Method and device for dealing with discontinuity of road surface

Abstract

To provide a suspension system that at least partially protects an occupant from disturbance induced by a road and decreases the impact of acceleration involving running in a lateral direction, a longitudinal direction, a vertical direction, and the like.SOLUTION: At least partially based on information about a pothole on a road, a controller can be used for selecting one of at least two strategies for traversing the pothole on the road with wheels of a first suspension assembly. The first strategy can include traversing a majority of the length of the pothole on the road while the wheels of the first suspension assembly are hanging in the air (i.e., not in contact with or substantially not in contact with the bottom of the pothole on the road). The second strategy can include traversing a majority of the length of the pothole on the road while the wheels of the first suspension assembly are in contact with or substantially in contact with the bottom of the pothole on the road, for example, by rolling along the bottom of the pothole on the road.SELECTED DRAWING: Figure 17

Description

[Technical Field]

[0001] The disclosed embodiments mitigate the effects of potholes and other road surface discontinuities. This invention relates to a suspension system including a damper and a suspension actuator, and the control thereof, for achieving this. [Background technology]

[0002] A vehicle's suspension system protects it from road-induced disturbances. It is intended to at least partially protect the occupants and reduce the effects of accelerations associated with travel, such as lateral, longitudinal, and vertical. One type of unpleasant event that is often encountered during vehicle travel occurs when one or more wheels of the vehicle traverse a pothole or depression or pit in the road surface. This can be an unpleasant experience for the vehicle occupants. Not only this, but it can also cause significant damage to the vehicle's suspension, wheels, and tires. Summary of the Invention

[0003] Some embodiments of an active suspension actuator of a suspension assembly of a vehicle can collect information about a pothole. The pothole can have a base and a length along the direction of travel of the vehicle. Based at least in part on the information about the pothole, a controller can be used to select one of at least two strategies for traversing the pothole with the wheels of the first suspension assembly. The first strategy can include traversing a majority of the length of the pothole while the wheels of the first suspension assembly are airborne (i.e., not in contact with or substantially not in contact with the base of the pothole). The second strategy can include traversing a majority of the length of the pothole while the wheels of the first suspension assembly are in contact with or substantially in contact with the base of the pothole, for example, by rolling along the base of the pothole. In some embodiments, the selected strategy can be implemented by activating a damping element of the first suspension assembly. In some embodiments, the collected information can include, for example, a vehicle speed or a vehicle sprung mass. In some embodiments, the information about the pothole may include the relative position of the pothole with respect to the vehicle. The collected information, in some embodiments, may include data from a map, GPS data, terrain-based positioning data, and / or data from a sensor associated with a first wheel preceding a second wheel of the vehicle.

[0004] In some embodiments where the selected strategy is the first strategy described above, a protruding discrepancy distance between the wheel and the road surface at the end of the pothole can be determined. In some embodiments, a predetermined compressive force can be applied to the wheel assembly by a suspension actuator of the first suspension assembly to reduce the expected discrepancy at the end of the pothole. In some embodiments, actuators of the second and / or third suspension assemblies can be used to adjust, e.g., increase, the ride height of the vehicle while the wheel of the first suspension assembly is airborne and traversing the pothole. can.

[0005] In some embodiments, a compressive force can be applied by an actuator of a fourth suspension assembly during at least the period when the wheel associated with the first suspension assembly is airborne. The fourth suspension assembly is located at a corner of the vehicle diagonally opposite the corner at which the first suspension assembly is located. In some embodiments, a locking mechanism is used to lock the actuator of the first suspension assembly. This prevents extension of the actuator at least during the time that the wheel of the first suspension assembly is in the air.

[0006] In some embodiments of the active suspension system of the vehicle, a discontinuity in the road surface can be detected. A spring element operationally interposed between the sprung mass of the vehicle and a wheel of a first suspension assembly of the active suspension system. The discontinuity can be traversed by the wheels of the first suspension assembly by controlling the suspension actuators of the first suspension assembly with a controller to apply a compressive force to the spring elements operatively interposed between the sprung mass of the vehicle and the wheels of the first suspension assembly. The wheels associated with the first suspension assembly can be airborne during at least a portion of the time period during which the discontinuity is traversed and / or the wheels of the first suspension assembly are airborne. In some embodiments, during the time period during which the wheels of at least the first suspension assembly are airborne, the suspension actuators of at least the second suspension assembly can be controlled to apply a tension force to spring elements operatively interposed between the sprung mass of the vehicle and the wheels associated with the second suspension assembly, thereby increasing the load applied to the corresponding wheels, and thereby increasing ground clearance for the vehicle in some embodiments. In some embodiments, during the time period during which the wheels of at least the first suspension assembly are airborne, the suspension actuators of the third suspension assembly can be controlled to apply a compressive force to spring elements operatively interposed between the sprung mass of the vehicle and the wheels of the third suspension assembly, thereby reducing the load applied to the corresponding wheels. In some operating situations, the discontinuity can be a pothole. In some embodiments, the second suspension assembly may be located at a corner of the vehicle that is opposite the first suspension assembly in the fore / aft and / or lateral direction of the vehicle, and correspondingly, the third suspension assembly may be located at a corner of the vehicle that is diagonally opposite the corner at which the first suspension assembly is located.

[0007] In some embodiments, a vehicle suspension system includes a first suspension assembly. The first suspension assembly can include a spring element operably interposed between a sprung mass of the vehicle and a wheel assembly, and a damping element operably interposed between the sprung mass of the vehicle and the wheel assembly in parallel with the spring element. The damping element can include a hydraulic cylinder having a piston connected to a piston rod, the piston dividing the hydraulic cylinder into a compression volume and an extension volume, and a valve assembly configured to prevent fluid flow from the extension volume in a first mode of operation (e.g., during extension) and allow fluid flow to the extension volume in a second mode of operation (e.g., during compression). The compression volume can be a volume adjacent a side of the piston that is compressed when the damping element is compressed, and the extension volume can be a volume adjacent a second side of the piston opposite the first that is compressed when the damping element is extended. In some embodiments, the valve assembly can be configured to allow fluid flow into and out of the extension volume during certain modes of operation. In some embodiments, the valve assembly can include at least one valve that is electrically controlled. In some embodiments, the valve assembly can also include at least one valve that is a passive valve. In some embodiments, the damping element can be an active suspension actuator having two fluid flow paths. A first fluid flow path can pass through a hydraulic pump / motor, and a second fluid flow path does not pass through the hydraulic pump / motor. Flow in the second fluid flow path can be controlled by one or more valves, which can include an electrically controlled valve.

