DEVICE FOR WHEEL SPEED ESTIMATING AND VEHICLE EQUIPPED WITH IT

Abstract

Device for wheel speed estimation, the device comprising: an electric drive train including an electric motor (107) providing a motor speed, a wheel (105), and a mechanical coupling between the motor (107) and the wheel (105), the mechanical coupling between the motor (107) and the wheel (105) comprising a gearbox (109) and a drive axle (102); and an electronic control unit (117) that calculates an estimated wheel speed based on the motor speed and mechanical dynamic models of the electric drive train; characterized in that the mechanical dynamic models of the electric drive train include the drive axle (102) being modeled as an active component that includes a torsional spring constant (k), a torsional damping constant (c), a rotation angle (θ1) at an output of the gearbox (109), and a rotation angle (θ2) at the wheel (105);wherein the mechanical dynamic models of the electric drive train further comprise a rotational replacement model (405, 407) of the electric motor (107) and the transmission (109); and wherein the estimated wheel speed is calculated from a second-order transfer function derived from the mechanical dynamic models of the electric drive train;

Description

INTRODUCTION

[0001] This disclosure concerns electric vehicles.

[0002] Electric vehicles can be equipped with speed sensors at various points within the electric drive system. Speed ​​can be used for various functions and controls. Speed ​​sensing of electric drive system motors can be used to control such motors. Speed ​​sensing of drive wheels can be used for a variety of controls related to the propulsion, suspension, steering, and braking systems. The loss of drive wheel speed sensing at any wheel of the vehicle can negatively affect the behavior of systems that rely on the speed of a single drive wheel. Furthermore, wheel speed sensing can have limited resolution at low vehicle speeds, which can negatively affect the behavior of systems that depend on accurate wheel speed sensing at low vehicle speeds. SUMMARY

[0003] According to an exemplary embodiment, a device for wheel speed estimation may include an electric drive train comprising an electric motor providing a motor speed, a wheel and a mechanical coupling between the motor and the wheel, and an electronic control unit that calculates an estimated wheel speed based on the motor speed and mechanical dynamic models of the electric drive train.

[0004] In addition to one or more of the features described here, the electronic control unit can synchronize the engine speed with a detected wheel speed.

[0005] In addition to one or more of the features described here, the electronic control unit can process a detected wheel speed.

[0006] In addition to one or more of the features described here, the mechanical coupling between the motor and the wheel may include a gearbox and a drive axle.

[0007] In addition to one or more of the features described here, the mechanical dynamic models of the electric powertrain may include the drive axle being modeled as an active component that contains a torsional spring constant, a torsional damping constant, a rotation angle at a gearbox output, and a rotation angle at the wheel.

[0008] In addition to one or more of the features described here, the mechanical dynamic models of the electric powertrain may also include a rotational equivalent model of the electric motor and gearbox.

[0009] In addition to one or more of the features described here, the estimated wheel speed can be calculated from a second-order transfer function derived from the mechanical dynamic models of the electric powertrain.

[0010] In addition to one or more of the features described here, the fact that the electric motor provides a motor speed may include the fact that the electric motor provides the motor speed based on a motor speed encoder.

[0011] According to another exemplary embodiment, a method for wheel speed estimation in an electric powertrain may include driving a wheel with an electric motor and calculating an estimated wheel speed based on the speed of the electric motor and mechanical dynamic models of the electric powertrain.

[0012] In addition to one or more of the features described here, the speed of the electric motor can be synchronized with a detected wheel speed.

[0013] In addition to one or more of the features described here, the electric powertrain may include a drive axle that is mechanically coupled between the wheel and the electric motor, and the mechanical dynamic models of the electric powertrain may include the drive axle being modeled as an active component that includes a torsional spring constant, a torsional damping constant, a rotation angle at an input end of the drive axle, and a rotation angle at the wheel.

[0014] In addition to one or more of the features described here, the electric drive train may also include a gearbox that is mechanically coupled between the electric motor and the drive axle, and the mechanical dynamic models of the electric drive train may also include a rotational equivalent model of the electric motor and the gearbox.

