Friction estimation for vehicle

Abstract

The invention provides friction estimation for a vehicle. A vehicle includes at least one wheel that drives a tire to move the vehicle along a support. The vehicle includes a radio frequency (RF) transceiver that transmits an RF signal toward the support and measures a reflected signal. The vehicle includes a drive unit that drives rotation of the at least one wheel. The vehicle includes a control circuit in communication with the RF transceiver and the drive unit. The control circuit is configured to: estimate a humidity condition of the support based on the reflected signal; determining a level of friction between the tire and the support based on the humidity condition; and transmitting an output to adjust a force between the tire and the support in response to the friction level.

Description

Technical Field

[0001] The present disclosure relates generally to friction estimation for a vehicle and, more particularly, to systems and methods for determining friction conditions between a vehicle tire and a supporting surface using radio frequency signal processing. Background Art

[0002] Conventionally, traction control systems may use active feedback to detect friction. Summary of the invention

[0003] According to a first aspect of the present disclosure, a vehicle includes at least one wheel that drives a tire to move the vehicle along a support. The vehicle includes a radio frequency (RF) transceiver that transmits an RF signal toward the support and measures a reflected signal. The vehicle includes a drive unit that drives the rotation of the at least one wheel. The vehicle includes a control circuit that communicates with the RF transceiver and the drive unit. The control circuit is configured to: estimate a humidity condition of the support based on the reflected signal; determine a friction level between the tire and the support based on the humidity condition; and transmit an output in response to the friction level to adjust a force between the tire and the support.

[0004] Embodiments of the first aspect of the present disclosure may include any one or a combination of the following features:

[0005] - the control circuit is configured to control the RF transceiver to output the RF signal with a first phase and compare a second phase of the reflected signal with the first phase to detect a phase difference, and estimate the humidity condition of the support based on the phase difference;

[0006] - the control circuit is configured to determine a propagation delay based on the phase difference;

[0007] - the support is soil, and the control circuit is configured to estimate a soil compaction level based on the propagation delay;

[0008] - the control circuit is further configured to determine a target delay for the RF signal based on the distance and compare the target delay with the propagation delay to estimate the humidity condition;

[0009] - the control circuit is configured to detect an amplitude difference between the RF signal and the reflected signal and to determine a reflection coefficient of the support based on the amplitude difference;

[0010] - the support is soil, and the control circuit is configured to estimate the soil compaction level based on the reflection coefficient;

[0011] - the control circuit is configured to determine a shear modulus of the support based on the phase difference;

[0012] - the control circuit is configured to determine a friction angle based on the phase difference;

[0013] - a braking system configured to selectively limit rotation of the tire in response to the wetness conditions;

[0014] - the control circuit comprises: a motion control module having a plurality of modes configured to drive the at least one wheel at a plurality of speeds; and an RF phasing module configured to detect a phase difference between the RF signal and the reflected signal to estimate the humidity condition; and

[0015] - the RF transceiver comprises: an RF transmitter that transmits the RF signal toward the support; and an RF receiver that measures the reflected signal reflected by the support.

[0016] According to a second aspect of the present disclosure, a vehicle includes at least one wheel that drives a tire to move the vehicle along a support. The vehicle includes a radio frequency (RF) transceiver that transmits an RF signal toward the support and measures a reflected signal. The vehicle includes a drive unit that drives the rotation of the at least one wheel. The vehicle includes a control circuit that communicates with the RF transceiver and the drive unit. The control circuit is configured to control the RF transceiver to output the RF signal with a first phase. The control circuit is configured to compare a second phase of the reflected signal with the first phase to detect a phase difference. The control circuit is configured to: estimate a humidity condition of the support based on the phase difference; determine a friction level between the tire and the support based on the humidity condition; and transmit an output in response to the friction level to adjust a force between the tire and the support.

[0017] Embodiments of the second aspect of the present disclosure may include any one or a combination of the following features:

[0018] - the control circuit is configured to detect an amplitude difference between the RF signal and the reflected signal and to determine a reflection coefficient of the support based on the amplitude difference;

[0019] - the control circuit is configured to determine a propagation delay based on the phase difference;

[0020] - the control circuit is further configured to determine a target delay for the RF signal based on the distance and compare the target delay with the propagation delay to estimate the humidity condition;

[0021] - a braking system configured to selectively limit rotation of the tire in response to the friction level; and

[0022] -The control circuit comprises: a motion control module having multiple modes configured to drive the at least one wheel at multiple speeds; and an RF phasing module configured to detect a phase difference between the RF signal and the reflected signal to estimate the humidity condition.

[0023] According to a third aspect of the present disclosure, a vehicle includes at least one wheel that drives a tire to move the vehicle along soil. The vehicle includes a radio frequency (RF) transmitter that transmits an RF signal toward the soil. The vehicle includes an RF receiver that receives a reflected signal reflected from the soil; and a drive unit that drives the rotation of the at least one wheel. The vehicle includes a control circuit that communicates with the RF transmitter, the RF receiver, and the drive unit. The control circuit is configured to control the RF transmitter to output the RF signal at a first phase. The control circuit is configured to compare a second phase of the reflected signal with the first phase to detect a phase difference, and estimate the moisture condition of the soil based on the phase difference. The control circuit is configured to determine a friction level between the tire and the soil based on the moisture condition; and transmit an output in response to the friction level to adjust the force between the tire and the support.

