System and method for estimating vehicle wheel speed

Abstract

A system and method for estimating a wheel speed of a vehicle is provided. The system includes a wheel speed sensor that detects a rotation speed of a wheel of the vehicle and an engine speed sensor that detects a speed of a driving engine. A controller receives a signal of the wheel speed sensor, a signal of the engine speed sensor, and information about a gear indicating a current gear state of a transmission, and estimates the wheel speed including information on a direction of wheel rotation.

Description

Technical Field

[0001] The present invention generally relates to systems and methods for estimating vehicle wheel speed, and more particularly, to systems and methods for estimating vehicle wheel speed that overcome problems of typical wheel speed sensors, such as reduced resolution in low speed ranges and lack of information about the direction of rotation. Background Art

[0002] Generally, a vehicle includes various sensors configured to detect various pieces of information required to control and operate various related devices of the vehicle or to provide or display information. Necessary information includes information indicating a driving state, a vehicle state, a state of an onboard device, etc., and environmental information indicating temperature, humidity level, luminous intensity inside and outside the vehicle, etc.

[0003] In addition, the vehicle includes various devices that are controlled and operated based on various information collected using sensors. These devices are set and used to provide basic driving performance of the vehicle, ensure vehicle safety and driving reliability, protect drivers and passengers, reduce shock and noise, and improve convenience and ride comfort.

[0004] For example, a vehicle includes a wheel speed sensor configured to detect the rotational speed of a wheel of the vehicle, i.e., the wheel speed. A typical system using the signal of the wheel speed sensor may be an anti-lock braking system (ABS) that prevents wheels from locking or sliding when braking the vehicle, a traction control system (TCS) that prevents wheels from sliding by operating the engine or brakes during sudden departure or sudden acceleration of the vehicle, and the like.

[0005] In addition, such a system may be an engine speed sensor configured to detect an engine speed, i.e., the speed of a driving source of an internal combustion engine (ICE) vehicle; a rotary transformer configured to detect an engine speed, i.e., the speed of a driving source of an environmentally friendly vehicle; a longitudinal acceleration sensor configured to detect a longitudinal acceleration of a vehicle, etc. The vehicle-mounted system using the signals of the rotary transformer, the wheel speed sensor, the longitudinal acceleration sensor, etc. may be a misfire prevention control system for reducing vibration and shock, a hill start assist control (HAC) system for preventing a vehicle from rolling back from a slope, etc.

[0006] The wheel speed sensor in the vehicle sensor may include a speed pulse wheel, a permanent magnet, a coil (or a Hall effect element), etc. A plurality of teeth are provided on the outer peripheral surface of the speed pulse wheel to cause a change in the magnetic field of the permanent magnet when the speed pulse wheel rotates. The rotation speed (wheel speed) of the wheel can be determined by converting the change in the magnetic field into a pulse electrical signal and detecting the electrical signal, and this is information about the speed in which the direction information of the unknown wheel rotation is as described below. However, the use of the wheel speed sensor has the following problems.

[0007] Wheel speed is important information for vehicle control. In the field of chassis control, such as anti-lock braking system (ABS), traction control system (TCS), and hill start assist control (HAC) system, the vehicle is usually operated based on wheel speed information detected by a wheel speed sensor (excluding information about the rotation direction in the forward / reverse direction) or the vehicle speed calculated based on the wheel speed information.

[0008] In addition, wheel speed has a basic function in the field of control related to the drive system, such as transmission control, torque command generation, or four-wheel drive control. The resolution and accuracy of wheel speed information must have a predetermined level or higher so that the control process based on the wheel speed can be optimally performed as expected. In particular, during the control process of the vehicle, fast and accurate calculation and judgment in response to instantaneously changing real-time situations are required. In this regard, when obtaining information for calculation and judgment, it is important to obtain sensor information that accurately indicates the current real-time situation and information that is quickly updated.

[0009] However, the resolution of the wheel speed (or angular velocity) measured by the sensor is proportional to the number of pulses (i.e., the number of times the encoder slit moves). Since a smaller number of pulses can be better identified at relatively low speeds than at relatively high speeds, the problem of reduced resolution occurs in the low speed range.

[0010] Since the wheel speed sensor detects information by reading the number of pulse signals generated by the rotation of the speed pulse wheel, a reading period of a predetermined level or higher is required within a predetermined time. In particular, in a low speed range where the speed must be read by identifying a small number of pulse signals, a long period of time is required to generate a subsequent pulse after a previous pulse. Therefore, there is no pulse signal during such a reading period. Therefore, in some cases where the wheel rotates at a low speed without stopping, a wheel speed signal indicating the wheel speed may not be output, and the wheel speed information may not be obtained.

[0011] The wheel speed sensor currently used in vehicles is an incremental encoder sensor. According to the characteristics of the encoder, the wheel speed is calculated based on the number of pulses recognized per unit time (i.e., the number of times the encoder slit moves). However, this sensor does not output a wheel speed signal in a low-speed state of the vehicle (such as in crawling). Therefore, although the wheel is obviously rotating even at an extremely low speed, the wheel speed information may indicate zero (0). In addition, when the vehicle is traveling at a low speed when crawling, the update cycle of the wheel speed information is slow. In particular, in the initial stage of crawling, that is, the extremely slow driving state when the vehicle starts from a stopped position, the accurate speed cannot be identified because no wheel speed signal is output.

[0012] Since the wheel speed cannot be identified without reading the number of pulses within a predetermined time, the update of information is necessarily slow. Even when an instantaneous change in wheel speed occurs, the current wheel speed cannot be accurately identified using the sensor. Therefore, in the above-mentioned control process required to respond to instantaneous real-time conditions, there may be problems when only using sensor information. For example, even when executing a known control process (e.g., a misfire prevention control process) to reduce noise and vibration caused by torque and backlash by detecting the torque state of the vehicle drive system, wheel speed information in an extremely slow state may not be obtained or used.

[0013] As described above, although other sensors can be used for reading and control for a relatively short period of time, the wheel speed sensor may have the problem of slow update of the read information compared to other sensors. Therefore, in the wheel speed sensor, accurate wheel speed information may not be reflected in the control in real time. In addition, since the signal of the incremental encoder does not include the classification of the number of pulses according to the direction of wheel rotation and the information about the direction of wheel rotation, the directionality of the wheel rotation is not determined by the signal. In other words, although the direction of wheel rotation when the gear is the drive (D) gear is opposite to the direction of wheel rotation when the gear is the reverse gear (R), it is impossible to identify the direction of wheel rotation using only the signal of the encoder wheel speed sensor.

[0014] For example, in a case where fire control must be performed while the vehicle is traveling at an extremely low speed, when the driver forcibly changes the gear from the D gear to the R gear, the precise wheel state must be detected instantaneously during the shift from the D gear (e.g., the first gear) to the R gear. However, the wheel rotation direction cannot be identified using the wheel speed sensor. Since the signal output by the typical wheel speed sensor does not include information about the wheel rotation direction, that is, information about the rotation direction, for example, in the driving direction (forward direction) or in the reverse direction (reverse direction), it may not be possible to determine whether the wheel is rotating in the driving direction (forward direction) or in the reverse direction (reverse direction) based only on the signal of the wheel speed sensor.

