Active suspension control for repetitive surface undulations

Abstract

A control system (300) configured to control an active suspension system (104) of a vehicle (100), the control system comprising one or more controllers (301), wherein the control system is configured to: determine (702) that the vehicle is traveling on or approaching a repetitive surface undulation; determine (709) the vehicle speed; determine (708) an indication of the surface wavelength of the repetitive surface undulation; and control (722, 728) the active suspension system based on the vehicle speed and the surface wavelength to control at least one of the guide wheel suspension frequency and the trailing wheel suspension frequency.

Description

Technical Field

[0001] This disclosure relates to active suspension control for repetitive surface undulations. In particular, but not exclusively, this disclosure relates to the control of a vehicle's active suspension system based on repetitive surface undulations. Background Technology

[0002] Due to repeated vehicle traffic, roads and lanes made of loose or deformable materials can evolve into undulations over time. On frequently traveled roads, these undulations resemble a sine wave pattern. Undulations can also occur on other types of roads.

[0003] For comfort, the driver will choose a speed that results in minimal body turbulence. This speed depends on the surface wavelength of the undulating surface and the inherent passive frequency of the vehicle's suspension. If the driver chooses a speed that is too fast or too slow, the vehicle's suspension may enter a resonant frequency, resulting in excessive body pitch and / or wheel bounce. This causes discomfort to the vehicle occupants and may lead to contact between the front of the vehicle and the next undulation.

[0004] The undulations referred to in this article are those with wavelengths longer than the wheelbase of a typical vehicle. Summary of the Invention

[0005] The purpose of this invention is to give drivers more options regarding their speed when driving on undulating roads while maintaining vehicle stability.

[0006] According to one aspect of the invention, a control system configured to control an active suspension system of a vehicle is provided, the control system comprising one or more controllers, wherein the control system is configured to: determine that the vehicle is traveling on or approaching a repeating surface undulation; determine the vehicle speed; determine an indication of the surface wavelength of the repeating surface undulation; and control the active suspension system based on the vehicle speed and the surface wavelength to control at least one of the guide wheel suspension frequency and the trailing wheel suspension frequency.

[0007] In some examples, the indication of the surface wavelength depends on information from at least one of the following sensors: an accelerometer; a set of suspension displacement sensors; a wave crest detection system; a communication interface configured for vehicle-to-vehicle and / or infrastructure-to-vehicle communication; or a position sensor, wherein the control system is configured to retrieve historical data using position data from the position sensor.

[0008] In some examples, the control system is configured to determine a surface frequency, wherein the surface frequency is proportional to the vehicle speed divided by the surface wavelength, and wherein the control of the active suspension system is based on the surface frequency.

[0009] In some examples, the control system is configured to disable control of the active suspension system if the surface frequency drops below a lower threshold associated with the surface frequency.

[0010] In some examples, the control system is configured to disable control of the active suspension system if the surface frequency exceeds an upper threshold associated with the surface frequency.

[0011] In some examples, the control system is configured to determine the target suspension frequency of the trailing wheel and / or the target suspension frequency of the guide wheel based on the surface frequency.

[0012] In some examples, the control system is configured to control at least one of the following: controlling the target suspension frequency of the trailing wheel to be greater than the surface frequency; and controlling the target suspension frequency of the guide wheel to be less than the surface frequency.

[0013] In some examples, the control system is configured to increase the trailing wheel target suspension frequency relative to the surface frequency, wherein the amount of increase in the trailing wheel target suspension frequency is inversely proportional to the vehicle speed.

[0014] In some examples, the suspension frequency from the wheel target includes the following relationships: Among them, f H depending on Where λ is the surface wavelength and V is the vehicle speed; and W is the vehicle wheelbase.

[0015] In some examples, the control system is configured to reduce the guide wheel target suspension frequency relative to the surface frequency, wherein the amount of reduction in the guide wheel target suspension frequency is inversely proportional to the vehicle speed.

[0016] In some examples, the amount of reduction in the target suspension frequency of the guide wheel is proportional to the vehicle wheelbase divided by the vehicle speed.

[0017] In some examples, the control system is configured to control the degree to which the frequency of the trailing wheel target suspension increases and the degree to which the frequency of the guide wheel target suspension decreases based on the lifting center position target, wherein the lifting center position target controls the longitudinal position of the center of the vehicle's lifting motion.

[0018] In some examples, the suspension frequency from the wheel target includes the following relationships: Among them, f H depending on Where λ is the surface wavelength and V is the vehicle speed; and where P H The target is the center position of the rise and fall between 0 and the maximum value r; where W is the vehicle wheelbase; and where the front wheel target suspension frequency includes the following relationship:

[0019] In some examples, the control system is configured to determine the target position of the lifting center based on input received from the human-machine interface.

[0020] In some examples, the control system is configured to determine force requirements, which include at least one of the following: a trailing wheel force requirement for a trailing wheel actuator of an active suspension system, depending on the trailing wheel target suspension frequency; and a guide wheel force requirement for a guide wheel actuator of an active suspension system, depending on the guide wheel target suspension frequency.

[0021] In some examples, determining the trailing wheel force requirement includes: determining the trailing wheel target wheel rate based on the trailing wheel target suspension frequency; and determining the trailing wheel force requirement based on the trailing wheel target wheel rate.

[0022] In some examples, determining the guide wheel force requirement includes: determining the guide wheel target wheel rate based on the guide wheel target suspension frequency; and determining the guide wheel force requirement based on the guide wheel target wheel rate.