[0024] Embodiments of the third aspect of the present disclosure may include any one or a combination of the following features:

[0025] - a braking system configured to selectively limit rotation of the tire in response to the friction level.

[0026] These and other features, advantages and objectives of the present disclosure will be further understood and appreciated by those skilled in the art by referring to the following description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In the attached picture:

[0028] Figure 1 is a perspective view of a vehicle incorporating a radio frequency detection system for optimizing traction control for the vehicle;

[0029] Figure 2is a functional block diagram of a friction estimation system for a vehicle, illustrating an RF signal transmitted to a support of the vehicle and an RF signal reflected from a support of the vehicle;

[0030] FIG. 3A to FIG. 3D are four exemplary cross sections of a support for a vehicle, illustrating differences in reflected RF signals based on the properties of the support;

[0031] Figure 4 is a block diagram of a traction control system for a vehicle according to an aspect of the present disclosure; and

[0032] Figure 5 is a process flow diagram of a traction control system for a vehicle according to an aspect of the present disclosure. DETAILED DESCRIPTION

[0033] Reference will now be made in detail to the preferred embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same or similar parts. In the drawings, the depicted structural elements may or may not be drawn to scale, and certain parts may or may not be enlarged relative to other parts for the purpose of emphasis and understanding.

[0034] For the purpose of this description, the terms "upper", "lower", "right", "left", "rear", "front", "vertical", "horizontal" and their derivatives shall be used in conjunction with Figure 1 The present invention relates to the concept of orientation in the present invention. However, it should be understood that the concept can present various alternative orientations unless expressly specified to the contrary. It should also be understood that the specific devices and processes shown in the drawings and described in the following specification are merely exemplary embodiments of the inventive concepts defined in the appended claims. Therefore, unless the claims expressly state otherwise, specific dimensions and other physical characteristics related to the embodiments disclosed herein should not be considered limiting.

[0035] The embodiments illustrated herein reside primarily in combinations of method steps and apparatus components related to friction estimation for a vehicle. Therefore, apparatus components and method steps have been represented, where appropriate, by conventional symbols in the drawings, and only those specific details relevant to understanding the embodiments of the present disclosure are shown so as not to obscure the present disclosure with details that are readily apparent to one of ordinary skill in the art having the benefit of the description herein. In addition, like reference numerals in the specification and drawings represent like elements.

[0036] As used herein, the term "and / or" when used with a list of two or more items means that any one of the listed items may be employed alone, or any combination of two or more of the listed items may be employed. For example, if a composition is described as containing components A, B, and / or C, the composition may contain: only A; only B; only C; a combination of A and B; a combination of A and C; a combination of B and C; or a combination of A, B, and C.

[0037] As used herein, the term "about" means that the amount, size, formula, parameter and other quantities and characteristics are not exact, nor do they need to be exact, but may be approximate and / or larger or smaller as needed to reflect tolerances, conversion factors, rounding, measurement errors, etc. and other factors known to those skilled in the art. When the term "about" is used to describe the endpoints of a value or range, the disclosure should be understood to include the specific value or endpoint involved. Regardless of whether the endpoints of a numerical value or range in this specification are described as "about", the endpoints of the numerical value or range are intended to include two embodiments: one modified by "about" and one not modified by "about". It should also be understood that the endpoints of each range in the range are significant in relation to the other endpoint and independently of the other endpoint.

[0038] As used herein, the terms "substantially," "substantially," and variations thereof are intended to indicate that the feature being described is equal to or approximately equal to a value or description. For example, a "substantially planar" surface is intended to indicate a planar or approximately planar surface. Additionally, "substantially" is intended to mean that two values ​​are equal or approximately equal. In some embodiments, "substantially" may indicate that values ​​are within about 10% of each other, such as within about 5% of each other, or within about 2% of each other.

[0039] Unless expressly indicated to the contrary, as used herein, the terms "the," "a," or "an" mean "at least one" and should not be limited to "only one." Thus, for example, reference to "a component" includes embodiments having two or more such components unless the context clearly indicates otherwise.

[0040] Overall reference Figures 1 to 5, a traction control system 10 using RF processing provides enhanced motion of a vehicle 12 along a support 14. The support 14 may include any suitable contact surface, such as a pavement or off-road surface. In general, a proactive method of controlling vehicle motion is provided by actively scanning an area 16 outside the vehicle 12 via RF and measuring the RF returned from the outside area 16. For example, an RF transmission signal 18 may be transmitted from an RF transmitter 20, and an RF receiver 22 may measure a reflected RF signal 24 in response to the RF transmission signal 18 reflecting from the support 14. The measurements made may be applied to various qualities of the reflected RF signal 24. Based on the difference between the RF transmission signal 18 and the reflected RF signal 24, the traction control system 10 may classify the surrounding environment of the vehicle 12, and more specifically the surface condition of the support 14. Thus, by using RF control, the traction control system 10 may proactively adjust various aspects for maintaining traction between the vehicle 12 and the support 14, thereby limiting uncomfortable reactions to changes in surface friction conditions.