[0015] In addition to one or more of the features described here, the estimated wheel speed can be calculated from a second-order transfer function derived from the mechanical dynamic models of the electric powertrain.

[0016] According to yet another exemplary embodiment, a vehicle powered by an electric motor can include an electric drivetrain comprising an electric drive unit that includes an electric motor mechanically coupled to an input of a gearbox and a motor controller that provides a motor speed from a rotary encoder. Furthermore, the electric drivetrain can include a wheel and a drive axle that mechanically couples the wheel to an output of the gearbox.Furthermore, the vehicle powered by an electric motor may contain an electronic control unit that calculates an estimated wheel speed based on the motor speed and mechanical dynamic models of the electric powertrain, processes the detected wheel speed from a wheel speed sensor, and provides the detected wheel speed and the estimated wheel speed to a vehicle subsystem that is controlled based on the wheel speed information.

[0017] In addition to one or more of the features described here, the vehicle subsystem may include an electric propulsion subsystem and / or a suspension subsystem and / or a steering subsystem and / or a brake subsystem.

[0018] In addition to one or more of the features described here, the mechanical dynamic models of the electric powertrain may include the drive axle being modeled as an active component that contains a torsional spring constant, a torsional damping constant, a rotation angle at a gearbox output, and a rotation angle at the wheel.

[0019] In addition to one or more of the features described here, the mechanical dynamic models of the electric powertrain may also include a rotational equivalent model of the electric motor and gearbox.

[0020] In addition to one or more of the features described here, the estimated wheel speed can be calculated from a second-order transfer function derived from the mechanical dynamic models of the electric powertrain.

[0021] In addition to one or more of the features described here, the estimated wheel speed can be used by the vehicle subsystem if the detected wheel speed is faulty.

[0022] In addition to one or more of the features described here, the estimated wheel speed can be used by the vehicle subsystem at low vehicle speeds.

[0023] The above features and advantages, and further features and advantages of the disclosure, are easily evident from the following detailed description when taken together with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Further features, advantages and details appear only as examples in the following detailed description, which refers to the drawings; they show: Fig. 1 schematically an exemplary vehicle which may include an electric propulsion subsystem and other subsystems according to the present disclosure; Fig. 2 a routine for performing various tasks in accordance with the present disclosure; Fig. 3 a graphical representation of a one-dimensional interpolation according to the present disclosure; Fig. 4 a simplified schematic representation of the final drive according to the present disclosure; and Fig. 5 rotation models according to the present disclosure. DETAILED DESCRIPTION

[0025] The following description is by its very nature merely exemplary and is not intended to limit the present disclosure, its application, or uses. Corresponding reference numerals throughout the drawings indicate identical or corresponding parts and features.

[0026] The various figures are schematic representations, and the absolute or relative scaling of the different features depicted here is not intended to have or be interpreted as meaning. Identical reference symbols in multiple figures refer to the same or identical components.

[0027] Fig. Figure 1 schematically represents an exemplary vehicle 101, which may include an electric propulsion subsystem 103. The electric propulsion subsystem 103 may include various control components, electrical and electromechanical systems, including, for example, a rechargeable energy storage system (RESS) 104 and at least one electric drive unit (EDU) 111. The electric propulsion subsystem 103 can be used in powertrain systems to generate propulsion torque in various electric vehicle (EV) applications or hybrid electric vehicle (HEV) applications, either as a replacement for or in conjunction with an internal combustion engine. The vehicle 101 is depicted as a battery electric vehicle (BEV), and the RESS 104 is a battery assembly (e.g., with 400 V DC), although other EVs or HEVs could be used.Propulsion torque requests or propulsion torque commands can be provided to a power electronics module 113 by means of a control system 115. According to one embodiment, the vehicle 101 is shown as a two-axle, four-wheeled vehicle, although it should be noted that any other vehicles containing one or more axles and one or more wheels for on-road or off-road use can also be used. Axle can refer to a pair of laterally opposed wheels on a vehicle, which do not necessarily include a physical axle between them. Wheel can refer to a single wheel or to multiple wheels on one side of an axle, such as those found, for example, on a van's double rear axle. The electric propulsion subsystem 103 can be used for one or more wheels 105 located at the front of the vehicle (F) (i.e., front left (LF) and front right (RF)) and at the rear of the vehicle (R) (i.e., the rear left (LF) and rear right (RF)).h. left rear (LR) and right rear (RR)) are located, provide a propulsive torque or react to a braking torque from it.