[0023] In some examples, determining the force requirement includes determining the relationship between the force requirement of the active suspension system and the sensed displacement, and wherein the control system is configured to implement this relationship in the spring controller function.

[0024] In some examples, determining the force requirement includes determining the relationship between the force requirement of the active suspension system and the sensed wheel travel speed, and wherein the control system is configured to implement the relationship with the sensed wheel travel speed in the damper controller function.

[0025] In some examples, the control system is configured to determine a time window in which the expected collision event occurs and to establish a relationship between the time window and the sensed wheel travel speed.

[0026] According to one aspect of the present invention, an active suspension system including a control system is provided.

[0027] According to one aspect of the invention, a vehicle including a control system or an active suspension system is provided.

[0028] According to one aspect of the invention, a method for controlling an active suspension system of a vehicle is provided, the method comprising: determining that the vehicle is traveling on or approaching a repeating surface undulation; determining a vehicle speed; determining an indication of the surface wavelength of the repeating surface undulation; and controlling the active suspension system to control at least one of a guide wheel suspension frequency and a follow wheel suspension frequency based on the vehicle speed and the surface wavelength.

[0029] According to one aspect of the invention, computer software is provided that, when executed, is configured to perform the method. According to another aspect of the invention, a non-transitory computer-readable medium is provided comprising computer-readable instructions that, when executed by a processor, cause the execution of any one or more of the methods described herein.

[0030] The one or more controllers may collectively include: at least one electronic processor having an electrical input for receiving information; and at least one electronic storage device electrically coupled to the at least one electronic processor and having instructions stored in the at least one electronic storage device; and wherein the at least one electronic processor is configured to access the at least one storage device and execute the instructions on the at least one storage device, thereby causing the control system to perform the method.

[0031] Within the scope of this application, it is expressly intended that the various aspects, embodiments, examples, and alternatives set forth in the foregoing paragraphs, claims, and / or the following description and drawings, and in particular their various features, may be employed independently or in any combination falling within the scope of the appended claims. That is, unless these features are incompatible, all embodiments and / or features of any embodiment may be combined in any manner and / or combination falling within the scope of the appended claims. The applicant reserves the right to amend any initially filed claim or accordingly file any new claim, including the right to modify any initially filed claim to subordinate to and / or incorporate any feature of any other claim, even if not initially claimed in this manner. Attached Figure Description

[0032] One or more embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which:

[0033] Figure 1 An example of a vehicle is shown;

[0034] Figure 2 An example of a vehicle on a repeating surface undulation is shown;

[0035] Figure 3 An example of a control system is shown;

[0036] Figure 4 An example of a non-transitory computer-readable storage medium is shown;

[0037] Figure 5 An example of a vehicle's active suspension system is shown;

[0038] Figure 6A , Figure 6B , Figure 6C It is a displacement-time graph showing the conversion of pitch motion into heave motion; and

[0039] Figure 7 An example of the method is shown. Detailed Implementation

[0040] Figure 1 An example of a vehicle 100 that can implement embodiments of the present invention is shown. In some, but not all, examples, vehicle 100 is a passenger vehicle, also known as a bus or automobile. In other examples, embodiments of the present invention can be implemented for other applications, such as industrial or commercial vehicles.

[0041] Figure 1 A coordinate system is also shown. The x-axis is the longitudinal axis. The rotation of the vehicle body about the x-axis, "R", is roll. The y-axis is the transverse axis. The rotation of the vehicle body about the y-axis, "P", is pitch. The z-axis is the vertical axis. The rotation of the vehicle body about the z-axis, "Y", is yaw.

[0042] In the example described in this article, assume that vehicle 100 is moving forward (+x) such that the front wheels of vehicle 100 are leading wheels and the rear wheels are trailing wheels. If vehicle 100 is moving backward, then the rear wheels will be leading wheels and the front wheels will be trailing wheels.

[0043] Figure 2 This is a simplified illustration of a vehicle 100 traveling on surface undulations having approximately the same surface wavelengths (e.g., peak-to-peak distances) as each other.

[0044] Figure 2 The diagram shows the body 102 (sprung mass), front wheels (e.g., right front FR), rear wheels (e.g., right rear RR) and the wheelbase W between them, as well as the suspension 104 including the front suspension 106 of the front wheels FR and the rear suspension 108 of the rear wheels RR.

[0045] As the front wheel FR rises from the trough to the crest, the change in surface angle compresses the front suspension 106 of vehicle 100. The front wheel FR shifts (travels) toward the vehicle body 102 as indicated by the upward arrow. The resulting peak displacement of the front wheel FR from the neutral (zero) position toward the vehicle body 102 is shown in... Figure 2 In the embedded chart 200 (solid line), the y-axis represents the magnitude of displacement and the x-axis represents time.

[0046] As the front wheel FR reaches the crest of the undulation, the front wheel FR will then begin to rebound. Assuming that the suspension damping of vehicle 100 is insufficient, the front suspension 106 will exceed its neutral position and reach a negative peak displacement upon full rebound.

[0047] If full rebound occurs very close to the next rise to the next crest, the next full collision will be more severe, and vehicle 102 may pitch sharply. If vehicle 100 is traveling at an inappropriate speed, resonance occurs, causing pitch to increase over time, which could lead to a body-to-ground impact or wheel bounce.