[0015] The foregoing content is only intended to help understand the background of the present invention and does not mean that the present invention belongs to the scope of the relevant technology known to those skilled in the art. Summary of the invention

[0016] Thus, the present invention provides a system and method for estimating the wheel speed of a vehicle that overcomes the problems of typical wheel speed sensors, such as reduced resolution in the low speed range and lack of information about the direction of rotation. In particular, the present invention provides a system and method for estimating the wheel speed of a vehicle, wherein the directionality of wheel rotation can be more accurately determined based on the signal of an engine speed sensor, and the information about the direction of wheel rotation can be used to estimate the wheel speed.

[0017] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, as a system including a driving engine and a transmission, and using the transmission to perform reverse motion, a system for estimating the wheel speed of a vehicle may include: a wheel speed sensor configured to detect the rotational speed of the wheel; an engine speed sensor configured to detect the speed of the driving engine; and a controller configured to receive a signal from the wheel speed sensor, a signal from the engine speed sensor, and information about the gear indicating the current gear state of the transmission, and estimate the wheel speed including the directionality of wheel rotation.

[0018] Herein, the controller may include a direction determination module configured to obtain direction information indicating the direction of wheel rotation from engine speed information obtained according to a signal of an engine speed sensor and gear information. In addition, the controller may be configured to estimate the wheel speed including the directionality of wheel rotation using the real-time direction information obtained by the direction determination module and the signal of the wheel speed sensor.

[0019] According to another aspect of the present invention, as a method including driving an engine and a transmission, and using the transmission to perform reverse motion, a method for estimating the wheel speed of a vehicle may include: receiving, by a controller, a signal from a wheel speed sensor, a signal from an engine speed sensor, and information about a gear indicating a current gear state of the transmission; obtaining, by the controller, engine speed information obtained by a direction determination module from the signal from the engine speed sensor and direction information indicating a direction of wheel rotation from the information about the gear; and, using real-time direction information obtained from the signal from the wheel speed sensor and the direction determination module, estimating, by the controller, the wheel speed including the directionality of wheel rotation.

[0020] As described above, the wheel speed estimation system and method according to the present invention can obtain more accurate wheel speed information within a relatively short update period. Even when the vehicle is traveling at an extremely low speed during creeping, a more accurate wheel speed value reflecting the actual situation of the wheel can be obtained as real-time information. In addition, by the system and method for estimating the wheel speed of a vehicle according to the present invention, the directionality of wheel rotation can be determined more accurately based on the signal of the engine speed sensor, and the wheel speed can be estimated using information about the direction in which the wheel is rotating.

[0021] In particular, in the wheel speed estimation system and method according to the present invention, a wheel speed value including real-time rotation direction information can be obtained during low-speed driving, for example, from a situation in which the driver inputs a reverse driving input (i.e., performs an R-range manipulation). Therefore, problems that occur when only a wheel speed sensor is used, such as reduced resolution in a low-speed range and no information on the rotation direction, can be overcome. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0023] Figure 1 is a block diagram showing a configuration of a system for estimating wheel speed according to an exemplary embodiment of the present invention;

[0024] Figure 2 is a block diagram specifically showing an internal configuration of a controller of a system for estimating wheel speed according to an exemplary embodiment of the present invention;

[0025] Figure 3 is a diagram illustrating engine speed, wheel speed information, and gear information used in a wheel speed estimating process according to an exemplary embodiment of the present invention, and a final estimated wheel speed. DETAILED DESCRIPTION

[0026] It should be understood that the terms "vehicle" or "vehicular" or other similar terms used herein include motor vehicles, generally passenger cars including sport utility vehicles (SUVs), buses, trucks, various commercial vehicles, watercraft including various ships, aircraft, etc., and include hybrid vehicles, electric vehicles, internal combustion engines, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other alternative fuel vehicles (e.g., fuels derived from non-petroleum resources).

[0027] Although the exemplary embodiments are described as using multiple units to perform the exemplary processes, it should be understood that the exemplary processes can also be performed by one or more modules. In addition, it should be understood that the term controller / control unit refers to a hardware device including a memory and a processor. The memory is configured to store the modules, and the processor is specifically configured to execute the modules to perform one or more processes described further below.

[0028] In addition, the control logic of the present invention may be embodied as a non-transitory computer readable medium on a computer readable medium containing executable program instructions executed by a processor, a controller / control unit, etc. Examples of computer readable media include, but are not limited to, ROM, RAM, compact disk (CD)-ROM, magnetic tape, floppy disk, flash drive, smart card, and optical data storage device. The computer readable recording medium may also be distributed in a network coupled computer system so that the computer readable medium is stored and executed in a distributed manner, such as by a telematics server or a controller area network (CAN).

[0029] The terms used herein are only used for the purpose of describing specific embodiments and are not intended to limit the present invention. As used herein, the singular forms "a", "an", and "the" are intended to also include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "comprise" and / or "comprising" when used in this specification specify the presence of the features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the relevant listed items.

[0030] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention relates can easily put the present invention into practice. However, the present invention is not limited to the exemplary embodiments described herein and may be embodied in other forms.

[0031] The present invention relates to a system and method capable of obtaining information about wheel speed using a signal from an engine speed sensor, the information including information about a driving direction and a reverse rotation direction (i.e., information about the wheel rotation direction). As described above, since real-time information has a relatively short update cycle, it may be difficult to obtain an accurate value of the wheel speed of a vehicle using only a commonly used wheel speed sensor. In particular, when the vehicle is traveling at a low speed when crawling, it may be difficult to measure the wheel speed using the wheel speed sensor. Therefore, as a solution to this problem, information about the conversion of the vehicle's driving source speed into the wheel speed based on information about the transmission ratio of the transmission (hereinafter, referred to as "wheel speed information") may be used.

[0032] As described above, using only the known wheel speed sensor, it may not be possible to obtain wheel speed information including information about the rotation direction of the wheel (hereinafter referred to as "direction information of wheel rotation"). Therefore, a drive source speed sensor configured to detect the drive source speed is additionally used in the present invention. In particular, the drive source speed of the vehicle may be the speed of the engine or the engine connected to the input side of the transmission, that is, the speed of the engine of an internal combustion engine (ICE) vehicle or the speed of the engine of an environmentally friendly vehicle such as an electric vehicle (EV), a fuel cell vehicle (FCV) or a hybrid electric vehicle (HEV).

[0033] Based on the transmission ratio corresponding to the current gear of the transmission, the driving source speed of the vehicle can be converted and changed into the wheel speed (i.e., the equivalent speed at the wheel). In the present invention, by using information about the transmission ratio of the transmission, i.e., the transmission ratio conversion speed, the speed obtained by converting the driving source speed of the vehicle detected by the driving source speed sensor into the wheel speed can be used to estimate the wheel speed.

[0034] In a typical environmentally friendly vehicle, a resolver (i.e., an engine speed sensor) can be used to measure the speed of the engine (i.e., the vehicle drive source). Using a resolver, real-time information indicating the engine speed and the rotation direction of the engine can be accurately obtained. Therefore, when the speed of the engine measured using a resolver is converted and changed based on the transmission ratio, the wheel speed information (i.e., the transmission ratio conversion speed) can be obtained more accurately.