[0028] The vehicle 101 can include a front axle 116 corresponding to the front wheels 105. Front-wheel steering can be effected by a front-wheel steering mechanism 180, which may include a steering gear and steering linkage. The steering input (i.e., operator interface) can be provided by a mechanical steering shaft interacting with the steering gear. The mechanical steering effort can be assisted by hydraulic or electrical devices. Alternatively, an electronic steering system is available in which the operator's steering intention is determined and, together with other information such as vehicle speed and yaw rate, can actuate the steering gear without the need for the mechanical steering shaft to interact with the steering gear. Front-wheel steering angle information can be available via a front-wheel steering angle sensor 181.

[0029] The vehicle 101 can include a rear axle 114 corresponding to the rear wheels 105. Rear-wheel steering can be effected by a rear-wheel steering mechanism 106, which may include a steering gear and steering linkage. The rear-wheel steering mechanism 106 can include an actuator 110 that causes the steering gear to steer the rear wheels 105 in the desired direction. According to one embodiment, the actuator 110 can be, for example, a rotary electric motor, an electric linear motor, a hydraulic actuator, or a combination thereof, such as an electro-hydraulic actuator. Other actuators may be known to the person skilled in the art. According to another embodiment, the rear-wheel steering mechanism 106 can include individual mechanisms with actuators at the wheel, such as independent electric actuators. Rear-wheel steering angle information can be available via a rear-wheel steering angle sensor 181.

[0030] The electric drive unit 103 can include at least one EDU 111. Each EDU 111 can have varying complexity, components, and integration. According to one embodiment, the EDU 111 can include at least one electric traction motor 107, at least one gearbox 109, and at least one power electronics module 113. The EDU 111 is part of an electric drive train that includes a motor and final drive components, which include a gearbox, a wheel assembly, and other torque transmission components that mechanically couple the motor to the wheel assembly. The power electronics module 113 can include a motor controller and a traction power converter and can include other power electronics such as an accessory power module and an on-board charging module. The power electronics module can perform motor control and motor diagnostics.The motor 107 can be a multi-phase AC motor, such as a three-phase AC motor, receiving three-phase AC power via a multi-phase motor control power bus (AC bus) coupled to the traction power converter. According to one embodiment, the motor 107 can be a three-phase motor, and the traction power converter can be a three-phase converter. The traction power converter can include multiple solid-state switches, such as IGBTs and power MOSFETs. The traction power converter can receive DC power via a high-voltage DC bus (HV DC bus) coupled to the RESS. The motor controller of the power electronics module 113 can be coupled to the traction power converter for its control. The traction power converter can be electrically connected to the motor 107 via the AC bus, with the electrical current on two or three of its lines being monitored.The traction power converter can be configured with suitable control circuitry, including paired power transistors (e.g., IGBTs), to transform high-voltage DC electrical power into high-voltage AC electrical power and vice versa. The traction power converter can utilize pulse-width modulation (PWM) control to convert stored DC electrical power from the RESS into AC electrical power to drive the motor 107 to generate torque. Similarly, the traction power converter can convert mechanical power transferred to the motor 107 into DC electrical power to generate electrical energy that can be stored in the RESS, including as part of a regenerative braking control strategy.It will be appreciated that the traction power converter can be configured to receive motor control commands from the motor controller of the power electronics module 113 and to control converter states to provide motor drive and recovery functionality.