[0048] Without the implementation of this invention, the driver may be forced to drive at a set speed to avoid resonance, which may not be the speed the driver expects.

[0049] The rear wheel RR will closely follow the pattern of the front wheel FR, but with a slight lag, equal to the wheelbase length W divided by the vehicle speed V (see the dashed line in embedded chart 200). It is worth noting that if the rear wheel RR reaches full rebound 602 later than the front wheel FR, this will be perceived as a pitch change rather than a vertical (linear z-axis movement). Pitch changes are generally considered less comfortable than vertical changes for vehicle occupants.

[0050] The front suspension 106 has a natural frequency that depends not only on the stiffness of the front springs but also on the sprung mass on the front wheel FR. The rear suspension 108 also has an associated frequency, which can be higher to reduce the delay in the full rebound of the rear wheel RR. In passive suspensions, the frequency is predetermined at the factory to provide optimal ride quality and handling under normal usage conditions (e.g., a vehicle speed), but not necessarily under all usage conditions.

[0051] In embodiments of the present invention, the suspension is an active suspension system, which may consist of, for example, Figure 3 The control system 300 shown provides control. This enables dynamic control of the spring force and / or damping force, allowing the vehicle 100 to be driven over undulations at a range of speeds without excessive pitch motion.

[0052] Figure 3 The control system 300 includes a controller 301. In other examples, the control system 300 may include multiple controllers mounted on and / or external to the vehicle 100. In some examples, the control system 300 or controller 301 may be provided as part of the active suspension system 104.

[0053] Figure 3 The controller 301 includes: at least one processor 304; and at least one storage device 306 electrically coupled to the processor 304 and having instructions 308 (e.g., a computer program) stored therein, said at least one storage device 306 and instructions 308 being configured to utilize the at least one processor 304 to cause any one or more of the methods described herein to be executed. The processor 304 may have an interface 302, such as electrical input / output I / O or electrical input, for receiving information and interacting with external components, such as the active suspension system 104.

[0054] Figure 4A non-transitory computer-readable storage medium 400 containing instructions 308 (computer software) is shown.

[0055] Figure 5 An example implementation of the active suspension system 104 is shown.

[0056] The active suspension system 104 includes a left front active suspension 106 for the left front wheel FL, a right front active suspension 116 for the right front wheel FR, a left rear active suspension 108 for the left rear wheel RL, and a right rear active suspension 118 for the right rear wheel RR. The active suspension of each wheel of the vehicle 100 (e.g., quarter / angle) can be individually controllable.

[0057] The active suspension at each corner of vehicle 100 includes actuator 502.

[0058] Actuator 502 may be a hydraulic actuator, such as a hydraulic fluid-filled chamber containing a piston. One end of actuator 502 is connected to a wheel, and the other end is connected to the vehicle body 102. A second spring element 504 (e.g., a helical or pneumatic) may be in a balanced state and act in parallel with actuator 502.

[0059] When the vehicle suspension is undisturbed, the piston of the hydraulic actuator 502 is in a specific neutral position within the cavity.

[0060] For example, due to road disturbances that compress actuator 502, the piston can move in either direction within the chamber. The piston can discharge fluid from the chamber into a hydraulic circuit (not shown). The fluid exerts a restoring force against the piston's movement. Energy can be added to and / or extracted from actuator 502 by pumping fluid and / or by controlling valves to adjust the fluid pressure to either side of the piston.

[0061] Therefore, the control system 300 can dynamically control the restoring force of the piston resisting displacement based on the output force demand. This force is equivalent to the spring force of a coil spring resisting displacement. Dynamic control can change the force-displacement relationship to adapt to the driving scenario. Energy can be rapidly increased or removed, for example, within tens of milliseconds.

[0062] The dynamic damping characteristics of actuator 502 can be modified by controlling a fluid valve at the contraction point, which regulates the rate at which fluid is delivered into and out of actuator 502 by the movement of the piston. In some examples, the impact and rebound damping characteristics can be controlled independently.

[0063] Therefore, the force demand on actuator 502 can control the spring force and damping. To control the spring force, control system 300 can output a force demand that depends on the sensed wheel travel (wheel displacement / articulation relative to the vehicle body). To control the damping characteristics, control system 300 can output a force demand that depends on the sensed wheel travel speed on the wheel travel axle.

[0064] Wheel travel can be sensed, for example, by a wheel-to-body displacement sensor 514 (suspension displacement sensor). The wheel-to-body displacement sensor 514 is positioned at a point on the active suspension and can sense the position of the wheel along an arc defined by the suspension geometry. An example of the wheel-to-body displacement sensor 514 is a rotary potentiometer attached to a rod, one end of which is connected to the body 102, and the other end to a suspension link.

[0065] Wheel travel speed can be indicated by the rate of change of wheel position over time. Wheel travel speed can be sensed by integrating the wheel acceleration from the hub accelerometer 516 and / or by differentiating the wheel travel. A hub accelerometer 516 can be provided for each wheel and coupled to the unsprung mass of the vehicle 100. Similar to the wheel-to-body displacement sensor 514, the hub accelerometer 516 can also be considered a suspension displacement-based sensor, since the acceleration of the hub on the z-axis depends on the rate of change of suspension displacement.

[0066] In some examples, the control system 300 determines wheel travel and / or its associated derivatives more accurately by fusing information from the wheel-to-body displacement sensor 514 with information from the wheel hub accelerometer 516.