[0041] Now more specifically refer to Figure 1 , the vehicle 12 incorporates a plurality of RF devices 26 configured to transmit and / or receive RF signals. The RF devices 26 may be pre-installed RF devices 26, such as ultra-wideband (UWB) transceivers disposed on a front or rear dashboard 28 of the vehicle 12, for detecting blind spots and / or cross-traffic conditions. The RF devices 26 may be positioned to capture friction information regarding a support 14 in front of or in front of the vehicle 12. As shown, the RF devices 26 may also or alternatively be disposed along a side 30 of the vehicle 12 for capturing friction conditions of an area of ​​the exterior area 16 at the side 30 of the vehicle 12. Typically, the RF devices 26 are used to collect friction information regarding a support 14 on which the vehicle 12 is disposed and / or toward which it is moving.

[0042] The vehicle 12 includes a plurality of wheels 32, each of which is configured to drive a tire 34 to move the vehicle 12 along the support 14. As will be further described with reference to subsequent figures, each wheel 32 can be driven by a drive unit 96 ( Figure 4 ) drive unit, which includes a motor or other drive mechanism. In general, the traction control system 10 is configured to estimate the friction conditions between the tires 34 and the support surface 38 of the support 14, and control the drive unit 96 or another vehicle system in response to the friction of the friction conditions. For example, when moving through muddy terrain, the RF device 26 can detect the moisture content and / or compactness level of the support 14 (e.g., soil, gravel), and reduce or increase the revolutions per minute (RPM) of one or more of the plurality of wheels 32 to move the vehicle 12 in the direction of motion 50.

[0043] Continue to refer Figure 1 and Figure 2 , auxiliary detection sources 40, 42, 44 (such as cameras 40, radio detection and ranging sensors (radar 42), light detection and ranging sensors (lidar 44), and / or any other detection sources) may be coupled to the vehicle 12 for monitoring an area outside the vehicle 12. In a non-limiting example, the auxiliary detection sources 40, 42, 44 are configured to detect the distance between the RF device 26 and the support 14 to provide calibration of the RF device 26. For example, the difference between the reflected RF signal 24 and the RF transmission signal 18 may be based at least in part on the distance from the RF device 26 and the support surface 38. The auxiliary detection sources 40, 42, 44 may be referred to as time-of-flight devices that are configured to detect the distance from the vehicle 12 to the support 14 along the path of RF communication. In some examples, the RF device 26 is configured to operate in a first mode for friction estimation and a second mode for distance detection. In this example, the auxiliary detection sources 40, 42, 44 may be omitted, and the software of the traction control system 10 may control the RF device 26 to switch between the first mode and the second mode. In this way, time of flight for distance detection may be employed simultaneously with friction estimation using the common RF device 26 .

[0044] Reference now Figure 2 , shows an example of an RF transmission signal 18 and a reflected RF signal 24 during movement of the vehicle 12. In this example, the RF device 26 is an RF transceiver 46 that incorporates both the transmission properties (via the RF transmitter 20) and the reception properties (via the RF receiver 22) of the RF signal. It is contemplated that in other examples, the RF device 26 includes an RF receiver 22 that is separate from the transmission device (e.g., in another housing or packaging). In the example shown, the vehicle 12 is moving in a direction of movement 50 from a first position 48 toward a second position 52, and the RF transmission signal 18 is reflected off the support surface 38 (as a reflected RF signal 24). When the vehicle 12 is in the second position 52, the reflected RF signal 24 is received at the RF device 26. It is contemplated that the RF transmission / reception arrangement of the present invention may be applied to conditions where the vehicle 12 is not moving relative to the support surface 38 (e.g., parked). In either case, the difference between the RF transmission signal 18 and the reflected RF signal 24 may be detected by the traction control system 10, and such difference may be related to the friction condition of the support 14.

[0045] Continue to refer Figure 2, the RF transmission signal 18 may pass through the medium 54, which may include air and layers of the support 14. The reflected RF signal 24 may include a difference in phase, power, or any other property of the RF transmission signal 18 based on the density, moisture content, or other characteristics of the support 14. For example, the support 14 may include grass, topsoil, gravel, dirt, or any other element of the support 14 on which the vehicle 12 may move or rest. Such layers of the support 14 may interfere with the RF transmission signal 18, causing the reflected RF signal 24 to have different amplitude or phase properties.

[0046] More specifically refer to Figure 2 , the RF transmission signal 18 may have a wavelength ω that is consistent between the RF transmission signal 18 and the reflected RF signal 24. Therefore, a signal transmitted at a given frequency may be returned at a given frequency. Therefore, changes in the reflected RF signal 24 may be in the form of amplitude changes and phase changes in the RF transmission signal 18. For example, the power of the transmission signal may be greater than the power of the reflected RF signal 24. Examples of power may refer to any electromagnetic property of an RF wave, such as voltage, current, magnetic power, etc. In this example, the first amplitude A of the RF transmission signal 18 is T (For example, the transmission amplitude A T ) may be greater than the second amplitude A of the reflected RF signal 24 R (For example, return amplitude A R ).