[0031] According to the illustrated embodiment Fig. The electric drive subsystem 103 comprises a single-motor front axle configuration with an EDU 111 containing a motor MA 107, which provides drive torque to the LF wheel 105 and the RF wheel 105, and a two-motor rear axle configuration with an EDU 111 containing a motor MB 107, which provides drive torque to the LR wheel 105, and a motor MC 107, which provides drive torque to the RR wheel 105. The motors 107 are mechanically coupled to the respective wheels 105 via respective transmissions 109, which may include reduction gears, transmission shafts, and differential gears as required, and other final drive components such as drive axles 102. A drive axle 102 can be a simple shaft or it can include a pair of constant velocity joints (CV joints) at opposite ends. The drive axle 102 can, for example,by means of wedge profile connections, at one end to the gearbox 109 at an output and at the other end to the wheel 105. According to the exemplary embodiment shown. Fig. 1. The motor MA 107 can be mechanically coupled to both the LF and RF wheels via a front gearbox 109, which integrates a reduction gear set, differential gears, and respective drive axles 102. Such a gearbox can provide a single gear ratio or several controllably engageable gear ratios. Such a gearbox can include an input mechanically coupled to the motor MA 107, an LF output mechanically coupled to the LF wheel 105 via an LF drive axle 102 and a respective wheel hub, and an RF output mechanically coupled to the RF wheel 105 via an RF drive axle 102 and a respective wheel hub. According to the exemplary embodiment shown in Figure 1, the following applies: Fig. 1. The MB 107 motor can be mechanically coupled to the LR wheel 105 via a rear gearbox 109, which includes a reduction gear set and a drive axle 102. Such a gearbox can provide a single gear ratio or several controllably engaged gear ratios. Since the MB 107 motor is only mechanically coupled to the LR wheel 105, such a gearbox does not include a differential gear. Such a gearbox can have an input mechanically coupled to the MB 107 motor and an LR output mechanically coupled to the LR wheel 105 via an LR drive axle 102 and respective wheel hubs. Similarly, the MC 107 motor can be mechanically coupled to the RR wheel 105 via a rear gearbox 109, which includes a reduction gear set and a drive axle 102.Such a transmission can provide a single gear ratio or several controllably engaged gear ratios. Since the motor MC 107 is only mechanically coupled to the RR wheel 105, such a transmission does not contain a differential gear. Such a transmission can include an input mechanically coupled to the motor MC 107 and an RR output mechanically coupled to the RR wheel 105 via an RR drive shaft 102 and a respective wheel hub. The embodiment shown in... Fig. Figure 1 is exemplary and other mechanical arrangements and power-split configurations, including a single-engine configuration with one or more gearboxes providing engine torque distribution to one or more wheels, a single-engine rear axle configuration, a twin-engine front axle configuration, integrated wheel-engine configurations and various combinations thereof, are considered.

[0032] The EDUs 111 can, for example, provide respective motor speeds via high-resolution motor encoders 108. The motor speed can be provided using alternative methods, including sensorless techniques. The encoders 108 can provide rotation information to a respective power electronics module 113. The motor encoder information can be processed by the power electronics module 113 to derive motor speed and related quantities such as acceleration and angular position, angular velocity, and angular acceleration for use by the power electronics module 113 in controlling the respective motor 107.