[0067] The above example relates to a hydraulic actuator 502, and in other embodiments, the actuator may be an electromagnetic actuator or a pneumatic actuator, etc.

[0068] exist Figure 5 In this configuration, the active suspension also includes a second spring element 504, such as a pneumatic spring, which enables control of the ride height. The control system 300 can be configured to pump gas (e.g., air) into or out of the pneumatic spring 504 to control the ride height. The air leveling function of the control system 300 seeks to maintain a set ride height regardless of vehicle load and achieves this by changing the volume of air and thus changing the air pressure to maintain the set ride height.

[0069] Alternatively or alternatively, the second spring element 504 may include a passive spring (e.g., a helical tube) or be omitted entirely. For example, the actuator 502 may control transient and long-term ride height at the cost of increased energy consumption.

[0070] In some examples, the force requirements transmitted to the active suspension or its lower-level controller are force requirements based on arbitration of requests from various requesters and information from various sensors.

[0071] Figure 5 Additional optional features that can interact with the control system 300 are shown for impact requirement calculation. These additional optional features include any one or more of the following:

[0072] - Wheel speed sensor 512 for each wheel. In the example implementation, wheel speed sensor 512 is part of the anti-lock braking system (ABS).

[0073] - Human-Machine Interface (HMI) 520. This refers to any of the various input devices and input / output devices available to the driver, such as touchscreens, displays, hardware switches / sliders / selectors, etc.

[0074] - At least one accelerometer 522 is coupled to the vehicle body 102 (sprung mass). Specific examples include a 3DOF or 6DOF inertial measurement unit (IMU). Examples are accelerometers or a set of multi-axis accelerometers.

[0075] - Position sensor 524, such as a Global Positioning System (GPS) sensor.

[0076] - A terrain detection sensor 526 is configured to detect surface terrain around vehicle 100. Examples include imaging sensors. Imaging sensors include cameras, lidar sensors, radar sensors, etc., or combinations thereof. Cameras, lidar sensors, and radar sensors provide images indicating terrain, which can be converted into 3D point clouds or discretized in some other way and used for functions such as crest detection. Sensors can be located around vehicle 100, each sensor having a different field of view. The field of view includes a forward view on the +x axis. If the method described herein is operable in reverse gear, the field of view may include a rearward view on the -x axis.

[0077] - Wireless communication interface 528 (e.g., radio interface) for vehicle-to-vehicle (V2V) and / or infrastructure-to-vehicle (V2I / I2V) communication. In some examples, communication interface 528 can implement location-related functions.

[0078] Figures 6A to 6C This is a suspension amplitude-time graph, showing how the active suspension system 104 can be controlled to reduce pitch changes of the vehicle body on repetitive surface undulations. Amplitude represents the displacement of the wheel relative to the vehicle body.

[0079] Figure 6A This is a reference scenario in which an embodiment of the present invention is not employed. The vehicle 100 shown has a surface wavelength λ.S It travels at a speed of V1 on the surface undulations. The surface frequency is f. S1 Given by equation (1)

[0080]

[0081] The front suspension 106 and 116 at the front (guide) wheel of vehicle 100 have a natural frequency f F1 This natural frequency depends on the spring stiffness and the sprung mass on the front wheels FL and FR. To avoid excessive vehicle pitch, the driver can adjust the speed at f. F1 =f S1 Travel at that speed.

[0082] Since the full rebound 604 of the rear suspensions 108 and 118 occurs after the full rebound 602 of the front suspensions 106 and 116, the vehicle 100 will experience pitch changes regardless, even if the driver is limited to a specific speed. This is because: for a given vehicle speed, the natural frequency f of the rear suspensions 108 and 118... R1 It may not be high enough for the timing of the two rebounds, 602 and 604, to overlap.

[0083] Figure 6B This is a scenario in which an embodiment of the present invention is employed. Vehicle 100 travels at a faster speed V2. As a result, the surface frequency f S2 Larger than before. The control system 300 changes the natural frequency of the front suspension 106, 116 from f F1 Change to f F2 , making f F2 with f S2 Matching. Therefore, despite changes in vehicle speed, the natural frequencies of the front suspension 106 and 116 still match the surface frequencies.

[0084] exist Figure 6B In addition, considering the increase in the natural frequencies of the front suspension 106 and 116, the natural frequencies of the rear suspension 108 and 118 have also increased to a level higher than their previous values ​​f. R1 large f R2 .

[0085] Conversely, if vehicle 100 is traveling slower, at least one of the suspension frequencies can be lowered towards a lower surface frequency.

[0086] Optionally and as Figure 6B As shown, the natural frequencies of the rear suspensions 108 and 118 have been further increased so that the full rebound 604 of the rear suspensions 108 and 118 is at least partially aligned with the full rebound 602 of the front suspensions 106 and 116. In this example, f F2 =f S2 And fR2 >f S2 &f F2 In other words, the rear wheel target suspension frequency f R2 Greater than the surface frequency f S2 And greater than the target suspension frequency f of the front wheels F2 This further reduces pitch motion by converting pitch motion into vertical motion. The location of the center of vertical motion is shown by target 606 in the vehicle schematic diagram shown on the right side of the chart, indicating that the rear seats achieve optimal passenger comfort.