[0035] Although accurate speed can be measured using a rotary transformer, it may be difficult to measure accurate speed in real time using a wheel speed sensor. Therefore, by converting the engine speed measured by the rotary transformer into a wheel speed based on the gear ratio, the necessary wheel speed (i.e., the gear ratio conversion speed) can be obtained. However, the gear ratio conversion speed cannot be used to detect torque in the drive shaft or backlash in the drive system.

[0036] Described in more detail, the torque in the drive shaft or the backlash in the drive system refers to the torque or backlash between the engine (i.e., the vehicle drive source) and the wheel. The torque or backlash can be detected as the difference between the transmission ratio conversion speeds, that is, the difference between the wheel speed obtained by converting the engine speed based on the transmission ratio and the actual speed of the wheel. However, the actual speed of the wheel cannot be replaced by the transmission ratio conversion speed. In other words, although the torque or backlash must be detected with a magnitude equal to the difference between the transmission ratio conversion speed and the actual wheel speed, the speed difference cannot be obtained because the transmission ratio conversion speed and the actual wheel speed are considered to be the same when the transmission ratio conversion speed is used instead of the actual wheel speed.

[0037] Therefore, in order to detect torque or backlash, a signal indicating the engine speed and a signal indicating the wheel speed must exist separately. Unless the actual wheel speed is obtained separately, not converted from the engine speed, torque at low speed or torque in misfire prevention control, etc. cannot be detected. In particular, torque cannot be detected compared with the engine speed (i.e., the drive source speed) unless real-time wheel speed information indicating the actual wheel speed is accurately obtained regardless of the speed condition (e.g., extremely low speed at the time of creeping).

[0038] Therefore, the present invention provides a system and method, by which the wheel speed under actual conditions can be obtained more accurately, and in particular, wheel speed information that further indicates the direction of wheel rotation can be obtained, because the real-time information has a relatively short update period.

[0039] Figure 1 is a block diagram showing a configuration of a system for estimating wheel speed according to an exemplary embodiment of the present invention, and Figure 2 is a block diagram specifically showing the internal configuration of a controller of a system for estimating wheel speed according to an exemplary embodiment of the present invention. In addition, Figure 3 is a diagram illustrating engine speed, wheel speed information, and gear information used in a wheel speed estimating process according to an exemplary embodiment of the present invention, and a final estimated wheel speed.

[0040] refer to Figure 1 , a system for estimating wheel speeds according to an exemplary embodiment of the present invention may include wheel speed sensors 11 to 14, a driving source speed sensor 15, a longitudinal acceleration sensor 16, and a controller 20. Here, the wheel speed sensors 11 to 14 may be known sensors provided on vehicle wheels to respectively detect wheel speeds of corresponding wheels.

[0041] The wheel speed sensors 11 to 14 may be provided on driving wheels powered by a vehicle driving source (e.g., an engine or a motor), and more specifically, may be wheel speed sensors provided on the front wheels of a front wheel drive (FWD) vehicle or wheel speed sensors provided on the rear wheels of a rear wheel drive (RWD) vehicle. In particular, the wheel speed finally estimated according to the present invention is the rotation speed of the driving wheel estimated using the signal of one of the wheel speed sensors 11 to 14 provided on the corresponding wheel.

[0042] In addition, in a four-wheel drive (FWD) vehicle in which the power of the wheel driving source is supplied to the front wheels and the rear wheels, the wheel speed sensors 11 to 14 may be provided on the front wheels and the rear wheels. The wheel speed finally estimated according to the present invention is equal to the rotation speed of each of the four wheels, and is estimated using the signal of one of the wheel speed sensors 11 to 14 provided on the corresponding wheel.

[0043] Figure 1An exemplary configuration in a four-wheel drive vehicle is shown, in which wheel speed sensors 11 to 14 arranged on the left front wheel FL, the right front wheel FR, the left rear wheel RL, and the right rear wheel RR can be used. Although the final wheel speed is estimated using the signal of one of the wheel speed sensors 11 to 14 arranged on the corresponding wheels according to the present invention, the problems that occur when only the wheel speed sensors 11 to 14 are used can be overcome. In other words, problems such as reduced resolution in the low speed range and lack of information about the rotation direction can be overcome. Therefore, the final wheel speed estimated according to the present invention is an actual wheel speed that more accurately represents the real-time situation than the value detected by the wheel speed sensors 11 to 14, and is real-time information obtained in a shorter update cycle than when only the wheel speed sensors 11 to 14 are used.

[0044] The driving source speed sensor 15 may be configured to detect the rotational speed of the driving source of the vehicle. More specifically, the driving source speed sensor 15 may be configured to more accurately measure the speed of the engine of the driving source of the vehicle as real-time information on the input side of the transmission (in an internal combustion engine vehicle) or more accurately measure the speed of the engine as real-time information on the input side of the transmission (in an environmentally friendly vehicle). The driving source speed sensor 15 in the environmentally friendly vehicle may be a known engine speed sensor, i.e., a rotary transformer, which is configured to output a signal indicating the speed of the engine and the rotation direction of the engine in real time.

[0045] In addition, in a vehicle in which the vehicle driving source is connected to the input side of the transmission, the driving source speed measured by the driving source speed sensor 15 is the speed of the input shaft of the transmission. When the sensor can accurately detect the rotation speed and the rotation direction, the speed of the input shaft of the transmission may be used instead of the driving source speed of the vehicle (e.g., the engine speed) hereinafter.

[0046] In addition, at a position where a hybrid starter and engine (HSG) is connected to the wheels in a power-transmittable manner, the speed of the HSG detected by a separate sensor (i.e., a rotary transformer) may be used instead of the drive source speed of the vehicle. In addition, the longitudinal acceleration sensor 16 may be a known sensor (e.g., an inertial sensor) provided to detect the longitudinal acceleration of the vehicle. The above-mentioned system and method for estimating wheel speed according to the present invention may use the wheel speed sensors 11 to 14, the drive source speed sensor 15, and the longitudinal acceleration sensor 16 as known sensors provided on the vehicle.

[0047] In addition, the controller 20 may be configured to receive measurements of wheel speed, engine speed, and longitudinal acceleration obtained from signals of sensors 11 to 14, and estimate wheel speed based on the measurements. In particular, the controller 20 may include a set of software that is installed and executed to estimate wheel speed based on measurements of the sensors. It is noteworthy that the controller 20 may be specifically programmed to perform the processes described herein. Therefore, the controller 20 may be configured to estimate wheel speed from measurements of the sensors according to processes and methods defined by software algorithms. According to an exemplary embodiment of the present invention, the controller 20 may include an observer module 23 that is configured to estimate wheel speed, as will be described later.

[0048] Describes in more detail the Figure 2 The controller 20 of the exemplary embodiment mentioned in the figure may include a longitudinal acceleration input unit 21, a wheel speed input unit 22 and an observer module 23. First, the longitudinal acceleration input unit 21 may be configured to receive a signal from the longitudinal acceleration sensor 16, and obtain the real-time longitudinal acceleration information of the vehicle from the received signal for use by the observer module 23.