[0033] The vehicle 101 may include a control system 115, which may contain one or more electronic control units (ECUs) 117. The control system 115 may be responsible for functions relating to the control and diagnosis of the electric propulsion subsystem 103, including, for example, power operating modes, torque request sensing and validation, torque management including limits, rates and arbitrations, gear ratio and differential control, RESS charge state, RESS operating state and thermal RESS management. Furthermore, the control system 115 may be responsible for control functions relating to other subsystems of the vehicle 101, including, for example, the suspension subsystem 50, the steering subsystem 60 and the brake subsystem 70.The Vehicle 101 may include an electronic brake control system that can incorporate friction brake application and traction motor control (recuperative braking counter-torque). The electronic brake control system may include anti-lock braking functions. The Vehicle 101 may include an electronic traction control system that can incorporate friction brake application and traction motor control (propulsion torque). The Vehicle 101 may include an electronic stability control system that can incorporate friction brake application, traction motor control (propulsion torque / braking torque), electronic steering control (front and / or rear), and active or semi-active electronic suspension control. The Vehicle 101 may include active rear-wheel steering control for low-speed maneuverability (reduced turning radius and lateral "crab steering") and for high-speed stability, such as during towing.The vehicle 101 may include advanced driver assistance systems (ADAS) at various levels, which may include friction brake application, traction motor control (propulsion torque / braking torque), electronic steering control (front and / or rear), and active or semi-active control of the electronic suspension.

[0034] As used here, electronic control unit (ECU), control module, module, control, controller, control unit, processor and similar terms mean any or various combinations of one or more application-specific integrated circuits (ASICs), electronic circuits, central processing units (preferably microprocessors) and associated memory and storage memory (read-only memory (ROM), read / write memory (RAM), electronically programmable read-only memory (EPROM), hard disk drive, etc.).) or microcontrollers executing one or more software or firmware programs or software or firmware routines, combination logic circuits, input / output (I / O) circuits and devices, suitable signal conditioning and buffering circuits, a fast clock, analog-to-digital (A / D) and digital-to-analog (D / A) circuits, and other components to provide the described functionality. An ECU may include a variety of communication interfaces, including point-to-point or discrete lines and wired or wireless interfaces to networks, including wide area networks (WANs) and local area networks (LANs), vehicle controller area networks (VANs), and internal and customer service networks.Functions of an ECU or control system, as set forth in this disclosure, can be executed in a distributed control architecture among multiple networked ECUs. Software, firmware, programs, instructions, routines, code, algorithms, and similar terms mean any sets of instructions executable by the ECU, including calibrations, data structures, and lookup tables. An ECU may have a set of control routines that are executed to provide the described functions. Routines are executed as if by a central processing unit and can be operated to monitor inputs from sensing devices and other networked ECUs, and to execute control and diagnostic routines for controlling the operation of actuators. Routines can be executed at regular intervals during continuous power engine and vehicle operation.Alternatively, routines can be executed in response to the occurrence of an event, software calls, or, if required, via user interface inputs or user interface requests.

[0035] The vehicle's control system 115 101 can include numerous ECUs 117, sensors 119, and vehicle user interface devices 121. It can communicate via a communication network 123 and perform control functions and information sharing, including the execution of control routines, both locally and in a distributed manner. The communication network can include wired and wireless communications, such as a Controller Area Network (CAN) or short-range wireless communications (SRWC), using appropriate communication protocols for information sharing and routing.The ECUs 117 can include such non-restrictive examples as vehicle control modules (VCMs), powertrain control modules (PCMs), power electronics modules 113, engine control modules (ECMs), transmission control modules (TCMs), body control modules (BCMs), electronic brake control modules (EBCMs), traction control or stability control modules, cruise control modules, chassis / suspension control modules, steering control modules, etc. The ECUs 117 can be connected (e.g., via the communication network 123) indirectly or directly to a variety of sensors and actuators, as well as to other ECUs 117. The sensors 119 can include, among others, engine rotary encoders and wheel speed sensors. User interface devices can include, among others, accelerator and brake pedals, steering wheels, touchscreens, gesture and dialogue managers.