[0087] exist Figure 6C In the example, vehicle 100 follows Figure 6A Travel at the original speed V1. Figure 6C This illustrates how the natural frequencies of the front suspensions 106 and 116 and the rear suspensions 108 and 118 can be altered to varying degrees to change the position of the center of the lifting motion within the vehicle's wheelbase. The natural frequencies f of the front suspensions 106 and 116 are shown. f3 with f F1 Compared to reduction, the natural frequency f of the rear suspension... R3 with f R1 Same. Front wheel target suspension frequency f F3 Less than the surface frequency f S1 .because Figure 6C As shown in target 606, the center of the lifting motion 606 moves further forward in the vehicle 100 to coincide with the front seats, thereby providing comfort for the front passengers.

[0088] Therefore, the natural frequency can be changed based on the surface frequency to reduce pitch changes, and / or the longitudinal position of the center of the lifting motion can be controlled.

[0089] Therefore, based on Figure 6B and Figure 6C A method is provided, the method comprising:

[0090] Determine that vehicle 100 is traveling on or approaching a repeating surface undulation;

[0091] Determine the vehicle speed;

[0092] Indicators for determining the surface wavelength of repeating surface undulations; and

[0093] The active suspension system 104 is controlled based on vehicle speed and surface wavelength to control at least one of the front wheel suspension frequency and the rear wheel suspension frequency.

[0094] Figure 7 This is a flowchart illustrating the implementation method 700 in the example.

[0095] At operation 702, method 700 includes determining, based on the satisfaction of an entry condition, that the vehicle 100 is traveling on or approaching a repeating surface undulation. In other words, a repeating long-wave sinusoidal surface has been directly or indirectly sensed.

[0096] Various sources of information, either individually or in combination, can help make this determination.

[0097] The primary information source is response information indicating changes in wheel travel and / or vehicle body motion. This response information can be received from one or more suspension displacement sensors 514, 516 and / or from the vehicle body accelerometer 522. Frequency analysis can reveal a correlated periodicity in the vertical acceleration. This periodicity can be correlated with surface frequency and / or surface wavelength.

[0098] The control system 300 can improve the confidence level of its response information indicating surface undulations by checking at least one of the following:

[0099] - Vehicle 100 is moving on the ground;

[0100] -Vertical acceleration is not isolated from a specific quarter of the vehicle;

[0101] - The movement of the guide shaft follows the movement of the shaft.

[0102] - Vertical acceleration is independent of unrelated motions such as yaw / roll.

[0103] Another source of information is, for example, a set of suspension displacement sensors 514 for each wheel / corner / quarter of vehicle 100. Similar frequency analysis can be performed. The control system 300 can check whether the rear suspensions 108, 118 follow the movement of the front suspensions 106, 116.

[0104] The crest detection sensor 526 enables at least some prior detection, which can optionally be confirmed later by reactive sensing. In the example implementation, the crest detection system uses a 3D point cloud indicating the terrain derived from measurements using the terrain detection sensor 526. During the predicted / determined path of vehicle 100, crests can be detected as discontinuities in the point cloud-based terrain. In this example, crests are detected simultaneously (if they are both in the field of view) or sequentially in time. The spatial and / or temporal separation of crests can be analyzed, for example, using frequency analysis to detect surface frequencies and / or surface wavelengths and satisfy operation 702.

[0105] The discontinuity-based peak detection algorithm can detect discontinuities as boundaries between terrain and areas where terrain is expected to exist (due to being within the sensing range of the terrain detection sensor 526), ​​but is not present, for example, due to peaks obscuring the terrain.

[0106] The peak detection system can also determine whether the slope information preceding the discontinuity indicates that the slope value of the terrain preceding the discontinuity at a predetermined distance exceeds a predetermined threshold in the upward sloping direction (+z).

[0107] Therefore, peak detection may require detecting both discontinuities and the upward slope above a threshold preceding the discontinuity. Other methods for peak detection are also useful.

[0108] Communication interface 528, such as V2V / V2I / I2V interface, can provide vehicle 100 with information indicating that vehicle 100 is on or near repeating surface undulations.

[0109] Location information from position sensor 524, such as GPS, can be used to determine, based on historical data, whether vehicle 100 is in or near an area with repetitive surface undulations. For example, vehicle 100 can learn to associate repetitive surface undulations with specific locations over multiple trips.

[0110] The entry conditions for operation 702 may further require that the repeating surface undulations have certain characteristics, examples of which will be described below.

[0111] One characteristic is that the surface frequency and vehicle speed for a given surface wavelength cannot be too high. If the surface frequency is high, it may not be possible to raise the suspension frequency sufficiently to produce a significant beneficial effect.

[0112] Therefore, a surface frequency-related upper threshold can be set in the control system 300. In the example, the surface frequency-related upper threshold is configured to exceed surface frequencies in the range of approximately 3 Hz to approximately 4 Hz. This threshold is less than the frequency associated with rough roads. The threshold can be implemented in various ways, such as a frequency (Hz) threshold, or alternatively, as a combination of vehicle speed and surface wavelength thresholds, or as a count peak within a time window, etc.

[0113] Another characteristic is that the surface frequency is not too low. A low surface frequency allows the vehicle suspension to stabilize before the next undulation. Therefore, a lower threshold related to the surface frequency can be set in the control system 300. In the example, the lower threshold related to the surface frequency corresponds to a surface frequency in the range of approximately 0.2 Hz to approximately 0.4 Hz, for example, 0.25 Hz.

[0114] Another feature is the appearance of multiple fluctuations within the time window T. This prevents false alarms for speed bumps, hump bridges, etc., with relatively wide intervals.