[0008] In another embodiment, a method for controlling an active suspension actuator of a suspension assembly of a vehicle includes collecting information about a pothole having a base and a length along a direction of vehicle travel, and based at least in part on the information about the pothole: The method includes selecting one of at least two strategies for traversing the pothole with the wheels of the first suspension assembly, the first strategy including traversing a majority of the length while the wheels of the first suspension assembly are airborne and the second strategy including traversing more than half of the length while the wheels of the first suspension assembly are in contact with the bottom of the pothole; activating a damping element of the first suspension assembly of the vehicle; and implementing the selected strategy.

[0009] In yet another embodiment, a method of controlling an active suspension system of a vehicle includes detecting a discontinuity in a road surface; traversing the discontinuity with a wheel of a first suspension assembly of the active suspension system; controlling a suspension actuator of the first suspension assembly with a controller to apply a compressive force to a spring element operatively interposed between a sprung mass of the vehicle and the wheel of the first suspension assembly; and maintaining the wheel of the first suspension assembly airborne while at least a portion of the wheel traverses the discontinuity.

[0010] In yet another embodiment, a vehicle suspension system includes a first suspension assembly. The first suspension assembly may include a spring element operably interposed between a sprung mass of the vehicle and a wheel assembly, and a damping element operably interposed between the sprung mass of the vehicle and the wheel assembly in parallel with the spring element. The damping element may include a hydraulic cylinder having a piston connected to a piston rod, the piston dividing the hydraulic cylinder into a compression volume and an extension volume, and a valve assembly configured to prevent fluid flow from the extension volume in a first mode of operation and to allow fluid flow to the extension volume in a second mode of operation.

[0011] In another embodiment, a method of controlling an active suspension system of a vehicle having four wheels associated with four corners of the vehicle includes applying a first force having a first magnitude to at least partially support the first corner of the vehicle with a first suspension assembly; applying a second force having a second magnitude to at least partially support a second corner of the vehicle adjacent the first corner with the first suspension assembly; obtaining information that the first wheel associated with the first corner has become airborne or is about to become airborne while traversing a pothole; and increasing the magnitude of the second force with an active suspension actuator associated with the second corner based at least in part on the information.

[0012] In yet another embodiment, a method for controlling an active suspension system of a vehicle includes determining that a first wheel of the vehicle is about to traverse a road discontinuity and increasing ground clearance of the vehicle based at least in part on the determination that the first wheel is about to traverse the road discontinuity.

[0013] In yet another embodiment, a method for controlling an active suspension system of a vehicle includes determining that a first wheel of the vehicle is about to traverse a road discontinuity, and at least partially inhibiting movement of the first wheel into the road discontinuity, for example, by using an active suspension actuator, while at least the first wheel is traversing the road discontinuity.

[0014] In another embodiment, a method for controlling an active suspension system of a vehicle includes determining that a first wheel of the vehicle is about to traverse a road discontinuity, and reducing a load applied to a second wheel at a corner of the vehicle diagonally opposite the corner of the vehicle at which the first wheel is located while the first wheel is traversing the road discontinuity.

[0015] It will be appreciated that the foregoing concepts, and additional concepts discussed below, may be arranged in any suitable combination, and that the disclosure is not limited in this respect. Furthermore, it will be understood that the disclosure is not limited to the exact configurations, variations, structures, features, embodiments, aspects, methods, advantages, improvements, and instrumentalities shown and / or described. Furthermore, the various configurations, variations, structures, features, embodiments, aspects, methods, and instrumentalities may be used alone in a system or method, or in combination with other configurations, variations, structures, features, embodiments, aspects, methods, and instrumentalities. Furthermore, other advantages and novel features of the present disclosure will become apparent from the following detailed description of various non-limiting embodiments, when considered in conjunction with the accompanying drawings. [Brief explanation of the drawings]

[0016] [Figure 1] 1 shows a vehicle having four suspension assemblies. [Figure 2] 2 shows the left front suspension assembly of FIG. 1. [Figure 3] 3 shows an exploded view of the suspension assembly of FIG. 2. [Figure 4] 3 shows a partially exploded view of the suspension assembly of FIG. 2. [Figure 5] 1 shows a top view of a vehicle approaching a pothole. [Figure 6] 3 shows the suspension assembly of FIG. 2 with no force applied to the spring element. [Figure 7] 3 shows the suspension assembly of FIG. 2 with only static forces applied to the spring elements. [Figure 8] 3 shows the suspension assembly of FIG. 2 with the spring element extended due to dynamic and / or extension forces applied by the active suspension actuator. [Figure 9] 3 shows the suspension assembly of FIG. 2 with the spring element compressed by dynamic and / or compressive forces applied by the active suspension actuator. [Figure 10] Shows four tracks of a vehicle wheel suspended in the air while crossing a pothole. [Figure 11] 1 shows the vehicle wheel positions for three different pothole end elevations. [Figure 12] 1 shows pothole penetration distance versus vehicle longitudinal travel for various compression force levels generated by the active suspension actuators. [Figure 13] 1 shows the interaction of a wheel that remains airborne while crossing a pothole with the pothole edge wall. [Figure 14] Shows a wheeled vehicle entering a pothole and running along the bottom of the pothole. [Figure 15] The wheel of FIG. 14 is shown running along the bottom of a pothole and then impacting the end wall. [Figure 16] 1 shows a hydraulic active suspension system having a hydraulic lock to prevent actuator extension and a passive one-way bypass of the hydraulic lock. [Figure 17] FIG. 1 illustrates an example block diagram of a damping element control system. DETAILED DESCRIPTION OF THE INVENTION

[0017] The adverse effects of traversing a road surface discontinuity, such as a pothole or other depression, may depend, for example, on the length and / or depth of the discontinuity, the vehicle's speed, the weight of the sprung and / or unsprung mass, the weight distribution of the sprung mass, and the configuration of the vehicle's suspension system. The inventors have recognized that a properly designed, configured, and operated active suspension system can ameliorate these and other adverse effects. As used herein, unless the context indicates otherwise, the term pothole refers to a road surface discontinuity that affects a single vehicle. means a pothole of such size and / or position relative to the vehicle that the wheel enters the pothole while the rest of the vehicle remains on the road surface.