[0036] The control system 115 can access a variety of information from sensors 119 and various ECUs 117 for use in controlling the various vehicle subsystems, including the electric propulsion subsystem 103, the suspension subsystem 50, the steering subsystem 60, and the brake subsystem 70, to effect desired functions. Information accessed by the control system 115 may include such non-limiting examples as vehicle dynamics and vehicle kinematics information such as speed, direction of travel, steering angle, multi-axis accelerations and multi-axis jerk, yaw, pitch, roll, and their derivatives, etc. Such information may be generally available via the communication network 123, for example, byfrom vehicle sensors such as wheel speed sensors 171, which detect the rotation of the wheels 105 at each corner of the vehicle 101, front and rear steering angle sensors 181, and yaw rate sensors. The sensors 119 can provide information as discrete inputs to various directly coupled ECUs 117 or can provide information to the communication network 123. Regardless of this, sensor information, e.g., where a sensor can act as a network node device or where sensor information is made generally available in the communication network via a directly coupled ECU 117, can be accessible to various ECUs 117 via the communication network 123. According to one embodiment, an EBCM 118 can directly monitor wheel speed sensors 171, process (e.g., filter) the information, and provide wheel speed information for access by other ECUs 117 via the communication network 123.Wheel speed information based on wheel speed sensors can be referred to as detected wheel speed or detected wheel speed information. As used here, an EBCM means an ECU that, regardless of whether the brake subsystem control is executed in the EBCM, monitors wheel speed sensors 171, processes wheel speed information from wheel speed sensors 171, and provides wheel speed information for use by other ECUs 117. Similarly, engine speed information for each engine 107 can be based on an engine speed encoder and provided by respective power electronics modules 113 for access by the other power electronics modules 113 and other ECUs 117 via the communication network 123.

[0037] Wheel speed information, along with other sensor information and vehicle parameters, can be used in various vehicle control functions. For example, the electric propulsion subsystem 103, the suspension subsystem 50, the steering subsystem 60, and the brake subsystem 70 can all use wheel speed information to control different actuators and achieve various desired functions. Therefore, the control of the electric propulsion subsystem 103, the suspension subsystem 50, the steering subsystem 60, and the brake subsystem 70 may require or depend on the integrity of wheel speed information. It can be said that the control of a subsystem that uses wheel speed information is either reliant on or dependent upon wheel speed information.For example, the electric propulsion subsystem 103 can use individual wheel speed information at each corner of the vehicle for torque vectoring and electronic differential control. The suspension subsystem 50 can use wheel speed information for pitch control, brake dive, and launch control. The steering subsystem 60 can use wheel speed information for front and rear steering angle control during slow and fast maneuvers. Additionally, the brake subsystem 70 can use wheel speed information for traction control, stability control, and anti-lock braking control.

[0038] The control system 115 can perform diagnostic and recovery routines for the detected wheel speed, thereby enabling engine speed information from the EDUs 111 to provide a source of redundancy and backup for detected wheel speed information. According to one embodiment, the EBCM 118 can perform a function as described in Fig. 2. Execute routine 201 as shown. The routine may be stored in a non-transitory, computer-readable storage medium and may contain computer-readable program instructions to cause a processor to execute aspects of the present disclosure. The computer-readable storage medium may be a specific device capable of storing and retaining instructions for use by an instruction-executing device. The computer-readable storage medium may be, for example, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination thereof, but is not limited to such.A non-exhaustive list of specific examples of computer-readable storage media includes the following: a portable computer floppy disk, a hard disk, read / write memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static read / write memory (SRAM), portable compact disc read-only memory (CD-ROM), digital versatile disc (DVD), memory stick, a mechanically coded device, and any suitable combination of the foregoing. A computer-readable storage medium, as used here, is not to be understood as containing transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission medium (e.g., a cable).These are light pulses passing through a fiber optic cable, or electrical signals transmitted over a wire. The computer-readable program instructions can also be loaded into a computer, other programmable data processing device, or other equipment to cause a series of operational tasks to be performed in the computer, other programmable device, or other equipment in order to produce a computer-implemented process such that the instructions executed in the computer, other programmable device, or other equipment implement the functions / activities specified in the flowchart and / or block diagram block(s) of the [document / section]. Fig. The routine 201 shown in section 2 is explained as an example.