[0115] Another characteristic is that the fluctuations are not too shallow, as indicated by the sensed amplitude.

[0116] Once the entry conditions are met, method 700 determines an indication of the surface wavelength at operation 708. The indication of the surface wavelength may depend on sensor information from data block 704 and / or historical data from block 706. The information and techniques can be as described above. The surface wavelength can be monitored continuously.

[0117] In another embodiment, operation 708 can be performed before the entry conditions for operation 702 are met. Operation 702 can be performed using the surface wavelength information determined at operation 708.

[0118] In at least some examples, the active suspension system 104 is controlled based on an indication of the surface frequency. Therefore, at operation 710, method 700 determines the surface frequency f. S It is the vehicle speed V (data block 709) divided by the surface wavelength λ from operation 708. S Proportional:

[0119]

[0120] The vehicle speed V can be determined by the user (e.g., the driver) or by driver assistance systems (e.g., cruise control, autonomous mode).

[0121] The following operation of method 700 is configured to control the suspension frequency to convert body pitch changes into height changes.

[0122] In a typical implementation, the surface frequency is considered as the target rise and fall frequency f. H (Operation 714).

[0123] Optionally, operation 714 provides for the use of another frequency if necessary. O (Data block 712) provides the opportunity to modify or overwrite the target rise / fall frequency. Operation 714 can be implemented as an arbitration function:

[0124] f H =f(f S f O (3)

[0125] Other frequency requirements f O It can be based on driver selection or sensing. This provides greater flexibility, although specific examples are beyond the scope of this disclosure.

[0126] Then, the flowchart is divided into front suspension calculations and rear suspension calculations. The front suspension branch starts by determining the target front wheel suspension frequency f. F Operation 718 begins. The rear suspension branch starts from determining the target rear wheel suspension frequency f. R The operation begins at 724.

[0127] Operations 718 and 724 may depend on data block 716, but the implementation without data block 716 will be described first. In this implementation, the target front wheel suspension frequency f F It will be modified to be equal to the target rise and fall frequency f if necessary. H In at least some examples, it is equal to the surface frequency f. S Rear wheel target suspension frequency f R Will be modified:

[0128]

[0129] Equation 4 shows that the target rear suspension frequency is increased relative to the surface frequency / target lift frequency by an amount proportional to the wheelbase and inversely proportional to the vehicle speed V (from data block 717). The target rear suspension frequency is increased to align the rear suspension full rebound 604 with the front suspension full rebound 602. This compensates for the time delay (W / V) of the rear wheels RL, RR behind the front wheels FL, FR, thereby converting the vehicle's pitch motion into lift motion. Figure 6B The effect of this method is shown in the figure.

[0130] exist Figure 6C In the alternative implementation shown, instead of increasing the rear wheel suspension frequency, the target front wheel suspension frequency is decreased to align the front rebound 602 with the rear rebound 604. The target rear (non-front) wheel suspension frequency f R This will be equal to the target rising and falling frequency f. H :

[0131]

[0132] The substitution methods in equations (4) and (5) correspond to, for example, Figure 6B , Figure 6C Different lifting center positions 606 in the vehicle 100 shown. In a further implementation, the lifting center position target P from data block 716 can be used. H To control the relative target suspension frequencies of the front and rear wheels, the center of the lifting motion of vehicle 100 is configured to be at a longitudinal position 606 within or beyond the vehicle's wheelbase to provide comfort for the row of seats / cargo areas with rear wheel suspension. Target lifting center position P H It has values ​​between the minimum value (e.g., r = 0) and the maximum value r (e.g., r = 1). The relationship then becomes:

[0133]

[0134]

[0135] Therefore, P can be modified within the wheelbase range. HThis is to provide maximum comfort for either the front-seat occupants or the rear-seat occupants. H Configuration can be performed using the HMI 520, either through or via the HMI 520's vehicle mode, and / or via occupant sensing. The driver's vehicle may cause P... H Shift backward to benefit rear passengers. If the driver is the only occupant, P H It may shift forward.

[0136] The remaining calculations convert the target frequency into actuator force requirements. In method 700, but not necessarily in all examples, this conversion uses an analysis function based on known geometric parameters of the vehicle suspension.

[0137] For the front suspensions 106 and 116, operation 720 converts the target suspension frequency of the front wheels into the target wheel speed of the front wheels, and operation 722 converts the target wheel speed of the front wheels into the front suspension force demand.

[0138] For the rear suspensions 108 and 118, operation 726 converts the target suspension frequency of the front wheels into the target wheel speed of the front wheels, and operation 728 converts the target wheel speed of the front wheels into the front suspension force demand.

[0139] The following provides an example of the conversion. Front wheel target wheel speed K F (Each angle) is determined based on the following relationship:

[0140]

[0141] Where M F This is the front wheel sprung mass estimate (per corner). The sprung mass estimate can be a fixed value stored in memory or a variable. If the sprung mass estimate is a variable, its value can be based at least in part on a measurement. Examples of sprung mass measurements for a given corner include measuring the steady-state pneumatic / hydraulic pressure in actuator 502 or the second spring element 504.