[0018] Typically, the weight of the sprung mass, i.e., the total vehicle body weight (TVW), which includes, for example, the weight of the vehicle body, the occupants in the vehicle, and any cargo, is affected by the road surface. It is supported by multiple vertical forces or force components applied to one or more wheels / tires on each side and transmitted to the body by the vehicle suspension system.

[0019] FIG. 1 shows a vehicle 1 at rest or traveling at a constant speed (i.e., zero acceleration) on a horizontal road surface (not shown). In situations where the vehicle is not undergoing acceleration, the vehicle's suspension may be subjected to static forces due to TVW. In the embodiment of FIG. 1, vehicle 1 includes a body 2 and four suspension assemblies 3a-3d. The weight of body 2 and its contents (not shown) contributes to a road reaction force 4a (F1 applied to the left front tire) The vehicle is supported by road reaction force 4a (F2 applied to the right front tire), road reaction force 4b (F2 applied to the right front tire), road reaction force 4c (F3 applied to the left rear tire), and road reaction force 4d (F4 applied to the right rear tire). For a non-accelerating vehicle, the sum of these forces F1, F2, F3, and F4 may be equal to TVW. Although road reaction forces 4a-4d in FIG. 1 are represented by vertical arrows of equal length, this does not necessarily indicate that the four forces are of equal magnitude in all embodiments and / or under all conditions. In some embodiments, all vertical forces when the vehicle is not accelerating may be equal, approximately equal to each other (i.e., all forces are within ±10% of the average of these forces), or significantly different from each other (i.e., at least one of the depicted forces is greater than ±10% of the average of all forces). Note that because the road also supports the weight of each unsprung mass, for example, only a portion of the total force applied by the road surface at each wheel may be transmitted to the vehicle body.

[0020] In some embodiments, the average value of these forces (F) over an extended period of time, such as an hour, a day, or more, is used. 1ave , F 2ave , F 3ave , and F 4ave) may be constant, and the sum of the average quantities may equal TVW. However, momentarily, particularly during dynamic operation of the vehicle, in some embodiments, these forces may fluctuate depending on the vehicle dynamics. For example, when a vehicle rolls due to making a right turn, forces F1 and F3 may increase. In such a situation, this increase may be a function of the vehicle's speed and the radius of the turn. As a result, forces F2 and F4 may decrease in magnitude. Additionally, additional transverse or lateral forces may be applied to the tires or wheels. In some embodiments, when a vehicle is braking, forces F1 and F2 may initially increase and F3 and F4 may decrease as the vehicle leans forward. In some embodiments, when a vehicle traverses a valley between two hills, each of forces F1-F4 may reach a peak when the corresponding wheel reverses its vertical direction of travel and then return to its average value.

[0021] In the embodiment of FIG. 1, forces F1-F4 are transmitted to the vehicle body 2 by suspension assemblies 3a-3d, which are operatively interposed between the vehicle body 2 and wheel assemblies 5a-5d, respectively. In some embodiments, each of the suspension assemblies may include spring elements (e.g., without limitation, coil springs, leaf springs, air springs, and / or any other suitable springs) and damping elements (e.g., without limitation, passive dampers, semi-active dampers, and / or active suspension actuators). Damping elements that are active actuators may alternatively be referred to herein as active suspension actuators. Active suspension actuators are actuators operatively interposed between a sprung mass (e.g., the vehicle body) and an unsprung mass (e.g., the wheel assemblies) and can apply active forces (i.e., forces in the direction of motion) and passive or resistive forces (i.e., forces opposite to the direction of motion).

[0022] In some embodiments, each suspension assembly may include a spring element operatively interposed between the vehicle body and the wheel in a parallel orientation to the damping element. In some embodiments, the suspension assembly may also include an upper mount or other mounting device (not shown) interposed between the damping element and the vehicle body and visible in line with the damping element.

[0023] FIG. 2 shows a suspension assembly 3a of the suspension system of FIG. The suspension assembly 3a includes a spring element 10a and a damping element 11a. In this embodiment, the spring element and the damping element are arranged in a parallel orientation. Both the spring element 10a and the damping element 11a are interposed between the vehicle body (i.e., sprung mass, not shown) and the wheel assembly (i.e., unsprung mass) 5a. The spring element and the damping element may be connected to the vehicle body directly or by one or more interposed devices 15a. The interposed devices may be, for example, upper mounts and / or upper spring loads. The cornering force 16a (F) exerted by the vehicle body on the suspension assembly 3a is 1corner ) represents the net force supported by the suspension assembly 3a. F 1corner may include a portion of the TVW plus the dynamic force applied to the right front suspension assembly. In the embodiment of FIG. 2, the force F applied to the intervention device 15a 1corner is resisted by forces exerted by the damping element and / or spring element. In a static state, the force exerted by the damping element (neither compressed nor extended) may be zero under certain conditions, but may also be large. In some embodiments, the force exerted by the damping element may exceed the force exerted by the spring element, for example, if the damping element is an active suspension actuator.

[0024] In some embodiments, if the damping element is a passive or semi-active damper, even in a static state (i.e., when the damping element is not undergoing compression or extension), the damping element may exert an extension force equal to, for example, the precharge pressure multiplied by the cross-sectional area of ​​the piston rod 16a. This force exerted by the damping element due to the precharge pressure is hereinafter referred to as the precharge force of the damping element. In some embodiments, mechanical, electrical, and / or hydraulic locking mechanisms may be included (described below) and used to lock the wheel assembly in place relative to the vehicle body during compression and / or extension.