[0047] Additionally or alternatively, the reflected RF signal 24 may have a phase difference Φ compared to the RF transmission signal 18, such that the reflected RF signal 24 is out of phase with the phase of the RF transmission signal 18. The phase difference Φ may refer to distance, time, degrees, radians, or another quality of phase. For example, in the form of a waveform Figure 2 The RF transmission signal 18 has a curvature of sin(t), where t is time. The reflected RF signal 24 may have a waveform of K·sin(t+Φ), where K is a constant proportional to the amplitude (e.g., the reflection coefficient K). In this example, due to the amplitude A of the reflected RF signal 24 R With respect to the amplitude A of the RF transmission signal 18 T is smaller, so K is a fraction less than one.

[0048] Still refer to Figure 2 , the traction control system 10 may detect the difference between the RF transmission signal 18 and the reflected RF signal 24 and relate the difference to the friction condition of the support 14. For example, the method ( Figure 4) can extract or determine the propagation delay and / or reflection coefficient K by detecting the difference in amplitude and the phase difference Φ. The principles of soil mechanics can then be used to determine soil compactness and / or surface friction. Thus, the traction control system 10 can optimize or enhance on-road and off-road motion control of the vehicle 12.

[0049] It is contemplated that, although shown as separate signals (e.g., RF transmission signal 18 and reflected RF signal 24), in the alternative, a combined signal that is a summation of the RF transmission signal 18 and the reflected RF signal 24 may be processed by the traction control system 10. For example, by operating as an antenna, the RF device 26 may transmit the summation signal to the RF processing controller 56 ( Figure 4 ), the RF processing controller decompresses or extracts the reflected RF signal 24 into isolated parts and compares the extracted signal with the RF transmission signal 18. For example, the RF device 26 can be controlled to transmit the RF transmission signal 18 with a specific amplitude, frequency and phase, and the detected signal can be a combined signal of both the transmission component and the reflected component. Due to the cumulative effect of the two signals, the received signal strength can increase or decrease.

[0050] Reference now FIG. 3A to FIG. 3D , various examples of supports 14 on which the vehicle 12 may rest or move show variations in the reflected RF signal 24 based on the moisture condition and compactness of the supports 14. In general, the return amplitude and phase difference Φ of the reflected RF signal 24 may be detected by the traction control system 10 and correlated to friction conditions. For example, the traction control system 10 may correlate a larger phase difference Φ to a high moisture content of the support 14 and a reduced power level (e.g., a return amplitude A) of the reflected RF signal 24 to a reduced power level (e.g., a return amplitude A) of the reflected RF signal 24. R ) is associated with high compactness. This association can be determined by the RF processing controller 56 ( Figure 4 ) is executed, the RF processing controller compares the properties of the reflected RF signal 24 with predefined values ​​and threshold data (e.g., threshold phase shift value, threshold amplitude shift value) to determine the characteristics of the support 14 and / or the signal. The characteristics include the reflection coefficient K of the support 14, the propagation delay of the RF communication, the density of the support 14 (e.g., the compactness of the soil), the moisture content of the support 14 (e.g., the moisture content of the soil), the shear modulus of the support 14 (e.g., the shear modulus of the soil), or any other characteristics that may affect the output generated by the traction control system 10.

[0051] For example, Figure 3A and Figure 3B Each depicts an example in which the support 14 includes a relatively high moisture content (e.g., wet soil and mud). The reduced amplitude of the reflected RF signal 24 can be associated with a support 14 having a high reflection coefficient K (e.g., asphalt with puddles ( Figure 3C) and dry, compacted ground ( Figure 3D Other conditions of support 14 may cause phase and / or amplitude differences in reflected RF signal 24 similar to the example shown. For example, icy conditions, slippery conditions, sandy conditions, or any other condition of support 14 may be associated with phase and amplitude differences in reflected RF signal 24.

[0052] In general, given soil moisture and compactness estimates, terrain properties (e.g., shear strength, internal friction angle) may be further estimated based on the propagation delay and / or phase difference Φ. For example, for sandy soils, the volumetric soil moisture content may be between 15% and 25%, for loam, between 35% and 45%, and for clay soils, between 45% and 55%. Based on predefined shear strengths and internal friction angles associated with the soil type, the motion profile and / or forces applied by the wheels 32 to the support 14 may be adjusted. The load on the support 14 (e.g., the weight of the vehicle 12 and any objects in the vehicle 12) may be used to further characterize the response of the traction control system 10. For example, the traction control system 10 may use data from one or more weight sensors 62 ( Figure 4 ) to further refine adjustments determined by the traction control system 10 to limit "spinning wheels" or other events with limited traction between the tire 34 and the support 14. In this way, the calculated soil mechanics and / or predefined or estimated vehicle parameters allow the traction control system 10 to model the soil's sinkage, thrust, resistance to motion, slip, etc., and estimate the torque required to pass through the soil, the steering angle of the wheel 32, and / or any other parameter that can control the friction between the tire 34 and the support 14.