[0049] The longitudinal acceleration input section 21 may be provided on and connected to the input side of the observer module 23 to input real-time longitudinal acceleration information obtained from the signal of the longitudinal acceleration sensor 16 to the observer module 23. Since the signal of the longitudinal acceleration sensor 16 for wheel speed estimation according to the present invention includes a gradient component such as a pitch angle of a vehicle suspension and a road gradient, it may be necessary to obtain information on the signal value of the longitudinal acceleration sensor 16 from which the gradient component is removed by correction, i.e., real-time information indicating a pure longitudinal acceleration of the vehicle.

[0050] Therefore, the longitudinal acceleration input section 21 may be configured to obtain longitudinal acceleration information of the vehicle based on the signal value of the longitudinal acceleration sensor 16. The longitudinal acceleration input section 21 may be configured to obtain longitudinal acceleration information, wherein the signal value is additionally corrected by a preset separate model or logic for gradient or load correction based on additional information (possibly including sensor information) (e.g., information set to be stored in the longitudinal acceleration input section 21, real-time vehicle speed information, and vehicle load information).

[0051] In a typical vehicle, a longitudinal acceleration sensor is used to obtain road slope (or gradient) information. As is well known in the art, there is a method of obtaining the road slope by removing the longitudinal acceleration component of the vehicle from the signal of the longitudinal acceleration sensor, or conversely, obtaining the pure longitudinal acceleration value information of the vehicle by removing the gradient component. As described above, any of a variety of known methods, such as the above-mentioned correction method, can be used, and they can be used to obtain the pure longitudinal acceleration value information of the vehicle according to the present invention, as long as the method can obtain the pure longitudinal acceleration value information of the vehicle from the signal value of the longitudinal acceleration sensor, removing the gradient component therefrom.

[0052] Also as described above, the longitudinal acceleration input section 21 may be configured to obtain longitudinal acceleration information including a pure longitudinal acceleration component of the vehicle, remove a gradient component therefrom, and then output the longitudinal acceleration information to be input to the observer module 23. Furthermore, the wheel speed input section 22 is a component configured to obtain wheel speed information to be used in the observer module 23 from signals of the wheel speed sensors 11 to 14 mounted on the wheels.

[0053] The wheel speed input portion 22 may be provided on and connected to an input side of the observer module 23, so that the wheel speed input portion 22 may input wheel speed information obtained from the signals of the wheel speed sensors 11 to 14 to the observer module 23. According to an exemplary embodiment, the wheel speed information obtained using only the signals of the wheel speed sensors 11 to 14 may be replaced by wheel speed information corrected using a signal of an engine speed sensor (i.e., a resolver) in addition.

[0054] In other words, although the wheel speed input portion 22 may be configured to obtain the wheel speed estimation value to be used as the input of the observer module 23 using only the signal of each of the wheel speed sensors 11 to 14, the wheel speed input portion 22 may also be configured to obtain the wheel speed estimation value corrected using the signal of each wheel speed sensor 11 to 14 and the signal of the engine speed sensor (or resolver) 15. In particular, the wheel speed input portion 22 may be configured to obtain the corrected wheel speed information, which is a value generated by multiplying the wheel speed (excluding the direction information) obtained from the signal of each wheel speed sensor 11 to 14 and the gear ratio conversion speed by weights, respectively, and then summing the obtained products.

[0055] The gear ratio conversion speed is an equivalent wheel speed obtained by converting the engine speed obtained from the signal of the engine speed sensor (or rotary transformer) 15 into the wheel speed based on the gear ratio corresponding to the current gear position of the transmission. In other words, the wheel speed estimation value to be input to the observer module 23 can be determined by a weighted summation method, in which the wheel speed obtained from the signal of each wheel speed sensor 11 to 14 and the gear ratio conversion speed signal finally obtained from the signal of the engine speed sensor 15 are respectively multiplied by predetermined weights and then summed. In particular, the value of the weight can be set so that the sum of the two weights, i.e., the weight multiplied by the wheel speed and the weight multiplied by the gear ratio conversion speed is one (1). The optimal value obtained through the previous test experiment can be used as the weight.

[0056] According to an exemplary embodiment, the weight may vary according to the wheel speed or the gear ratio conversion speed. The weight value corresponding to the wheel speed or the gear ratio conversion speed may be selected and determined for use. The lower the speed (or velocity), the smaller the value of the weight multiplied by the wheel speed measured by the sensors 11 to 14 may be, while the larger the value of the weight multiplied by the gear ratio conversion speed may be.

[0057] Therefore, the portion of the engine speed in the wheel speed estimation value calculated by the weighted sum method (i.e., the portion of the gear ratio conversion speed) is increased in the low speed range, while the portion of the wheel speed measured by the sensors 11 to 14 (i.e., the measured values ​​of the wheel speed sensors) can be increased in the higher speed range where the resolution of the wheel speed sensors 11 to 14 is sufficiently high. In addition, when the wheel speed is used, when no signal is output from the wheel speed sensors 11 to 14 because the vehicle is traveling very slowly, the wheel speed or the weight can be regarded as zero (0). Therefore, the gear ratio conversion speed can be input to the error calculator 25 of the observer module 23, which will be described later, as wheel speed information for calculating the speed error.

[0058] The wheel speed input section 22 may use an absolute value, i.e., a positive value, for both the wheel speed and the gear ratio conversion speed to which the weight is applied. In addition, the observer module 23 may include an acceleration converter 24, an error calculator 25, a feedback control value calculator 26, an adder 27, an integrator 28, and a direction corrector 29. First, the observer module 23 may be configured to require two types of inputs, which are two types of input information about feedforward (FF) and feedback (FB). One of the two types of input information is the longitudinal acceleration information of the vehicle input via the longitudinal acceleration input section 21, and the other of the two types of input information is information about the wheel speed estimation value input via the wheel speed input section.

[0059] In the observer module 23, the acceleration converter 24 may be configured to convert the feedforward related input information (i.e., the real-time longitudinal acceleration information of the vehicle input via the longitudinal acceleration input section 21) into the wheel acceleration based on the tire radius (or rolling radius). According to an exemplary embodiment of the present invention, the real-time longitudinal acceleration of the vehicle may be divided by the tire rolling radius value to be changed into the wheel acceleration. The tire rolling radius value may be a corrected value obtained by correcting a previous tire rolling radius value based on the engine speed information.

[0060] Specifically, the difference between the change speed obtained by changing the previous wheel speed estimated (or observed) by the observer module 23 into the engine speed by integrating the gear ratio information based on the current gear and the actual engine speed measured in real time by the engine speed sensor can be obtained. Then, the correction value can be obtained by correcting the previous tire rolling radius value to increase or decrease based on the integrated value.

[0061] In addition, the error calculator 25 has feedback-related input information, i.e., the wheel speed estimation value inputted via the wheel speed input section 22 as input, and simultaneously receives the previous wheel speed observation value estimated by the observer module 23 as a feedback value, thereby calculating the speed error, i.e., the difference between the wheel speed estimation value and the previous wheel speed observation value. In other words, when the wheel speed input section 22 inputs the wheel speed measured by the wheel speed sensors 11 to 14, the gear ratio conversion speed, and the wheel speed estimation value determined based on the weight to the observer module 23, the error calculator 25 may be configured to calculate the speed error, i.e., the feedback value, between the wheel speed estimation value and the wheel speed observation value.