[0025] When the damping element of a suspension assembly is an active suspension actuator, the damping element may apply a compressive or an extensible force within the performance characteristic limits of the actuator. This force may be an active force (i.e., a force in the direction of motion) or a passive force (i.e., a force resisting motion). The force applied by the damping element may be equal to, greater than, or less than the force applied by the spring element at a given position of the wheel assembly relative to the vehicle body. The active force applied by an active suspension actuator during compression is referred to herein as an active compression force. The active force applied by an active suspension actuator during extension is referred to herein as an active extension force.

[0026] 3 shows an exploded view of the suspension assembly 3a in a static state (i.e., when the vehicle acceleration is zero). The corner force 16a is the force acting on the corner weight W corner (i.e., the portion of the TVW supported by suspension assembly 3a). Also, since other suspension assemblies support equal or nearly equal corner weights, the sum of all corner weights may be equal to the TVW.

[0027] W corner is a damper force of 20a F D and spring force 20b F SAt the same time, the damping element 11a and the spring element 10a exert forces 21a and 21b on the wheel assembly, which are equal in magnitude to 20a and 20b, respectively. road ) is equal to and resists the sum of forces 21a and 21b plus the weight of the unsprung mass. In this situation, the spring element is compressed by force 20b (which is equal to 21b), resulting in a compressed length 19 (L) of the spring element. C ) occurs. L C can be calculated from Equation 1.

[0028]

number

[0029] where K is the spring constant of the spring element 10a, and L F is the unstressed (or free) length of the spring element, which is discussed below. In the art, Equation 1 is sometimes referred to as Hooke's Law.

[0030] The equilibrium static forces shown in Figure 3 can be disturbed, for example, by acceleration of the vehicle and / or wheel assembly in one or more directions. The equilibrium can also be disturbed if wheel 23a becomes airborne, for example, while crossing a pothole.

[0031] If wheel 23a becomes airborne, the forces acting on wheel assembly 5a will no longer be balanced and the wheel assembly may begin to accelerate according to Equation 2.

[0032]

number

[0033] where ΣF is the net force (i.e., the sum of the unbalanced forces) acting on the wheel assembly. M US is the mass of the unsprung mass, and a US is the acceleration of the unsprung mass.

[0034] 4 shows the state of the suspension assembly 3a when there is no or substantially no force exerted by the ground, for example because the wheel 23a is airborne. In this embodiment, when the wheel 23a is airborne, for example, the unsprung mass (M US There can be three forces acting on the spring element F: S 41b, (2) Damping element force F D 41a, and (3) the weight of the wheel assembly W WA 41c. If these forces are not balanced, the wheel assembly shown in the embodiment of Figure 4 may begin to accelerate relative to the vehicle body (not shown).

[0035] If the damping element is a passive or semi-active damper, the force F exerted by the damping element on the wheel assembly 5a D may initially (i.e., when the wheel assembly becomes airborne) be directed away from the vehicle body (i.e., downward) due to precharge pressure. As the velocity of the wheel assembly increases in a downward direction under the influence of the net force acting on the wheel assembly, the force exerted by the damping element may reverse direction and become a force resisting this motion. This resisting force may be proportional to the product of the damping coefficient of the damping element and the velocity of the wheel assembly relative to the vehicle body. If the damping element shown in FIG. 4 is an active actuator, the force F D may be, for example, a resistive force, an active compression force, or an active extension force, which may be applied, for example, from the moment the wheels 23 a become airborne, later than that point, or even before the wheels become airborne, as commanded by one or more controllers of the active suspension actuators.

[0036] In the embodiment of Figure 4, the magnitude and / or timing of the force applied by the actuator may be commanded by the controller based on a prediction of the position of the wheel 23a relative to the pothole at a given speed of the vehicle. This prediction may be determined, at least in part, based on information from various sensors, such as, for example, forward-looking sensors such as LiDAR, radar, acoustic transducers, and / or cameras. Alternatively or additionally, The prediction may be based, at least in part, on a localization algorithm and / or map data, for example from a digital remote map or a local (i.e., stored on the vehicle) map, GPS, terrain-based localization data, data collected by the vehicle's leading wheel assembly and used by a controller controlling, for example, the suspension actuators of the last wheel assembly, etc.

[0037] When the vehicle is supported, for example, on a road or other surface, the spring element 10a may be used alone or The damping element exerts a precharge force that can be compressed sufficiently to support the cornering weight of the vehicle. As soon as the vehicle is airborne, the spring element exerts a force F S and the weight of the wheel assembly 5a may cause the wheel assembly to accelerate downward. At the same time, the damper element may apply a retarding force to the wheel assembly. The damper force F D The wheel alignment to the vehicle body The damping coefficient may be a function of the product of the assembly velocity and the damping coefficient of the damper element. In the case of a passive damper, the damping coefficient may be a constant, while in the case of a semi-active damper, the damping coefficient may be a variable within an operating range determined by a controller. If the damping element is an active suspension actuator, it may be used to apply a force to the wheel assembly 5a that can at least partially or completely counter the force applied by the spring element at a given position of the wheel assembly relative to the vehicle body. If the actuator has sufficient force capacity, the suspension actuator may be used to hold the wheel assembly in position relative to the vehicle body or to move it closer to the vehicle body (i.e., compress the suspension assembly). Alternatively, if the damping element applies a force less than the spring force, the wheel assembly may accelerate away from the vehicle body with an acceleration proportional to the unbalance force, but this acceleration may be less than if there was no force applied by the damping element.