[0053] Specific reference Figure 3A, the support 14 includes grass terrain 64 having several soil layers 66. The soil layers 66 have a relatively high level of moisture, as indicated by water droplets 68 within the soil layers 66. Therefore, the grass terrain 64 has a wet, compressible driving surface that has a relatively low compaction. Therefore, due to the high conductivity and low dielectric constant of the soil, the RF transmission signal 18 is reflected with less power, and a relatively large phase difference Φ also occurs between the RF transmission signal 18 and the reflected RF signal 24. The traction control system 10 may associate the reduced amplitude and significant phase shift with a longer propagation delay (e.g., the time period for the signal to return to the RF device 26). Based on the propagation delay, the traction control system 10 may estimate the soil compaction and / or contact moisture content, and may classify the support surface 38 (e.g., in this case, as a wet, compressible surface). Using this classification, the traction control system 10 may control the wheels 32 with more or less torque, or may provide any other output to adjust the traction between the tires 34 and the support 14 (e.g., steering angle, brakes, etc.).

[0054] In another example, and if Figure 3B As shown, the support 14 is a muddy composite 70 with small patches of grass 72 and a relatively high compaction. In such an example, the amplitude A of the reflected RF signal 24 is R May have an amplitude A similar to the RF transmission signal 18 T , and there is also a significant phase difference Φ between the RF transmission signal 18 and the reflected RF signal 24. Therefore, the traction control system 10 can determine a larger propagation delay, and the traction control system 10 can estimate the reflection coefficient K of the support 14 based on the limited amplitude change of the reflected RF signal 24.

[0055] Specific reference Figure 3C , the traction control system 10 scans the hardened road 74. For example, concrete, asphalt, compacted gravel, etc. may be the support 14. In this example, the traction control system 10 detects a relatively high reflection coefficient K due to the puddle 76. In contrast, the area around the puddle (dry hardened road 74) may result in a low reflection coefficient K due to the conductivity and / or density of the hardened road 74. Therefore, the traction control system 10 can detect the difference in the signals 18, 24 as the vehicle 12 moves along the support surface 38 to detect puddles or other water or ice conditions on the road, and control the torque on the wheels 32 in response to such detection.

[0056] Specific reference Figure 3D , dry cracked soil 78 is used as the support 14 monitored by the RF device 26. In this example, due to the conductivity of the soil 78 (e.g., low moisture content), the amplitude A of the reflected RF signal 24 is RSimilar to the amplitude A of the RF transmission signal 18 T . Therefore, traction control system 10 may determine that reflection coefficient K is relatively high. Due to the compactness of dry dirt 78 in this example, reflected RF signal 24 may take longer to pass through dirt 78, resulting in phase difference Φ. Therefore, traction control system 10 may classify the surface as dry ground and determine any adjustments to the forces applied by wheel 32 to limit slip and maintain traction between tire 34 and support 14.

[0057] Reference now Figure 4 , the traction control system 10 includes a control circuit 80 configured to estimate a moisture condition of the support 14 based on the reflected RF signal 24, determine a friction level between the tire 34 and the support 14 based on the moisture condition, and transmit an output to adjust the rotation of at least one of the tires 32 in response to the friction level. The control circuit 80 may include one or more controllers 56, 58, 60, and illustratively include an RF processing controller 56 and a vehicle motion controller 58. Each of the controllers 56, 58, 60 may include one or more processors configured to execute instructions stored in a memory of the controller 56, 58, 60. When the instructions are executed by a given processor, each of the controllers 56, 58, 60 is configured to transmit data related to traction control of the vehicle 12, including writing to or reading from the memory. For example, the RF processing controller 56 may include a phase analyzer module 82 or an RF phasing module configured to process the reflected RF signal 24 from the support 14 detected by the RF device 26. The phase analyzer module 82 may determine the propagation delay and / or the reflection coefficient K based on the phase analysis. It is contemplated that the phase analyzer module 82 may also detect the power level of the signal (eg, the amplitude A of the reflected RF signal 24). R ), and the amplitude A of the reflected RF signal 24 R One or both of the and phase difference Φ are compared with the RF transmission signal 18 to determine the propagation delay and / or the reflection coefficient K.