[0062] As described above, when the wheel speed input section 22 is configured to input the wheel speed value obtained from the signal of each wheel speed sensor 11 to 14 as the wheel speed estimation value to the observer module 23 without using the gear ratio conversion speed and weight, that is, when the wheel speed value is used as the input of the observer module 23, the error calculator 25 of the observer module 23 may be configured to calculate the wheel speed value and the speed error between the wheel speed value, that is, the feedback value. Then, the feedback control value calculator 26 may be configured to calculate the feedback control value of the acceleration scale, using which the speed error (that is, the observer error) calculated and input by the error calculator 25 converges to 0.

[0063] Specifically, the feedback control value calculator 26 may be configured to calculate a control value for correcting the speed error calculated and input by the error calculator 25 by taking the speed error as an input. The feedback control value calculator 26 may be referred to as a feedback error controller, and is configured to calculate and output a control value for setting the speed error to 0. According to an exemplary embodiment of the present invention, the feedback control value calculator 26 (which may be referred to as a feedback error controller) may be one selected from P gain control, I gain control, map-based control, and a composite control configuration, wherein the P gain control, I gain control, and map-based control are combined in parallel.

[0064] As in the theoretical concept of the controller, it is considered that there is a physical difference between the control input, the control feedback and the control target. Therefore, this provides a degree of freedom by which the scale of the feedback control input may not necessarily be limited to the acceleration scale. According to an exemplary embodiment of the present invention, the feedback gain of the feedback control value calculator 26 may be varied according to the wheel speed measured by the wheel speed sensors 11 to 14. The feedback gain may be determined as a function of the wheel speed. For example, at a lower wheel speed where the detection accuracy is lower, the feedback gain may be smaller.

[0065] Therefore, the speed error calculated by the error calculator 25 is the observer error. The feedback control value calculator 26, i.e., the feedback error controller, may be configured to calculate a feedback control value corresponding to the observer error by taking the observer error as a feedback input. In addition, according to the present invention, the feedback control value may be used as a compensation value with which the wheel acceleration output by the acceleration converter 24 is compensated. The compensation for the wheel acceleration may be performed by adding the wheel acceleration output by the acceleration converter 24 and the feedback control value (i.e., the compensation value).

[0066] In other words, in the observer module 23, when the wheel acceleration information output by the acceleration converter 24 is input to the adder 27 (i.e., the compensator) as the feedforward acceleration information, and at the same time, the feedback control value output by the feedback control value calculator 26 is input to the adder 27 as the feedback acceleration information, the adder 27 may be configured to add the wheel acceleration, i.e., the feedforward acceleration value, and the feedback control value of the error controller 20. In addition, the adder 27 may be configured to output the added wheel acceleration to the integrator 28.

[0067] The integrator 28 of the observer module 23 may be configured to calculate the wheel speed by integrating the wheel acceleration input by the adder 27. The wheel speed calculated by the integrator 28 may be directed through the direction corrector 29, which ultimately provides the directionality of the wheel speed according to the direction of wheel rotation, thereby obtaining a final wheel speed observation value, based on which the vehicle may be operated. Therefore, in the observer module 23, the wheel speed output by the integrator 28 (excluding the direction information indicating the direction of wheel rotation) may be corrected by the direction corrector 29, and thus, the wheel speed is finally estimated, that is, the final wheel speed observation value may be obtained as real-time information. The final wheel speed observation value is the wheel speed including information about the direction of wheel rotation (i.e., direction information).

[0068] The final wheel speed observation value obtained by the controller 20 is a wheel speed value including direction information. The direction corrector 29 of the observer module 23 provides the directionality of the wheel speed output by the integrator 28 according to the direction of wheel rotation. According to an exemplary embodiment of the present invention, the direction corrector 29 may be configured to determine the final wheel speed observation value from the engine speed, the wheel speed and the gear information, and the final wheel speed observation value provides the directionality due to the wheel rotation direction.

[0069] The engine speed used by the direction corrector 29 to add the direction information depending on the actual direction of wheel rotation to the wheel speed is the real-time engine speed detected by the engine speed sensor (or rotary transformer) 15. In addition, the wheel speed used by the direction corrector 29 to determine the final wheel speed observation value, that is, the wheel speed for which directionality has not yet been provided, is the wheel speed calculated and output by the integrator 28. In addition, when the direction corrector 29 provides directionality for the wheel speed, a different method can be applied to a vehicle that implements reverse drive using a transmission and a vehicle in an environmentally friendly vehicle, and reverse drive is implemented by rotating the engine in reverse without moving the transmission. When the engine rotates, the known rotary transformer 15, that is, the engine speed sensor 15, can be configured to output a signal indicating the engine speed and the direction of engine rotation.

[0070] Therefore, in a vehicle in which reverse drive is achieved by simply rotating the engine without moving the transmission, the direction corrector 29 can be configured to check whether there is a reverse drive input from the driver based on the gear information, obtain real-time direction information of the engine from the signal of the rotary transformer 15, and determine a final wheel speed observation value including information about the direction of rotation by adding the engine direction information to the wheel speed output by the integrator 28.

[0071] In contrast, in a vehicle that uses a transmission to achieve reverse drive, the vehicle's engine speed and actual wheel speed vary depending on the gear position, and the correlation between the current gear position and the wheel rotation direction is insufficient due to the intervention of the neutral range before or after the gear shift, synchronizer slip in the engine reverse rotation range, etc. Therefore, a strategy is needed to provide directionality to the wheel speed. Figure 3 Describe this in detail.

[0072] Figure 3 An example is shown in which the driver changes the gear to the reverse gear by operating the shift lever during the forward movement of the vehicle at a low speed, and then changes the gear to the drive gear during the reverse movement of the vehicle (i.e., the gear changes from the D gear to the R gear and then to the D gear). Figure 3 In the case of a vehicle that is not completely stopped even at a low speed, the driver changes the gear to the reverse gear. In addition, the driver changes the gear to the drive gear even at a low speed, the vehicle is not completely stopped even at a low speed.

[0073] However, if this happens, powertrain components such as the transmission may be damaged. Therefore, when changing gears between the drive gear and the reverse gear before the vehicle comes to a complete stop, as in the case where the gear is input as the reverse gear or the drive gear, a typical vehicle has a control process of rotating the engine, that is, the vehicle drive source rotates in the reverse direction and then rotates in the forward direction.

[0074] In the system for estimating wheel speed according to the present invention, the direction corrector 29 of the observer module 23 may include a direction determination module 29a configured to obtain real-time direction information corresponding to the actual rotation direction of the wheel speed, such as Figure 2 As shown, based on the engine speed and the gear shift state information of the transmission. In addition, the direction corrector 29 can be configured to determine the final wheel speed observation value (ie, the final estimated value) by adding the direction information obtained by the direction determination module 29a to the wheel speed output by the integrator 28.