[0038] Figure 5 shows the L P5 shows a top view of vehicle 1 approaching a meter-long pothole 41. The vehicle may have four wheels: left front wheel 23a, right front wheel 23b, right rear wheel 23c, and left rear wheel 23d. Axis 45a connects the center of the contact surface of the right front wheel to the center of the contact surface of the diagonally opposite left rear wheel. Axis 45b connects the center of the contact surface of the left front wheel to the center of the contact surface of the diagonally opposite right rear wheel. Intersection point 44 is the intersection of axes 45a and 45b, and point 43 is a top view of the center of gravity of vehicle 1. In the embodiment of FIG. 5, center of gravity 43 is located forward of intersection point 44. However, in some embodiments, the center of gravity may be at other locations relative to point 44 as determined by the mass distribution of the vehicle, the occupants, and the load the vehicle is carrying, and the disclosure is not so limited. In this illustration, wheel 23a may enter pothole 41 while wheels 23b, 23c, and 23d are on the road surface. Alternatively, wheel 23d may enter pothole 41 while wheels 23b, 23c, and 23a are on the road surface. In some cases, the left front wheel 23a and the left rear wheel may enter the pothole in succession as the vehicle passes over it.

[0039] In the embodiment shown in FIG. 5, if wheel 23a becomes airborne while traversing pothole 41, the road reaction forces on all four tires may be affected. For example, an airborne wheel 23a does not contact the road and therefore has no road reaction force, which may result in an unbalanced net force on its associated wheel assembly. In some embodiments, under these circumstances, the reaction to the TVW acting on center of gravity 43 may be supported by one or more of the other three wheels. The vehicle's TVW acting on center of gravity 43 may induce a moment about axle 45a equal to the vehicle weight multiplied by moment arm 43a.

[0040] Additionally, when wheel 23a (shown in FIG. 1) becomes airborne and spring element 10a is at least partially unstressed, the force exerted by the compressed spring element 10d of the diagonally opposed suspension assembly may exert an unbalanced moment about axis 45a. This unbalanced moment may be in the same direction as the moment induced by the TVW acting on the center of gravity. Accordingly, in some embodiments, a compression force may be exerted on suspension assembly 3d (shown in FIG. 1) using, for example, a suspension actuator, at the time wheel 23a becomes airborne, before wheel 23a becomes airborne, and / or after wheel 23a becomes airborne to reduce or counteract the effect of the force exerted by spring element 10d. For example, the compression force exerted by the suspension actuator may oppose the extension force exerted by its associated spring, which may result in the spring and suspension element of suspension assembly 3d being compressed. The net load on the wheel is reduced by the total force applied to the wheel by the motion actuators. In some embodiments, the wheel at the opposite corner may be partially unloaded or completely unloaded. In either case, by reducing the force applied to the wheel assembly at the corner diametrically opposite the corner where the wheel is traversing the pothole, the unbalanced moment on the vehicle is reduced, which can reduce the movement of the wheel into the pothole as it traverses the pothole.

[0041] As noted above, in some embodiments of the vehicle shown in FIG. 1, if wheel 23a becomes airborne, the diagonally opposing wheel may also become unloaded. This results in an increase in the portion of the TVW supported by suspension assembly 3b and / or suspension assembly 3c, which in some embodiments may be substantially the entire TVW. Under these circumstances, one or more suspension actuators, which may be included in suspension assemblies 3b and 3c, may be used to maintain the vehicle's ground clearance by increasing the magnitude of the extension force between the corresponding wheel assembly and the vehicle body (sprung mass) that accommodates the portion of the TVW that is unloaded from the other suspension assemblies. Alternatively, such suspension actuators may be used to increase or decrease the ground clearance depending on the magnitude of the extension force applied by the suspension actuators of those suspension assemblies.

[0042] Figures 6 to 9 show various degrees of extension and compression of the suspension assembly of Figure 2. In Figure 6, no force is applied to the spring element by the rest of the assembly (shown as a ghost image). Under these conditions, the spring element has a free length L F 50. In FIG. 7, the suspension assembly is shown in the presence of only static forces (i.e., no acceleration), and the spring element has a static length L S In this state, the precharge force applied by the spring element 10a and the damper element 11a supports the weight of the left front corner of the vehicle. S can be calculated using Equation 3.

[0043]

number

[0044] where K is the spring constant of the spring element 10a. Figures 8 and 9 show the spring element in tension and compression, respectively. The spring element can be extended by applying a tension force to it, or compressed by applying a compression force to it. Such forces can be the result of dynamic forces acting on the vehicle body and / or can result from forces applied by active suspension actuators.

[0045] FIG. 10 illustrates an operating situation in which wheel 23a of suspension assembly 3a becomes airborne (i.e., becomes unsupported by the road surface, ground, or any other surface), for example, while traversing a pothole or other discontinuity in road surface 61a. As discussed above, once the wheel becomes airborne, it may descend into the pothole, following a path, e.g., 63a, 63b, 63c, 63d, etc. As discussed above, the path followed may depend, for example, on the net force acting on the wheel assembly (including its weight) and the mass of the wheel assembly. Additionally, the extent to which the wheel descends into the pothole may depend on the vehicle's speed and the length of the discontinuity along the direction of travel, which may determine the length of time the wheel remains airborne. Alternatively, the extent to which the wheel penetrates into the pothole may be limited or eliminated by a locking mechanism, such as the locking system described below.

[0046] In the embodiment shown in Figure 10, the pothole start elevation 61a is illustrated as being equal to the pothole end elevation 61b of the road surface. However, as shown in Figure 11, The pothole end height may be higher (level 61c) or lower (level 61d) than the pothole start height 61a. As shown in FIG. 11 , the discrepancy distances (shown as ghost images) 69b, 69c, and 69d between the wheel 23a contact patch positions at the end of the pothole may be at least partially a function of the pothole end heights 61b, 61c, and 61d. Also, as shown in FIG. 11 , the pothole may have a bottom 65 that is lower than both the pothole start height and the pothole end height. The pothole may also have a proximal wall 64 and an end wall 63 (see FIG. 10 ).

[0047] The suspension system embodiment of FIG. 10 traversing a pothole can operate under the example, non-limiting conditions detailed in Table I below.

[0048] [Table 1]

[0049] where MOI is the moment of inertia of the sprung mass about axis 45a shown in FIG.

[0050] Figure 12 shows the trajectory from the point where wheel 23a of Figure 10 becomes airborne as a function of the compression force applied by damping element 11a. Table II shows the compression force for each trajectory of Figure 11.

[0051] [Table 2]

[0052] For the exemplary embodiment and operating conditions shown in FIG. 10 and Table I, as shown in FIG. In , four tracks experience significant pothole penetration.