[0058] The RF processing controller 56 includes a friction estimator unit 84 configured to relate the propagation delay and / or the reflection coefficient K to the surface friction of the support 14. For example, the friction estimator unit 84 may estimate a low level or a high level of friction between the tire 34 and the support 14 based on predefined properties of the tire 34 and detected properties of the support 14. The friction condition may then be transmitted to the vehicle motion controller 58 to allow the vehicle motion controller 58 to adjust at least one parameter of one or more vehicle systems. For example, the vehicle motion controller 58 may control the force applied by the wheel 32, which may be controlled using a chassis control unit 86, a battery control unit 88, a tire pressure control unit 90, a powertrain control unit 92, a steering system 94 of the vehicle 12, and / or a drive motor control unit 96. By controlling one or more vehicle systems, the vehicle motion controller 58 may optimize the force applied by the tire 34 to the support 14 to drive the vehicle 12 in the direction of motion 50. Such processing may also include feedback having the status of brakes, current or another electrical property, steering angle of at least one wheel 32, pressure of tire 34, engine torque, and / or motor torque applied to wheel 32. Thus, in addition to having a proactive element of traction control system 10, feedback from vehicle systems may also refine actions taken by vehicle motion controller 58, such that feedback and signals transmitted to vehicle systems may be provided by tire force optimization unit 97 of vehicle motion controller 58. In this manner, tire 34 force optimization unit may enhance movement of vehicle 12 at a desired speed or and / or desired direction, as previously described.

[0059] Still refer to Figure 4, the traction control system 10 may also include an external monitoring controller 60 in communication with the RF processing controller 56. The external monitoring controller 60 may operate in conjunction with any combination of auxiliary detection sources 40, 42, 44 (such as cameras 40, radars 42, and / or lidars 44) that are operable to detect the distance between the RF device 26 of the vehicle 12 and the support 14. For example, if the RF device 26 has a field of view covering the support 14 5 meters (16.4 feet) in front of the vehicle 12 as the vehicle 12 moves forward, the distance to the support 14 may be based on the terrain toward which the vehicle 12 is moving. For example, if the vehicle 12 is going uphill, the RF device 26 may scan the support 14 at a distance of less than 5 meters due to the RF transmission signal 18 reflecting off the hill. In such examples, the external monitoring controller 60 may more accurately estimate the distance between the RF device 26 and the support 14, and more specifically, the area of ​​the support 14 scanned by the RF device 26. Thus, the auxiliary detection sources 40, 42, 44 connected to the external monitoring controller 60 may capture image data (from the camera 40), distance data (from the radar 42), and / or depth information brackets (from the lidar 44). The distance information may be transmitted to the RF processing controller 56 to allow the RF processing controller 56 to check the propagation delay and reflection coefficient K. For example, the phase analyzer module 82 may operate based on a predefined distance being measured, and when such a predefined distance is inaccurate, the predefined distance may be assigned to the distance estimated by the external monitoring controller 60. In this way, the propagation delay and reflection coefficient K detected by the phase analyzer unit 82 may be more accurately estimated.

[0060] The control circuit 80 can use the flight time of the RF communication to determine the distance from the vehicle 12 to the support 14. The control circuit 80 can be configured to determine a target delay for the RF communication based on the distance and compare the target delay to the propagation delay to estimate the humidity conditions. For example, based on the average distance from the vehicle 12 to the support 14, there may be an expected delay for the RF communication.

[0061] Still refer to Figure 4 , one or more weight sensors 62 can detect the load on the support 14 and transmit the load information to the vehicle motion controller 58. Based on the load information, the vehicle motion controller 58 can be configured to drive the wheels 32 with higher or lower torque, jerk, speed, acceleration, or any other motion profile attribute. Thus, the traction control system 10 can provide a response that uses the prediction of friction conditions in conjunction with other feedback, including the weight of the vehicle 12.

[0062] For example, the control circuit 80 of the traction control system 10 may use the friction conditions estimated by the RF processing controller 56 to control the forces, such as torque, applied to the tires 34. Thus, the acceleration, speed, jerk, or any other motion control property used to drive the tires 34 may be adjusted by the vehicle motion controller 58 to enhance the movement of the vehicle 12. In one example, the vehicle 12 is parked on a wet surface with a high moisture content. Based on the classification of the surface as wet by the RF processing controller 56, the vehicle motion controller 58 may drive one or more of the tires 34 at a slower RPM than the RPM actively requested or indicated by the user of the vehicle 12. For example, if the user depresses the accelerator pedal to drive the wheels 32 at a high RPM, the traction control system 10 may adjust the desired RPM to a target RPM that is lower than the desired RPM to move the vehicle 12 forward. Thus, the adjustment transmitted by the control circuit 80 may be determined based on the classification of the friction conditions of the support 14.

[0063] In another example, the vehicle 12 is moving in the direction of motion 50, and the RF device 26 detects a slippery condition (e.g., standing water, rain accumulation, icy conditions, etc.) along the intended route of the vehicle 12 (e.g., on the road) based on the characteristics of the reflected RF signal 24. In response to detecting the slippery condition, the traction control system 10 may transmit instructions to adjust the operation of the vehicle motion controller 58. The response of the vehicle motion controller 58 may be to adjust the driving of the wheels 32, the braking of the braking system, the power distribution of the battery control unit 88, or any other parameter that may adjust the friction or force between one or more of the tires 34 relative to the support 14. In this way, the traction control system 10 can proactively limit sudden changes in traction.