[0075] Therefore, the wheel speed can be estimated by including the direction information to the wheel speed output by the integrator 28. In addition, although not shown, the wheel speed can also be estimated by including the direction information in the rotation speed of the wheel obtained from the signal of the wheel speed sensor. Therefore, the present invention also includes determining the wheel speed value (hereinafter referred to as "wheel speed drive / reverse information") by multiplying the rotation speed of the wheel detected by the wheel speed sensor as described above by the direction information (i.e., obtaining the driving / reverse information about the wheel speed as a value of "+1" or "-1" as described below).

[0076] exist Figure 3 In FIG. 1 , graph (a) represents the engine speed measured by the rotary transformer 15. The real-time engine speed information obtained by the rotary transformer 15 can be input to the direction determination module 29a of the direction corrector 29, such as Figure 2 In addition, the real-time engine speed information can be used to obtain the direction information of the wheel rotation using the gear information using the direction determination module 29a. It can be clearly seen from the figure that the engine speed information (a) obtained from the signal of the rotary transformer 15 can include direction information indicating the rotation direction of the engine.

[0077] According to the known rotary transformer 15, engine speed information with the directionality of forward / reverse rotation added thereto can be obtained. Figure 3 The engine speed (a) shown in, when the driver manipulates the reverse gear by the shift lever during the low-speed forward movement of the vehicle and when the driver manipulates the gear to the drive gear during the low-speed reverse movement of the vehicle, it can be understood that the engine, i.e., the vehicle driving source, rotates forward after the reverse rotation.

[0078] In other words, when the driver performs an operation to change the gear position to the reverse gear during the forward rotation of the driving engine, a control process is completed to reversely rotate the engine for a short time at a certain time point after the engine speed is decelerated, and the gear shift to the reverse gear at this time point is changed. Figure 3 ) and then rotate the engine forward after engine speed reduction. Figure 3 In the graph (a) of FIG. 1 , the engine speed having a positive (+) value indicates the forward rotation of the engine, and the engine speed having a negative (-) value indicates the reverse rotation of the engine. Figure 3 In the curve diagram (a), "a", "b", "c" and "d" relatively represent the time points when the engine rotation direction is changed and the engine speed passes through zero, while changing the engine rotation direction.

[0079] The time point when the first engine speed passes through zero point "a" is the time point when the engine starts to accelerate in reverse rotation after decelerating in forward rotation, and the time point when the second engine speed passes through zero point "b" is the time point when the engine restarts forward acceleration after decelerating in reverse rotation. After the time point when the first engine speed passes through zero point "a", the vehicle is in a forward moving state, the engine is in a reverse rotating state, the longitudinal acceleration has a positive (+) value, and the gear is changed to reverse gear.

[0080] In addition, before the second engine speed passes through zero, even when the engine is in reverse rotation deceleration and the gear is in reverse gear (i.e., R gear), the vehicle only decelerates in a low-speed forward motion state. In fact, the vehicle starts to move backward from the time point when the engine starts to rotate forward after the second engine speed passes through zero. In other words, the time point when the second engine speed passes through zero point "b", that is, the time point when the engine resumes forward rotation, is the time point when the vehicle starts to move in the reverse direction. After this point, even if the engine rotates forward, the vehicle continues to move in the reverse direction because the gear is in reverse gear (i.e., R gear).

[0081] Afterwards, when the driver performs an operation to change the gear position from the reverse gear (i.e., the R gear) to the drive gear (i.e., the D gear), a control process of causing the engine to rotate in the reverse direction for a short time at a certain time point after the engine speed is decelerated is completed, and the gear is shifted to the drive gear (i.e., the D gear) at this time point. Figure 3 ) and then rotate the engine forward after engine speed reduction. Figure 3 In the curve diagram (a), the time point when the third engine speed passes through the zero point "c" is the time point when the engine starts to accelerate in reverse rotation after decelerating in forward rotation, and the time point when the fourth engine speed passes through the zero point "d" is the time point when the engine restarts forward acceleration after decelerating in reverse rotation.

[0082] In addition, before the fourth engine speed passes through zero, even when the engine is in reverse rotation deceleration and the gear is in the drive gear (i.e., D gear), the vehicle decelerates only in a low-speed reverse motion state. In fact, the vehicle starts to move forward from the time point when the engine starts to rotate forward after the fourth engine speed passes through zero. In other words, the time point when the fourth engine speed passes through zero point "d", that is, the time point when the engine resumes forward rotation, is the time point when the vehicle starts to move forward. After this, when the engine rotates forward, the vehicle moves forward because the gear is in the drive gear (i.e., D gear).

[0083] also, Figure 3 The graph (b) in FIG. 1 shows the wheel speed information obtained by the wheel speed input section 22 using the signal of each wheel speed sensor 11 to 14. In an exemplary embodiment, the wheel speed input section 22 may be configured to calculate the wheel speed estimation value by a weighted summation method of multiplying the wheel speed and the gear ratio conversion speed by weights, respectively, and the obtained product, the wheel speed multiplied by the weights, is added to be the wheel speed information (b).

[0084] from Figure 3 As can be seen from the graph (b) in FIG. 1 , the wheel speed information obtained from the signal of each wheel speed sensor 11 to 14 does not include direction information indicating the direction of wheel rotation. Figure 3In the graph (b) in FIG. 1 , the wheel speed presents a minimum point of a positive (+) value without passing through a zero point when the engine resumes forward rotation after decelerating in reverse rotation. Thereafter, an increase in the wheel speed indicates an increase in reverse speed when the vehicle moves in reverse. Even when the gear position is switched between drive and reverse and between reverse and drive as described above, the signal of each wheel speed sensor 11 to 14 always indicates a positive (+) value, such as an absolute value, because the signal does not include direction information.

[0085] Figure 3 The curve graph (c) in FIG. 1 shows the gear information indicating the actual gear state of the transmission when the driver manipulates the gear lever in the order of drive gear, reverse gear, and drive gear (i.e., D gear→R gear→D gear). As shown in the figure, there is a neutral position (N) before and after the gear shift. Gear information, such as Figure 3 The curve diagram (b) in FIG. 1 may be information received by the controller of the wheel speed estimation system according to the present invention from another controller configured to collect gear information in real time, for example, a transmission control unit (TCU). In particular, the transmission control unit (TCU) in a typical vehicle is configured to receive information about the manipulation of the gear lever when the driver manipulates the gear lever. In addition, the transmission control unit (TCU) may be configured to receive real-time information about the operating state from the transmission while performing a shift control to operate the transmission in response to the driver manipulating the gear lever or based on the driving conditions of the vehicle.

[0086] In particular, the controller according to the present invention may be configured to receive real-time information indicating one of the drive gear state, neutral gear state and reverse gear state of the transmission (e.g., drive, neutral and reverse gear positions), i.e., gear information from the TCU. The direction determination module 29a of the direction corrector 29 according to the present invention may be configured to obtain information (d) by applying the function of the relay to the gear information (c), by which the gear state is classified into a drive direction and a reverse direction.