[0142] The wheel speed has a passive component (e.g., due to the second spring element 504, bushing, etc.) and an active component. The active component needs to be controlled. Therefore, the target active wheel speed K for the front wheels can be determined. F(Aclive) (Each corner):

[0143] K F(Active@Wheel) =K F -K F(Base) (9)

[0144] Where K F(Base) It is the instantaneous passive front wheel speed (per corner):

[0145] K F(Base) =f(KF(Base：Map) Δz F (10)

[0146] Where K F(Base：Map) It is the mapping of the basic wheel speed of the front wheel, and where Δz F It is the displacement estimate (per angle) of the front wheel relative to the vehicle body, which is estimated by sensor 514, indicating the wheel travel.

[0147] Since wheel rate can be affected by ride height, the front wheel base wheel rate mapping can include the relationship between wheel rate and ride height-related parameters. In the example, ride height-related parameters include the pressure and / or volume of the second spring element 504.

[0148] Once the target driving wheel speed of the front wheel is known, the gain parameter (K) at actuator 502 is... F(Active@Strut) It can be calculated based on the target active wheel speed:

[0149] K F(Active@Strut) =K F(Active@Wheel) ×MR (Strut) (11)

[0150] Among them MR (Strut) It is the motion ratio of the active strut (actuator) of the front wheel known to the control system 300.

[0151] Based on the gain parameter, determine the required active force contribution at this angle:

[0152] F F =K F(Active@Strut) ×Δz F (12)

[0153] Equation 12 defines the force demand as a mapping (relationship). That is, the force demand is calculated based on the gain parameter related to the undulations multiplied by the sensed wheel travel (wheel displacement / articulation relative to the vehicle body). When there is no wheel travel, the behavior of the active suspension system 104 is no different from normal. When the suspension is subjected to undulations, the value of the gain parameter determines the response.

[0154] The gain parameter can be viewed as changing the natural frequency of actuator 502, similar to changing the stiffness of an equivalent passive spring. Since the response of the active suspension system 104 is sufficient to change the force rapidly, the stiffness can also be non-linear with respect to wheel travel.

[0155] By using known or measured information about the rear suspension 108, 118 to convert the target rear suspension frequency into the rear suspension force demand, the same equations (8) to (12) can be applied to the rear wheels RL, RR in operations 726 to 728.

[0156] Alternatively, the gain parameter from Equation 11 can be applied to the damping behavior in the function of the damper controller:

[0157] F F =K F(Active@Strut) ×WTV (13)

[0158] WTV is the wheel travel speed.

[0159] This will cause actuator 502 to substantially critically dampen the oscillations of the active suspension in response to the surface frequency. This reduces or avoids overshoot during rebound, thereby reducing or eliminating the pitch changes shown in the previous diagram. Therefore, the vehicle's pitch motion is reduced.

[0160] Note that in damper control mode, no additional energy is required. Force demand is in the passive quadrant, meaning the road surface provides energy to the damper. Therefore, aspects of this invention are applicable to semi-active active suspension systems, such as active damper systems that do not require additional energy to control spring stiffness.

[0161] For damper control, if the force demand can be configured separately for the collision and rebound damper rates, the force demand in Equation 13 can be applied only to rebound. However, depending on what external excitation occurs when damping is increased, this can lead to secondary ride discomfort, such as a slam, wheel bounce, swaying, or shuddering. Therefore, the control system 300 can advantageously provide a time window for the force demand to terminate at the start of the next anticipated collision event (rising from the trough to the crest). Thus, the suspension is agile and comfortable when compressed by the next rise. As vehicle speed increases and / or surface wavelength decreases, the time window can be shortened based on the monitored surface wavelength / frequency.

[0162] Time window control means that the front actuator and the rear actuator responsible for damping are strengthened sequentially at the front and then at the rear to counteract resonance.

[0163] When performing method 700 and if the vehicle height is controllable, the second spring element 504 and / or actuator 502 can be controlled to raise the vehicle height, thereby reducing the chance of the vehicle body contacting the ground.

[0164] After the force requirement has been met, method 700 can then loop back to an earlier operation, such as determining the surface wavelength (operation 708). By continuously looping method 700 until the exit condition is met, the confidence level regarding the calculated surface wavelength / frequency will increase, and variations in surface wavelength and / or vehicle speed can also be compensated for.

[0165] Exit conditions can be continuously monitored. Exit conditions can be based on the same variables as entry conditions, with or without hysteresis. For example, method 700 can be disabled (e.g., mixed or canceled) if an upper threshold related to surface frequency is exceeded and / or if a lower threshold related to surface frequency is exceeded.

[0166] The advantages of the method described in this paper are that the user, such as the driver, has the freedom to choose the vehicle speed, and Equation 2 forward compensates for speed changes, thereby providing a good level of comfort and a reduced probability of vehicle-to-ground contact. When driving on undulating terrain, the method described in this paper provides a smaller trade-off between vehicle speed and comfort.

[0167] For the purposes of this disclosure, it should be understood that the controllers described herein may each include a control unit or computing device having one or more electronic processors. A vehicle and / or its systems may include a single control unit or electronic controller, or alternatively, different functions of the controller may be embodied in or hosted in different control units or controllers. A set of instructions may be provided, which, when executed, cause the controller or control unit to implement the control techniques (including the methods described herein). The set of instructions may be embedded in one or more electronic processors, or alternatively, the set of instructions may be provided as software to be executed by one or more electronic processors. For example, a first controller may be implemented in software running on one or more electronic processors, and one or more other controllers may also be implemented in software running on one or more electronic processors, optionally in software running on the same one or more processors as the first controller. However, it should be understood that other arrangements are also useful, and therefore, this disclosure is not intended to be limited to any particular arrangement. In any case, the aforementioned set of instructions may be embedded in a computer-readable storage medium (e.g., a non-transitory computer-readable storage medium), which may include any mechanism for storing information in a form readable by a machine or electronic processor / computing device, including but not limited to: magnetic storage media (e.g., floppy disks), optical storage media (e.g., CD-ROMs), magneto-optical storage media, read-only memory (ROM), random access memory (RAM), erasable programmable memory (e.g., EPROMs and EEPROMs), flash memory, or electrical media or other types of media used to store such information / instructions.