[0064] Reference now Figure 5 , an exemplary process 98 performed by the traction control system 10 includes transmitting the RF transmission signal 18 toward the support 14 at step S10. For example, the RF processing controller 56 may communicate with the RF transmitter 20 to transmit the RF transmission signal 18 at a certain frequency and amplitude at an initial phase. At step S12, the RF processor receives the reflected RF signal 24, which includes at least one of a phase with a phase difference Φ (e.g., a phase delay) and an adjusted amplitude (e.g., an increased amplitude or a decreased amplitude). For example, at step S14, the traction control system 10 may determine a power difference, and at step S16, the traction control system 10 may determine the phase difference Φ. Applying the process 98 to Figure 4 In the example shown, the RF process controller 56 may perform steps S10 to S16 .

[0065] At step S18, the RF processing controller 56 may classify the support object condition based on the difference between the transmitted signal and the reflected RF signal 24. At step S20, the traction control system 10 estimates the friction condition based on the classification of the support object 14 (e.g., the condition of the support object 14). For example, if the support object condition is classified as icy, muddy, wet, sandy, or any other support object condition, the RF processing controller 56 may associate such classification with the surface friction estimate.

[0066] As previously described, friction conditions may include surface texture, such as soil texture, shear strength, shear modulus, etc. The traction control system 10 may determine the friction conditions by measuring the difference between the RF transmission signal 18 and the reflected RF signal 24, thereby classifying the difference into a type of terrain condition (e.g., soil, soil moisture, soil compaction, hard road, gravel, ice, water, etc.), and determining the frictional qualities of a given terrain in the exterior region. For example, wet dirt 78 may be more likely to cause the vehicle 12 to get stuck than dry dirt 78.

[0067] Still refer to Figure 5 , at step S22, the movement of the wheels 32 may be adjusted to move the vehicle 12 and the desired direction of movement 50. For example, the RF processing controller 56 may transmit the friction condition to the vehicle motion controller 58. In response, the vehicle motion controller 58 may transmit instructions to one or more of the vehicle systems previously described. For example, the vehicle motion controller 58 may adjust the drive of the motor controller for one or more of the wheels 32 of the vehicle 12 to adjust the torque or force applied to the support 14. In some examples, step 22 includes using any feature of the traction control system 10 to adjust the force between the tire 34 and the support 14.

[0068] Generally, the traction control system 10 can provide enhancements for off-road vehicle applications, such as when the vehicle 12 faces unknown terrain or surface conditions modified relative to stored data of the terrain. In addition, the present traction control system 10 can enhance the operation of a multi-mode traction control to adjust operation on multiple terrains.

[0069] It should be understood that changes and modifications may be made to the foregoing constructions without departing from the concepts of the present disclosure, and it should be further understood that such concepts are intended to be encompassed by the appended claims unless the claims expressly state otherwise by their language.

[0070] According to the present invention, a vehicle is provided, the vehicle having: at least one wheel, the at least one wheel driving a tire to move the vehicle along a support; a radio frequency (RF) transceiver, the RF transceiver transmitting an RF signal toward the support and measuring a reflected signal; a drive unit, the drive unit driving the rotation of the at least one wheel; a control circuit, the control circuit communicating with the RF transceiver and the drive unit, the control circuit being configured to: estimate a moisture condition of the support based on the reflected signal; determine a friction level between the tire and the support based on the moisture condition; and transmit an output in response to the friction level to adjust a force between the tire and the support.

[0071] According to an embodiment, the control circuit is configured to: control the RF transceiver to output the RF signal with a first phase; compare a second phase of the reflected signal with the first phase to detect a phase difference; and estimate the humidity condition of the support based on the phase difference.

[0072] According to an embodiment, the control circuit is configured to determine a propagation delay based on the phase difference.

[0073] According to an embodiment, the support is soil and the control circuit is configured to estimate a soil compaction level based on the propagation delay.

[0074] According to an embodiment, the present invention is also characterized by: a time-of-flight device, which is configured to detect the distance from the vehicle to the support along the path of the RF signal, wherein the control circuit is also configured to: determine a target delay of the RF signal based on the distance; and compare the target delay with the propagation delay to estimate the humidity condition.

[0075] According to an embodiment, the control circuit is configured to: detect an amplitude difference between the RF signal and the reflected signal; and determine a reflection coefficient of the support based on the amplitude difference.

[0076] According to an embodiment, the support is soil and the control circuit is configured to estimate the soil compaction level based on the reflection coefficient.

[0077] According to an embodiment, the control circuit is configured to determine a shear modulus of the support based on the phase difference.

[0078] According to an embodiment, the control circuit is configured to determine a friction angle based on the phase difference.

[0079] According to an embodiment, the invention also features a braking system configured to selectively limit rotation of the tire in response to the wetness condition.

[0080] According to an embodiment, the control circuit includes: a motion control module having multiple modes configured to drive the at least one wheel at multiple speeds; and an RF phasing module configured to detect a phase difference between the RF signal and the reflected signal to estimate the humidity condition.

[0081] According to an embodiment, the RF transceiver includes: an RF transmitter that transmits the RF signal toward the support; and an RF receiver that measures the reflected signal reflected by the support.