[0087] In other words, the direction determination module 29a of the direction corrector 29 can be configured to obtain information about the driving / reverse direction of the gear (hereinafter, referred to as "gear driving direction / reverse direction"), represented by the curve graph (d), from the gear information (c) by assigning "+1" to the state of converting the gear from the reverse gear to the driving gear after the neutral position is terminated and assigning "-1" to the state of converting the gear from the driving gear (D) to the reverse gear (R) after the neutral position (N) is terminated.

[0088] Then, at the time point when the rotation direction of the engine is changed after the gear shift, based on the engine speed information (a), that is, the time point when the engine speed passes through zero after checking the time point when the engine speed passes through zero, the direction determination module 29a of the direction corrector 29 can be configured to convert the engine speed drive / reverse information (e) to match the information about the gear drive / reverse (d).

[0089] In particular, the direction determination module 29a can be configured to check the time point when the rotation direction of the engine changes after the gear change based on the engine speed information (a), and to check the completion of the gear drive direction / reverse direction change (i.e., completion of shifting to the reverse gear or the drive gear) based on the information about the gear drive / reverse (d), so that the engine speed drive / reverse information (e) becomes matched with the gear drive direction / reverse direction when the gear drive / reverse change is completed.

[0090] The engine speed drive / reverse information (e) defines the engine speed drive / reverse that follows the gear drive / reverse (d). The gear drive / reverse (d) may be changed so that when the engine speed passes through zero after the gear drive / reverse (d) is changed, the engine speed drive / reverse (e) is converted to be the same as the gear drive / reverse (d).

[0091] In other words, when the engine speed (a) changes from forward rotation to reverse rotation due to the rotation direction being converted from a positive (+) value to a negative (-) value, a conversion may be performed so that the engine speed drive / reverse (e) is the same as the gear drive direction / reverse direction. For example, after the value of the gear drive / reverse (d) is converted from "+1" to "-1", when the zero crossing "a" of the engine speed (a) changes from a positive (+) value to a negative (-) value, the value of the engine speed drive / reverse (e) is converted from "+1" to "-1".

[0092] Similarly, after the value of the gear drive / reverse (d) is converted from "-1" to "+1", the value of the engine speed drive / reverse (e) is converted from "+1" to "-1" when the zero crossing "c" of the engine speed (a) changes from a positive (+) value to a negative (-) value. In addition, the direction determination module 29a of the direction corrector 29 can be configured to obtain information about the forward / reverse rotation direction of the engine speed indicated by (f) based on the engine speed information (a). The information about the forward / reverse rotation direction of the engine speed (f) can be determined as "+1" when the engine rotates forward, and as "-1" when the engine rotates reversely.

[0093] Subsequently, the direction determination module 29a of the direction corrector 29 may be configured to obtain the wheel speed drive / reverse information indicated by (g) by multiplying the value "+1" or "-1" of the engine speed drive / reverse information (e) by the value "+1" or "-1" of the information of the forward / reverse rotation direction of the engine speed (f). In the wheel speed drive / reverse information (g), "+1" indicates when the wheel rotates in the driving direction, and "-1" indicates when the wheel rotates in the reverse direction. The values ​​"+1" and "-1" are direction information indicating the direction of wheel rotation.

[0094] Therefore, when the direction corrector 29 adds the direction information depending on the wheel rotation direction to the wheel speed (excluding the direction information indicating the wheel rotation direction) output by the integrator 28 of the observer module 23, the wheel speed to which the directionality of the wheel rotation is added, i.e., the final wheel speed observation value according to the present invention, can be obtained. In particular, the direction corrector 29 can be configured to calculate the final wheel speed observation value by multiplying the wheel speed (excluding the direction information indicating the wheel rotation direction) output by the integrator 28 by the value "+1" or "-1" of the wheel speed drive / reverse information (g).

[0095] exist Figure 3 , the curve (h) represents the final wheel speed observation value, that is, the final estimation result value observed by adding directionality according to the above process of the present invention. Therefore, the wheel speed estimation system and method according to the present invention can obtain more accurate wheel speed information in a relatively short update cycle, thereby operating the vehicle accordingly. Even when the vehicle is traveling at an extremely low speed when crawling, a more accurate wheel speed value reflecting the actual situation of the wheel can be obtained as real-time information. Therefore, the overall driving performance of the vehicle can be improved.

[0096] In particular, in the wheel speed estimation system and method according to the present invention, it is possible to obtain a wheel speed value including real-time rotation direction information from, for example, a situation in which the driver inputs a reverse drive input (i.e., performs an R range manipulation) during low-speed driving. Therefore, it is possible to overcome problems that occur when only the wheel speed sensors 11 to 14 are used, such as reduced resolution in a low-speed range and no information on the rotation direction.

[0097] In addition, according to the present invention, the accuracy of the wheel speed information in the low speed range can be improved while obtaining the direction information of the wheel rotation using the existing wheel speed sensors 11 to 14 without using expensive wheel speed sensors. Therefore, the performance of chassis control (e.g., anti-lock braking system (ABS), traction control system (TCS), or hill start assist control (HAC) system) and the performance of drive system related control (e.g., transmission control, torque command generation, or four-wheel drive control) can be improved, and excellent driving performance can be guaranteed.

[0098] According to another exemplary embodiment of the present invention, speeds of non-driven wheels instead of driven wheels, wheel speed values ​​of wheel speed changes obtained from global positioning system (GPS) information, or wheel speeds observed based on a vehicle model may be used instead of wheel speeds.

[0099] In addition, although the engine speed has been described as an example of the speed of the vehicle drive source connected to the input side of the transmission, the engine speed may be replaced by the rotation speed of the drive system (e.g., engine speed), the starter engine speed, or the speed of the transmission input shaft. In addition, instead of using the P controller 20 or the I controller 20 provided by the feedback control value calculator 26, which may be referred to as a feedback error controller, a Kalman filter or a controller 20 obtained by pole configuration may be provided. Any other configuration in which the observer error is used as the feedback (FB) input may be used without limitation.

[0100] Although exemplary embodiments of the present invention have been described for illustrative purposes, the scope of the present invention is not limited thereto. It should be understood that various modifications and improvements will be apparent to those skilled in the art without departing from the scope and spirit of the present invention disclosed in the appended claims.

Claims

1. A system for estimating wheel speed of a vehicle, wherein: The vehicle includes a driving engine and a transmission, and the vehicle uses the transmission to perform reverse motion, and the system includes: a wheel speed sensor configured to detect a rotation speed of a wheel of the vehicle; an engine speed sensor configured to detect a speed of the drive engine; and a controller configured to receive a signal of the wheel speed sensor, a signal of the engine speed sensor, and information about a gear indicating a current gear state of the transmission, and the controller estimates a wheel speed to which a directionality of wheel rotation is added, wherein the controller comprises a direction determination module configured to obtain direction information indicating the direction in which the wheel rotates from engine speed information and gear information, the engine speed information being obtained from a signal of the engine speed sensor, and wherein, when the gear is changed to a reverse gear by operating a gear lever during the low-speed forward movement of the vehicle or the gear is changed to a drive gear during the low-speed reverse movement of the vehicle, the controller is configured to estimate the wheel speed including the directionality of the wheel rotation using the real-time direction information obtained by the direction determination module and the signal of the wheel speed sensor, Wherein, the controller includes an observer module; Wherein, the observer module, determining wheel acceleration using longitudinal acceleration information of the vehicle obtained from a signal of a longitudinal acceleration sensor, calculating a speed error, which is the difference between the wheel speed estimate and a previous wheel speed observation, calculating a feedback control value of the acceleration scale for setting the speed error to zero, compensating the determined wheel acceleration with the feedback control value, and then determining the wheel speed by integrating the compensated wheel acceleration, The direction determination module obtains engine speed information from the signal of the engine speed sensor, and obtains direction information indicating the rotation direction of the wheel from the gear information. The wheel speed assigned to the direction of wheel rotation is estimated using real-time direction information obtained by the direction determination module from the wheel speed determined by integration.