[0053] Figure 13 illustrates a situation in which a wheel travels far enough into a pothole that it strikes the pothole's end wall. Strikes against the end wall, which can result in damage to the wheel, tire, and / or one or more suspension components, for example. In the diagram of Figure 12, distance 70 ("X") represents how far the wheel falls below the top of the end wall (or pothole exit elevation). Distance X may be equal to the amount of extension of the spring element plus the extent to which the corner of the vehicle falls toward the pothole due to the unbalanced moment on the vehicle when the wheel becomes airborne.

[0054] In the embodiment shown in Figure 13, if wheel 23a becomes airborne while traversing a pothole, the upward force on the left front corner of the vehicle body may be reduced. Note that this force may not immediately decrease to zero because, for example, the spring element may exert an unbalanced force that causes the wheel assembly to accelerate downward. The spring may consequently exert an equal and opposite force on the vehicle body.

[0055] Under some operating conditions, the vehicle may rotate about axis 55a in Figure 5 as a result of the weight of the vehicle acting substantially on the center of gravity 53 and / or the spring element 11c applying an unbalanced force. Note that if the wheel 23a is prevented from accelerating, or if the magnitude of the acceleration is reduced by applying a compressive force by the active suspension actuator, the rotation about axis 55a may become large.

[0056] In Figure 13, a corner of the vehicle may fall into the pothole, resulting in the mounting device 5a dropping an amount Y71. At the same time, the spring element may expand an amount Z, such that X = Y + Z. As discussed above, the distance X depends in part on the length of time the wheel is airborne, which may depend, for example, on the length "d" of the pothole, and the speed of the vehicle. The mass of the wheel assembly and the forces exerted by the spring and damper elements may also affect the distance X. Note that the longer the pothole (length d) and the slower the vehicle's speed, the further the wheel may fall into the pothole and the more severe the impact with the pothole's edge wall may be.

[0057] Thus, in some embodiments and under certain circumstances, it may be preferable to apply an extension force via the active suspension actuators, for example, before, after, or at the time the wheel begins to cross the pothole. Figure 14 illustrates an operating situation in which the active suspension actuators are used to apply an extension force to extend the suspension assembly so that the wheel 23a can ride along the bottom of the pothole without becoming airborne. When operated in this manner, the suspension assembly can maintain vehicle height 90 despite the presence of the pothole. As shown in Figure 15, the wheel 23a may strike the edge wall of the pothole 41.

[0058] FIG. 16 illustrates one embodiment of an active suspension actuator 99a. A housing 100a includes a piston 101a, a piston rod 16a, a fluid-filled compression volume 102a, and a fluid-filled extension volume 103a. The hydraulic circuit of FIG. 16 includes a pressurized fluid reservoir 104a in fluid communication with the compression volume and a fluid reservoir 105a in fluid communication with the extension volume. In some embodiments, these reservoirs are at least partially filled, for example, with air or another compressible medium. One port of a bidirectional hydraulic pump / motor 106a is in fluid communication with the compression volume 102a and a second port is in fluid communication with the extension volume 103a. In some embodiments, the bidirectional hydraulic pump / motor may be a hydraulic motor capable of operating as a hydraulic pump or a hydraulic pump capable of operating as a hydraulic motor.

[0059] In some embodiments, a valve assembly 107a can be used to control fluid flow from and / or to the extension volume. In some embodiments, the valve assembly can include a two-position control valve 108a. In a first position, the valve 108a allows free or substantially free bidirectional fluid flow to and from the extension volume, and in a second position, hydraulically locks the extension volume to prevent fluid from exiting the extension volume and causing the active suspension actuator to undergo extension. In some embodiments, a check valve 109a is used to allow unrestricted or substantially unrestricted flow in one direction into the extension volume. The check valve 109a can be configured to prevent cavitation in the extension volume in the event of rapid compression of the suspension actuator. Such rapid compression can occur, for example, when a wheel comes into contact with the road surface after becoming airborne while crossing a pothole.

[0060] In some embodiments, a bypass control system 110a can be used to enable fluid exchange between the expansion and compression volumes that bypasses the hydraulic pump / motor, such that fluid flows between the expansion and compression volumes without passing through the hydraulic pump / motor. The bypass control system can include one or more valves, which can include one or more control valves. The hydraulic pump / motor can be used to actively control the movement of the piston 101a. A flow restrictor 111a can be interposed between the reservoir 105a and the hydraulic circuit. The restrictor can act as a low-pass filter to restrict fluid flow into or out of the reservoir at high frequencies.

[0061] While specific embodiments of suspension actuators are described above in connection with Figure 16, it will be understood that the present disclosure is not limited to implementation with only the illustrated actuators. Accordingly, the disclosure is not so limited, and any suitable actuator capable of providing the desired functionality described herein may be used.

[0062] FIG. 17 shows a block diagram of one embodiment of an exemplary control system 120 for controlling one or more damping elements 121 of a suspension assembly of a vehicle (not shown). The damping elements can be, for example, semi-active dampers or active suspension actuators. The controller 122 can receive information from one or more sources, including, for example, (i) a network 123, such as a wireless network; (ii) a GPS receiver 124; (iii) a localization algorithm 125; (iv) a lead wheel assembly sensor 126; (v) an electronic data storage device, such as computer memory or a disk drive; and (vi) one or more preview sensors 128 (e.g., lidar, radar, ultrasonic transducer, video camera) and one or more vehicle sensors 128a that measure one or more vehicle state parameters. The controller can also exchange information with one or more secondary controllers 129 within the vehicle. The controller can use data from one or more sources to determine, for example, the location of a pothole relative to the vehicle, the size of the pothole, the depth of the pothole, and the vehicle's speed. The controller can also gather information regarding the possibility of avoiding the pothole. The controller can then determine a strategy for crossing.

[0063] In some embodiments, based on the collected information, the controller can adjust the operation of one or more damping elements. For example, based on the collected information, the controller can select to traverse the pothole while the wheels are airborne or by driving into the pothole and driving along the bottom of the pothole. The controller 122 can adjust the damping coefficients of one or more semi-active damping elements or suspension actuators of various suspension subassemblies. Alternatively or additionally, the controller can select to activate one or more hydraulic locking mechanisms.