[0168] It should be understood that various changes and modifications can be made to this invention without departing from the scope of this application.

[0169] Figure 7The operations shown may represent steps in a method and / or code segments in computer program 308. The illustration of a specific order of operations does not necessarily imply a required or preferred order, and the order and arrangement of operations can vary. Furthermore, some steps may be omitted.

[0170] Although embodiments of the invention have been described in the foregoing with reference to various examples, it should be understood that modifications may be made to the given examples without departing from the scope of the claimed invention.

[0171] The features described in the preceding description may be used in combinations other than those explicitly described. While functionality has been described with reference to certain features, those functions may be performed by other features regardless of whether they are described. Similarly, while features have been described with reference to certain embodiments, those features may exist in other embodiments regardless of whether they are described.

[0172] While efforts have been made to draw attention in the foregoing description to these features of the invention as particularly important, it should be understood that the applicant reserves the right to claim protection with respect to any patentable feature or combination of features shown prior to this reference and / or in the accompanying drawings, whether or not they are particularly emphasized.

Claims

1. A control system configured to control an active suspension system of a vehicle, the control system comprising one or more controllers, wherein, The control system is configured to: Determine that the vehicle is traveling on or approaching the repeating surface undulations; Determine the vehicle speed; Indication of the surface wavelength of the repeating surface undulations; The active suspension system is controlled based on the vehicle speed and the surface wavelength to control at least one of the guide wheel suspension frequency and the driven wheel suspension frequency; Determine the surface frequency, wherein the surface frequency is proportional to the vehicle speed divided by the surface wavelength, and wherein the control of the active suspension system is based on the surface frequency; and The target suspension frequency of the trailing wheel and / or the target suspension frequency of the guide wheel are determined based on the surface frequency.

2. The control system according to claim 1, wherein, The indication of the surface wavelength depends on information from at least one of the following sensors: accelerometer; A set of suspension displacement sensors; Peak detection system; A communication interface configured for vehicle-to-vehicle and / or infrastructure-to-vehicle communication; or A position sensor, wherein the control system is configured to retrieve historical data using position data from the position sensor.

3. The control system according to claim 1 or 2, wherein the control system is configured to disable control of the active suspension system when the surface frequency drops below a lower threshold related to the surface frequency.

4. The control system according to claim 1 or 2, wherein the control system is configured to disable control of the active suspension system if the surface frequency exceeds an upper threshold related to the surface frequency.

5. The control system according to claim 1 or 2, wherein the control system is configured to control at least one of the following: controlling the trailing wheel target suspension frequency to be greater than the surface frequency; and controlling the guide wheel target suspension frequency to be less than the surface frequency.

6. The control system according to claim 1 or 2, wherein the control system is configured to increase the target suspension frequency of the driven wheel relative to the surface frequency, wherein, The increase in the suspension frequency of the target wheel is inversely proportional to the vehicle speed.

7. The control system of claim 6, wherein the control system is configured to reduce the target suspension frequency of the guide wheel relative to the surface frequency, wherein, The reduction in the target suspension frequency of the guide wheel is inversely proportional to the vehicle speed.

8. The control system according to claim 6 or 7, wherein the control system is configured to control the degree of increase in the trailing wheel target suspension frequency and the degree of decrease in the guide wheel target suspension frequency based on the target lifting center position, wherein, The lifting center position target controls the longitudinal position of the center of the vehicle's lifting motion.

9. The control system of claim 8, wherein the control system is configured to determine the target position of the lifting center based on input received from the human-machine interface.

10. The control system according to any one of claims 5 to 9, wherein the control system is configured to determine a force requirement, the force requirement comprising at least one of the following: The trailing wheel force requirement for the trailing wheel suspension actuator of the active suspension system depends on the trailing wheel target suspension frequency; and The guide wheel force requirement for the guide wheel suspension actuator of the active suspension system depends on the target suspension frequency of the guide wheel.

11. An active suspension system comprising a control system according to any one of the preceding claims.

12. A vehicle comprising a control system according to any one of claims 1 to 10 or an active suspension system according to claim 11.

13. A method for controlling an active suspension system of a vehicle, the method comprising: Determine that the vehicle is traveling on or approaching the repeating surface undulations; Determine the vehicle speed; Indication of the surface wavelength of the repeating surface undulations; The active suspension system is controlled based on the vehicle speed and the surface wavelength to control at least one of the guide wheel suspension frequency and the driven wheel suspension frequency; Determine the surface frequency, wherein the surface frequency is proportional to the vehicle speed divided by the surface wavelength, and wherein the control of the active suspension system is based on the surface frequency; and The target suspension frequency of the trailing wheel and / or the target suspension frequency of the guide wheel are determined based on the surface frequency.

14. A computer-readable storage medium having a computer program stored thereon, wherein, The computer program, when executed, is configured to perform the method according to claim 13.

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