2. The system according to claim 1, wherein: The direction determination module is configured to obtain information about the driving direction / reverse direction of the gear from the gear information after the neutral range ends, assigning "+1" to the driving movement and assigning "-1" to the reverse movement.

3. The system according to claim 2, wherein: The direction determination module is configured to determine information about the driving direction / reverse direction of the engine speed, and the information about the driving direction / reverse direction of the engine speed matches information about the driving direction / reverse direction of the gear at a time point when the rotation direction of the driving engine changes to one of "+1" and "-1".

4. The system according to claim 3, wherein: The direction determination module is configured to obtain information about the forward rotation direction / reverse rotation direction of the engine speed, assigning "+1" to the forward rotation of the drive engine and assigning "-1" to the reverse rotation of the drive engine.

5. The system according to claim 4, wherein: The direction determination module is configured to determine real-time direction information of the wheel rotation, which is information about the driving direction / reverse direction of the wheel speed from a value obtained by multiplying the determined information about the driving direction / reverse direction of the engine speed with the obtained information about the forward rotation direction / reverse rotation direction of the engine speed.

6. The system according to claim 2, wherein: The direction determination module is configured to check a point in time when the rotation direction of the driving engine changes after a gear shift based on the engine speed information obtained through a signal of the engine speed sensor, and the direction determination module is configured to determine the information about the driving direction / reverse direction of the engine speed as the same value as the information about the driving direction / reverse direction of the gear at the point in time when the rotation direction of the driving engine changes.

7. The system according to claim 6, wherein: The direction determination module is configured to check a time point at which the engine speed obtained by a signal of the engine speed sensor passes through a positive "+" value through a zero point to a negative "-" value as a time point at which the rotation direction of the driving engine changes after shifting, and the direction determination module is configured to determine the information about the driving direction / reverse direction of the engine speed as the same value as the information about the driving direction / reverse direction of the gear at the time point at which the engine speed passes through the zero point from the positive "+" value to the negative "-" value.

8. The system according to claim 6, wherein: The direction determination module is configured to maintain information about the driving direction / reverse direction of the engine speed, which is determined to be the same value as the information about the driving direction / reverse direction of the gear, until a next time point at which the rotation direction of the driving engine changes after shifting gears again.

9. The system according to claim 2, wherein: The controller is configured to estimate the wheel speed to which the directionality of wheel rotation is added by multiplying information on the driving direction / reverse direction of the wheel speed determined by the direction determination module and a rotation speed of the wheel obtained from a signal of the wheel speed sensor.

10. The system according to claim 1, wherein: The wheel speed sensor includes an encoder.

11. The system according to claim 1, wherein: The engine speed sensor includes a resolver.

12. A method for estimating the wheel speed of a vehicle, wherein: The vehicle comprises a driving engine and a transmission, and the vehicle performs reverse motion using the transmission, and the method comprises the following steps: The controller receives: a signal from a wheel speed sensor, a signal from an engine speed sensor, and information about a gear indicating a current gear state of the transmission; obtaining, by the controller, engine speed information obtained by the direction determination module from the signal of the engine speed sensor and direction information indicating the direction of wheel rotation obtained from the information about the gear position; and When the gear position is changed to a reverse gear by operating a shift lever during the low-speed forward movement of the vehicle or the gear position is changed to a drive gear during the low-speed reverse movement of the vehicle, the controller estimates the wheel speed to which the directionality of the wheel rotation is added using the signal from the wheel speed sensor and the real-time direction information obtained by the direction determination module, Wherein, the controller includes an observer module; Wherein, the observer module, determining wheel acceleration using longitudinal acceleration information of the vehicle obtained from a signal of a longitudinal acceleration sensor, calculating a speed error, which is the difference between the wheel speed estimate and a previous wheel speed observation, calculating a feedback control value of the acceleration scale for setting the speed error to zero, compensating the determined wheel acceleration with the feedback control value, and then determining the wheel speed by integrating the compensated wheel acceleration, The direction determination module obtains engine speed information from the signal of the engine speed sensor, and obtains direction information indicating the rotation direction of the wheel from the gear information. The wheel speed assigned to the direction of wheel rotation is estimated using real-time direction information obtained by the direction determination module from the wheel speed determined by integration.

13. The method according to claim 12, wherein: Acquiring the direction information includes the following steps: The controller obtains information about the driving direction / reverse direction of the gear from the gear information after the neutral range ends, assigning "+1" to the driving movement and assigning "-1" to the reverse movement; determining, by the controller, information on the driving direction / reverse direction of the engine speed, the information on the driving direction / reverse direction of the engine speed conforming to information on the driving direction / reverse direction of the gear at a time point when the rotation direction of the driving engine changes to one of "+1" and "-1"; obtaining, by the controller, information on the forward rotation direction / reverse rotation direction of the engine speed, assigning "+1" to the forward rotation of the drive engine and assigning "-1" to the reverse rotation of the drive engine; and The controller determines real-time direction information of the wheel rotation, which is information about the driving direction / reverse direction of the wheel speed, from a value obtained by multiplying the determined information about the driving direction / reverse direction of the engine speed with the obtained information about the forward rotation direction / reverse rotation direction of the engine speed.

14. The method according to claim 13, wherein: When determining the information about the driving direction / reverse direction of the engine speed, the time point when the rotation direction of the driving engine changes after the gear shift is checked based on the engine speed information obtained through the signal of the engine speed sensor, and the information about the driving direction / reverse direction of the engine speed is determined to be the same value as the information about the driving direction / reverse direction of the gear at the time point when the rotation direction of the driving engine changes.

15. The method according to claim 14, wherein: The time point at which the engine speed obtained by the signal of the engine speed sensor changes from a positive "+" value through zero to a negative "-" value is checked as the time point at which the rotation direction of the driving engine changes after shifting, and at the time point at which the engine speed changes from the positive "+" value through zero to the negative "-" value, the information about the driving direction / reverse direction of the engine speed is determined to be the same value as the information about the driving direction / reverse direction of the gear.

16. The method according to claim 14, wherein: The information about the driving direction / reverse direction of the engine speed, which is determined to be the same value as the information about the driving direction / reverse direction of the gear, is maintained until the next time point when the rotation direction of the driving engine changes after shifting gears again.

17. The method according to claim 13, further comprising the steps of: The wheel speed to which the directionality of the wheel rotation is added is estimated by the controller by multiplying information on the driving direction / reverse direction of the wheel speed determined by the direction determination module and the rotation speed of the wheel obtained from the signal of the wheel speed sensor.

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