[0064] For example, a car may be traveling too slowly or the pothole may be too large, causing the car to crash while in the air. If it is determined that the hole cannot be traversed, the controller may activate the active suspension actuators to extend the wheels, allowing them to travel along the bottom of the hole. Additionally, the controller may increase the compression force when the wheels reach the edge wall of the hole to facilitate the wheels' withdrawal from the hole.

[0065] Alternatively or additionally, the controller can communicate, directly or with at least one other controller, to modify the operation of at least one other suspension assembly. For example, a controller controlling the operation of a left front wheel of a vehicle can identify a pothole and determine its relative position, size, and wheel speed. The controller can further select to traverse the pothole while the wheel is airborne. The controller can determine that the left front wheel is likely to strike the pothole end wall with a certain misalignment. Furthermore, the controller can communicate, directly or with at least one additional controller, to operate the at least one additional controller to reduce the protrusion misalignment between the left front wheel and the pothole end elevation by raising at least a portion of the vehicle. For example, the controller can raise the right front and left rear of the vehicle by an amount equal to or greater than the misalignment amount. Additionally or alternatively, the controller can cause an actuator controller of a right rear suspension assembly to apply a compressive force to a spring element or fix the right rear wheel in a proper position relative to the vehicle body while the right front wheel is airborne. It should be noted that the vehicle may be an autonomous vehicle or a driven vehicle.

[0066] In some embodiments, a vehicle may include a suspension assembly associated with each of four corners, such as the vehicle shown in FIG. 1 . Each suspension assembly may support a portion of the TVW by applying a net force to the vehicle. Each suspension assembly may include an active suspension actuator that can be used to modify the net force applied by the respective suspension assembly. In such embodiments, based at least in part on determining that a first wheel of the vehicle, such as wheel 5a, has become airborne or is about to become airborne while traversing a pothole, a controller may be used to alter operation of the active suspension actuators in one or more of the other suspension assemblies to change the net force applied by one or more of those other suspension assemblies. This may be, for example, to at least partially compensate for the loss of support from the first wheel that has become airborne. For example, in FIG. 1 , the net actuator force applied by suspension assembly 3b and / or suspension assembly 3c, located at the corner adjacent to the first corner, may be increased. In some embodiments, the force applied by suspension assemblies 3c and / or 3d may be increased before or after first wheel 23a becomes airborne.

[0067] Additionally or alternatively, based at least in part on determining that the first wheel is airborne, the controller may modify operation of an active suspension actuator of a first suspension assembly associated with the first corner (e.g., 3a). The associated actuator may be used to, for example, apply a compressive force to an associated spring element (e.g., 1a) to reduce or eliminate penetration of the first wheel into a pothole. Further, in some embodiments, an actuator of a suspension assembly at an opposite corner to the first corner may be used to apply a compressive force to an associated spring element to reduce or eliminate a rolling moment induced by a spring element associated with a spring assembly at a fourth corner (e.g., spring element 3d).

[0068] In the above-described embodiments, a controller may be understood to refer to one or more processors operatively coupled with associated memory, which may be a non-transitory computer-readable medium. The memory may include computer-readable instructions that, when executed by the one or more processors, may perform any of the disclosed methods in any suitable manner. The suspension systems, sensors, and other components described herein are operated to perform in combination.

[0069] While the present teachings have been described in connection with various embodiments and examples, it is not intended that the present teachings be limited to such embodiments or examples. Rather, the present teachings encompass various alternatives, modifications, and equivalents, as will be appreciated by those skilled in the art. Accordingly, the foregoing description and drawings are by way of example only.

Claims

1. 1. A method of controlling an active suspension actuator of a suspension assembly of a vehicle, comprising: collecting information about a pothole having a bottom and a length along a direction of travel of the vehicle; selecting one of at least two strategies for traversing the pothole with a wheel of a first suspension assembly based at least in part on the information about the pothole, a first strategy including traversing a majority of the length while the wheel of the first suspension assembly is airborne, and a second strategy including traversing more than half of the length while the wheel of the first suspension assembly is in contact with a bottom of the pothole; activating a damping element of the first suspension assembly of the vehicle; and implementing the selected strategy.

2. The method of claim 1 , further comprising: collecting information about the vehicle; and selecting the strategy is also based on the information about the vehicle.

3. The method of claim 2 , wherein the information about the vehicle is selected from the group consisting of a speed of the vehicle and a mass distribution of a sprung mass of the vehicle.

4. The method of claim 3 , wherein the information about the pothole includes a position of the vehicle relative to the pothole.

5. 5. The method of claim 4, further comprising collecting, by the controller, information about the pothole, the information selected from the group consisting of map data, GPS data, terrain-based location data, and data from wheels other than the first wheel.

6. The method of claim 1 , wherein the selected strategy is the first strategy.

7. The method of claim 6 , further comprising estimating a protrusion mismatch distance when the first wheel is at the end of the pothole.

8. 8. The method of claim 7, further comprising applying a predetermined compressive force by the actuator of the first suspension assembly at least during the period when the wheel of the first suspension assembly is airborne.

9. 8. The method of claim 7, further comprising increasing ground clearance of the vehicle by using an actuator of a second suspension assembly while the wheel of the first suspension assembly is traversing the pothole.

10. 9. The method of claim 8, further comprising increasing ground clearance of the vehicle by using an actuator of a second suspension assembly while the wheel of the first suspension assembly is traversing the pothole.

11. 11. The method of claim 10, further comprising increasing the ground clearance of the vehicle by using an actuator of a third suspension assembly during the period when the wheel of the first suspension assembly is traversing the pothole.

12. at least the period during which the wheel of the first suspension assembly is airborne 12. The method of claim 11, further comprising: applying a predetermined compressive force by the actuator of a fourth suspension assembly, the fourth suspension assembly being at a corner of the vehicle diagonally opposite the corner at which the first suspension assembly is located.