[0082] According to the present invention, a vehicle is provided, the vehicle having: at least one wheel, the at least one wheel driving a tire to move the vehicle along a support; a radio frequency (RF) transceiver, the RF transceiver transmitting an RF signal toward the support and measuring a reflected signal; a drive unit, the drive unit driving the rotation of the at least one wheel; a control circuit, the control circuit communicating with the RF transceiver and the drive unit, the control circuit being configured to: control the RF transceiver to output the RF signal at a first phase; compare a second phase of the reflected signal with the first phase to detect a phase difference; estimate the humidity condition of the support based on the phase difference; determine a friction level between the tire and the support based on the humidity condition; and transmit an output in response to the friction level to adjust the force between the tire and the support.

[0083] According to an embodiment, the control circuit is configured to: detect an amplitude difference between the RF signal and the reflected signal; and determine a reflection coefficient of the support based on the amplitude difference.

[0084] According to an embodiment, the control circuit is configured to determine a propagation delay based on the phase difference.

[0085] According to an embodiment, the present invention is also characterized by: a time-of-flight device, which is configured to detect the distance from the vehicle to the support along the path of the RF signal, wherein the control circuit is also configured to: determine a target delay of the RF signal based on the distance; and compare the target delay with the propagation delay to estimate the humidity condition.

[0086] According to an embodiment, the invention also features a braking system configured to selectively limit rotation of the tire in response to the friction level.

[0087] According to an embodiment, the control circuit includes: a motion control module having multiple modes configured to drive the at least one wheel at multiple speeds; and an RF phasing module configured to detect a phase difference between the RF signal and the reflected signal to estimate the humidity condition.

[0088] According to the present invention, a vehicle is provided, the vehicle having: at least one wheel, the at least one wheel driving a tire to move the vehicle along soil; a radio frequency (RF) transmitter, the RF transmitter transmitting an RF signal toward the soil; an RF receiver, the RF receiver receiving a reflected signal reflected by the soil; a drive unit, the drive unit driving the rotation of the at least one wheel; a control circuit, the control circuit communicating with the RF transmitter, the RF receiver and the drive unit, the control circuit being configured to: control the RF transmitter to output the RF signal at a first phase; compare a second phase of the reflected signal with the first phase to detect a phase difference; estimate the moisture condition of the soil based on the phase difference; determine a friction level between the tire and the support based on the moisture condition; and transmit an output in response to the friction level to adjust the force between the tire and the support.

[0089] According to an embodiment, the invention also features a braking system configured to selectively limit rotation of the tire in response to the friction level.

Claims

1. A vehicle, comprising: at least one wheel, the at least one wheel driving a tire to move the vehicle along a support; a radio frequency (RF) transceiver that transmits an RF signal toward the support and measures a reflected signal; a drive unit, the drive unit driving the rotation of the at least one wheel; a control circuit, the control circuit being in communication with the RF transceiver and the driving unit, the control circuit being configured to: estimating a humidity condition of the support based on the reflected signal; determining a friction level between the tire and the support based on the moisture conditions; as well as An output is transmitted in response to the friction level to adjust a force between the tire and the support.

2. The vehicle of claim 1, wherein the control circuit is configured to: controlling the RF transceiver to output the RF signal with a first phase; comparing a second phase of the reflected signal with the first phase to detect a phase difference; and The humidity condition of the support is estimated based on the phase difference.

3. The vehicle of claim 2, wherein the control circuit is configured to: A propagation delay is determined based on the phase difference.

4. The vehicle of claim 3, wherein the support is soil and the control circuit is configured to estimate a soil compaction level based on the propagation delay.

5. The vehicle of claim 3, further comprising: a time-of-flight device configured to detect a distance from the vehicle to the support object along a path of the RF signal, wherein the control circuit is further configured to: determining a target delay for the RF signal based on the distance; and The target delay is compared to the propagation delay to estimate the humidity condition.

6. The vehicle of claim 2, wherein the control circuit is configured to: detecting an amplitude difference between the RF signal and the reflected signal; and A reflection coefficient of the support is determined based on the amplitude difference.

7. The vehicle of claim 6, wherein the support is soil and the control circuit is configured to estimate a soil compaction level based on the reflection coefficient.

8. The vehicle of any one of claims 2 to 7, wherein the control circuit is configured to: A shear modulus of the support is determined based on the phase difference.

9. The vehicle of any one of claims 2 to 8, wherein the control circuit is configured to: A friction angle of the support is determined based on the phase difference.

10. The vehicle of claims 1 to 9, further comprising: A braking system is configured to selectively restrict rotation of the tire in response to the wetness condition.

11. The vehicle of any one of claims 1 to 10, wherein the control circuit comprises: a motion control module having a plurality of modes configured to drive the at least one wheel at a plurality of speeds; as well as An RF phasing module is configured to detect a phase difference between the RF signal and the reflected signal to estimate the humidity condition.

12. The vehicle of any one of claims 1 to 11, wherein the RF transceiver comprises: an RF transmitter that transmits the RF signal toward the support; and an RF receiver that measures the reflected signal reflected by the support.

Images