e., where the control objective is implemented independently at each air spring 104 of a single axle of the vehicle 100) can be desirable. Thus, in at least some example approaches, the selection of air mass control at block 2210 also results in the selection of independent axle height control.

[0161] The process 2200 can then proceed to block 2215. At block 2215, adjustments to one or more springs of the vehicle 100 can be initiated based on the control selected at block 2210. In the case of displacement control being selected at block 2210, a target displacement or position of one or more of the air springs 104 of the vehicle 100 can be set and adjustments can be made to the air springs 104 (e.g., by adding / subtracting air from the air springs 104) in an attempt to achieve the target displacement.

[0162] On the other hand, where air quality control has been selected at block 2210, at block 2215, an air quality target can be set. The vehicle 100 (e.g., the vehicle dynamics module 102) can identify a target air quality based on measurements associated with the suspension system 101. The vehicle dynamics module 102 can determine a target air quality change, i.e., an amount of air to add or subtract from one or more air springs 104. The vehicle dynamics module 102 can also determine an action to implement the target air quality change based on one or more of a displacement of the air spring or a temperature of the air reservoir or suspension components. Thus, by way of example only, the vehicle 100 can set a target air quality based on a temperature of a suspension component (e.g., the air spring 104) (e.g., in the sense that temperature affects expansion / contraction of air within the air spring 104) or position.

[0163] After the adjustment of block 2215 is complete, the process 2200 can proceed to block 2220. At block 2220, the process 2200 can query whether the control target setting of block 2215 has been achieved. In examples, the determined control target (e.g., a displacement target or an air quality target) is compared to actual measurements. In the event the process 2200 determines that the target has been achieved, or that the actual measurements are within a predetermined acceptable range, the process 2200 can terminate. Alternatively, if the target has not been achieved, the process 2200 can return to block 2210, where the process 2200 can again determine an appropriate control parameter and proceed to adjust a component of the air suspension 101 of the vehicle 100. In the sense that a first type of control parameter (e.g., displacement) is selected and determined to be ineffective, the process 2200 can select a different control parameter (e.g., air quality) in a subsequent attempt.

[0164] The systems and processes discussed above are intended to be illustrative and not restrictive. Those skilled in the art will appreciate that the actions of the processes discussed herein can be omitted, modified, combined, and / or rearranged, and that any additional actions can be performed without departing from the scope of the disclosure. More generally, the disclosure above is intended to be exemplary, not limiting. Therefore, the scope of the claimed application should be determined by the claims and not by the disclosure above. Additionally, it should be noted that features and limitations described in connection with any one embodiment can be applied to any other embodiment, and that the flow diagrams or examples can be combined, reordered, or performed in parallel with any other embodiment. Furthermore, the systems and methods described herein can be performed in real-time. It should also be noted that the systems and / or methods described above can be applied to or used in accordance with other systems and / or methods.

[0165] While some portions of the disclosure can refer to "conventions" or examples, any such reference is merely to provide context of the disclosure and is not to be construed as an admission that any of the conventional aspects constitute prior art.

[0166] The above description includes exemplary embodiments according to the present disclosure. These examples are provided only for the purpose of illustration and are not intended to limit the present disclosure in any way. It will be appreciated that those having ordinary skill in the art will be able to devise various modifications, optimizations and alternative constructions without departing from the intended scope of the following claims.

Claims

1. A suspension system for a vehicle, the suspension system comprising: a controller configured to: determine a change in roughness of a ground surface associated with the vehicle; modify a height adjustment tolerance for the suspension system in response to the determined change in roughness; facilitate modification of the suspension system based on the determined height adjustment tolerance; determine a twist of the suspension system based on a difference between a first lateral displacement difference of a front axle of the vehicle and a second lateral displacement difference of a rear axle of the vehicle; and determine a subsequent height adjustment tolerance for the suspension system based on at least the determined twist.

2. The suspension system of claim 1, wherein the controller is configured to determine the roughness by determining a roughness metric based on a change in corner height error over a time period corresponding to the ground surface traversed during the time period.

3. The suspension system of claim 2, wherein the corner height error is a difference between an expected vehicle body height and an actual vehicle body height.

4. The suspension system of claim 1, wherein the controller is configured to determine the roughness by determining a ground input magnitude based on a change in corner height error over a time period corresponding to the ground surface traversed during the time period.

5. The suspension system of claim 1, wherein the controller is configured to determine the roughness by determining a moving average of a change in corner height error over a time period.

6. The suspension system of claim 1, further comprising one or more air springs, wherein the controller is configured to change an amount of air contained by the one or more air springs to change a corresponding vehicle corner height.

7. The suspension system of claim 1, further comprising: an air reservoir having a compressed air storage volume; and a valve block assembly controlled by the controller, the valve block assembly configured to direct a flow of air from the air storage volume to one or more air springs of the suspension system.

8. An air suspension system for a vehicle, the air suspension system comprising: one or more air springs; a controller configured to: determine a change in roughness of a ground surface associated with the vehicle; modify a height adjustment tolerance for the suspension system in response to the determined change in the roughness, wherein height adjustment is achieved by changing an amount of air contained by the one or more air springs; facilitate modification of the suspension system based on the determined height adjustment tolerance; determine a twist of the suspension system based on a difference between a first lateral displacement difference of a front axle of the vehicle and a second lateral displacement difference of a rear axle of the vehicle; and determine a subsequent height adjustment tolerance for the suspension system based on at least the determined twist.

9. A method for controlling a suspension system of a vehicle, the method comprising: determining, using a controller, a change in roughness of a ground surface associated with the vehicle, the roughness determined based on a vehicle body height; ​ ​ ​ modifying, using the controller, a height adjustment tolerance of a suspension system of the vehicle based on the determined change in roughness; facilitating modification of the suspension system based on the determined height adjustment tolerance; determining a twist of the suspension system based on a difference between a first lateral displacement difference of a front axle of the vehicle and a second lateral displacement difference of a rear axle of the vehicle; and determining a subsequent height adjustment tolerance of the suspension system based on at least the determined twist.

10. The method of claim 9, wherein determining the roughness comprises determining a change in corner height over a time period corresponding to the ground traversed during the time period.

11. The method of claim 10, wherein determining the roughness comprises determining a change in corner height error over the time period.

12. The method of claim 11, wherein determining the roughness comprises determining a moving average of the corner height error over the time period.

13. The method of claim 11, wherein the corner height error is a difference between an expected vehicle body height and an actual vehicle body height.

14. The method of claim 9, further comprising increasing a height adjustment tolerance in response to an increase in roughness of the ground.

15. The method of claim 9, further comprising decreasing a height adjustment tolerance in response to a decrease in the roughness of the ground.

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