13. 7. The method of claim 6, further comprising immobilizing the actuator of the first suspension assembly to prevent extension of the actuator at least during periods when the wheel of the first suspension assembly is airborne.

14. 1. A method for controlling an active suspension system of a vehicle, comprising: Detecting discontinuities in the road surface; traversing the discontinuity with a wheel of a first suspension assembly of the active suspension system; controlling a suspension actuator of the first suspension assembly to apply a compressive force to a spring element operatively interposed between a sprung mass of the vehicle and the wheel of the first suspension assembly; and maintaining the wheel of the first suspension assembly suspended in the air while at least a portion of the wheel traverses the discontinuity.

15. 15. The method of claim 14, further comprising controlling with a controller a suspension actuator of at least the second suspension assembly to apply an extension force to a spring element operatively interposed between the sprung mass of the vehicle and a wheel of a second suspension assembly during at least a period when the wheel of the first suspension assembly is airborne.

16. 16. The method of claim 15, further comprising controlling with a controller a suspension actuator of the third suspension assembly to apply a compressive force to a spring element operatively interposed between the sprung mass of the vehicle and a wheel of a third suspension assembly, at least during the period that the wheel of the first suspension assembly is airborne.

17. The method of claim 16 , wherein the discontinuity is a pothole.

18. A suspension system for a vehicle, comprising: a first suspension assembly, a spring element operatively interposed between the sprung mass of the vehicle and the wheel assembly; a damping element operatively interposed between the sprung mass of the vehicle and the wheel assembly in parallel with the spring element, a hydraulic cylinder having a piston connected to a piston rod, the piston dividing the hydraulic cylinder into a compression volume and an extension volume; a valve assembly configured to prevent fluid flow from the extension volume in a first mode of operation and to allow fluid flow to the extension volume in the first mode of operation; and a damping element including a first suspension assembly.

19. 20. The suspension system of claim 18, wherein the valve assembly is further configured to allow fluid flow into and out of the extension volume during a second mode of operation.

20. 10. The valve assembly of claim 1, wherein the valve assembly includes at least one electrically controlled valve.

10. The suspension system according to claim 9.

21. 21. The suspension system of claim 20, wherein the valve assembly also includes at least one valve that is a passive valve.

22. 22. The suspension system of claim 21, wherein the damping element is an active suspension actuator including a first fluid flow path connecting the compression volume and the expansion volume, and a second fluid flow path connecting the compression volume and the expansion volume.

23. 23. The suspension system of claim 22, wherein the first fluid flow path passes through a hydraulic pump / motor and the second fluid flow path bypasses the hydraulic pump / motor.

24. 24. The suspension system of claim 23, wherein flow in the second fluid flow path is controlled by an electrically controlled valve.

25. 1. A method of controlling an active suspension system of a vehicle having four wheels associated with four corners of the vehicle, comprising: a) using a first suspension assembly; applying a first force having a first magnitude to at least partially support a first corner of the vehicle; applying a second force having a second magnitude to at least partially support a second corner of the vehicle adjacent the first corner; b) obtaining information that a first wheel associated with the first corner has become airborne or is about to become airborne while traversing a pothole; c) increasing the magnitude of the second force using an active suspension actuator associated with the second corner based at least in part on the information.

26. applying a third force having a third magnitude to at least partially support a third corner of the vehicle adjacent the first corner; increasing the magnitude of the third force using an active suspension actuator associated with the third corner based at least in part on the information; and 26. The method of claim 25, further comprising:

27. 27. The method of claim 25 or 26, further comprising applying a compressive force using an active suspension actuator associated with the first corner based at least in part on the information.

28. 1. A method for controlling an active suspension system of a vehicle, comprising: determining that a first wheel of the vehicle is about to traverse a road discontinuity; increasing a ground clearance of the vehicle based at least in part on determining that the first wheel is about to traverse the road discontinuity; and A method comprising:

29. 29. The method of claim 28, wherein the discontinuity is a pothole.

30. 30. The method of claim 28, further comprising at least partially restraining the first wheel from moving into the road discontinuity while at least the first wheel is traversing the road discontinuity.

31. 30. The method of claim 28, further comprising reducing a load applied to a second wheel at a corner of the vehicle that is diagonally opposite the corner of the vehicle at which the first wheel is located.

32. 30. The method of claim 28, further comprising increasing the load applied to third and fourth wheels located longitudinally and laterally relative to the first corner.

33. 1. A method for controlling an active suspension system of a vehicle, comprising: determining that a first wheel of the vehicle is about to traverse a road discontinuity; at least partially restraining the first wheel from moving into the road discontinuity while at least the first wheel is traversing the road discontinuity; and at least partially restraining movement of the first wheel includes applying a compressive force, by an active suspension actuator, to a spring element operatively interposed between a sprung mass of the vehicle and the first wheel.

34. 34. The method of claim 33, further comprising increasing ground clearance of the vehicle based at least in part on determining that the first wheel is about to traverse the road discontinuity.

35. 34. The method of claim 33, further comprising reducing a load applied to a second wheel at a corner of the vehicle that is diagonally opposite the corner of the vehicle at which the first wheel is located.

36. 1. A method for controlling an active suspension system of a vehicle, comprising: determining that a first wheel of the vehicle is about to traverse a road discontinuity; reducing a load applied to a second wheel at a corner of the vehicle diagonally opposite the corner of the vehicle at which the first wheel is located while the first wheel is traversing the road discontinuity; and A method comprising:

37. 37. The method of claim 36, wherein the discontinuity is a pothole.

38. 37. The method of claim 36, further comprising increasing ground clearance of the vehicle based at least in part on determining that the first wheel is about to traverse the road discontinuity.

39. 37. The method of claim 36, further comprising at least partially restraining movement of the first wheel into the road discontinuity while at least the first wheel is traversing the road discontinuity.

40. 40. The method of claim 39, wherein at least partially restraining movement of the first wheel comprises applying a compressive force to a spring element operatively interposed between the vehicle sprung mass and the first wheel.

41. 40. The method of claim 39, wherein at least partially restraining movement of the first wheel comprises fixing movement of the first wheel.

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