[0039] Routine 201 initializes at 203, where engine diagnostic data is provided by the power electronics modules 113 of the EDUs 111 and read into the EBCM 118. Although routine 201 may be described with respect to a single corner of the vehicle, it evaluates all corners of the vehicle. At 205, an engine speed fault check is performed to determine whether the engine speed information is considered good, e.g., whether the encoder 108 and the wiring harness are free of open circuits and short circuits, and whether the engine speed information is free of speed errors. Such a fault check may involve checking fault flag information passed from the power electronics module 113 to the EBCM 118, or processing engine speed information at the EBCM 118 in a local diagnostic routine.An engine speed fault at 205 causes routine 201 to proceed to 207, while the absence of an engine speed fault causes routine 213 to proceed. At 207, a fault check of the detected wheel speed is performed to determine whether the detected wheel speed is considered good, e.g., whether the wheel speed sensor 171 and the wiring harness are free of open circuits and short circuits, and whether the detected wheel speed is free of speed errors. Such a fault check may involve checking fault flag information passed to routine 201 from the EBCM 118 diagnostic routines or processing the detected wheel speed in a local diagnostic routine. A fault in the detected wheel speed at 207 causes routine 201 to proceed to 209, while the absence of a fault in the detected wheel speed causes routine 211 to proceed.At 209, a fault indicator can be set that signals a simultaneous motor speed fault and faults in the detected wheel speed. At 211, the detected wheel speed, which was determined to be good at 207, can be used for controlling various subsystems that use the wheel speed. Both 209 and 211 transition to 235.

[0040] If the motor speed is deemed satisfactory at 205, a synchronization of the motor speed and the wheel speed is performed at 213. Synchronization may be desirable, for example, if different sampling rates are used for the motor speed and the detected wheel speed. According to one embodiment, the motor speed can be synchronized with the detected wheel speed by an interpolation process, e.g., using a pair of time-series samples of the motor speed flanking a given time-series sample of the detected wheel speed. Other synchronization processes, such as upward sampling and downward sampling, can also be used.

[0041] In Fig. Figure 3 shows a simplified graphical representation of a one-dimensional interpolation. Fig. 3. It will be noted that the motor speed (MS) has a higher sampling rate than the detected wheel speed (WS). The motor speed is sampled in one time step (i), and the detected wheel speed is sampled in one time step (j), where ( / ) < (j). It is desirable that the motor speed be synchronized with the detected wheel speed. Thus, synchronized motor speed samples correspond to detected wheel speed samples taken at time steps (j). For example, a synchronized motor speed sample 305 is taken at a sampling time t W (j+1) of the detected wheel speed from motor speed sampling values ​​309 and 311 at motor speed sampling times t M (i+1) or t M(i+2) interpolated. The synchronized motor speed (e.g., 305) can be determined from linear interpolation based on the two flanking motor speed samples, polynomial interpolation requiring additional motor speed samples, interpolation of nearest, earlier, or next values, or any other interpolation technique suitable for the relative sampling rates and expected system behavior. Series of synchronized motor speed samples can be subjected to the same or similar filtering and processing as the acquired wheel speed samples.

[0042] After synchronizing the motor speed and the detected wheel speed, the estimated wheel speed is calculated at 215 based on the synchronized motor speed. The estimated wheel speed can be determined as a function of the mechanical ratio of the transmission that mechanically couples the motor 107 and the wheel 105. The estimated wheel speed based on the motor speed can be referred to as the estimated wheel speed or estimated wheel speed information. To account for certain effects of final drive components, a transfer function based on mechanical dynamic models of the electric drivetrain can be used. Mechanical dynamic models can be used to derive force equilibrium relationships of the electric drivetrain, which includes the motor 107 and the final drive, and more precisely in the torque domain.The wheel assembly can include a tire mounted on a wheel, which is attached to a hub. "Wheel," as it is used, can refer to a wheel assembly as described or to a functional equivalent.

[0043] In Fig. Figure 4 shows a simplified schematic representation of a final drive and this provides the basis for a pair of torque balance relationships that apply to the front final drive. Fig. 1 in relation to the single-engine front axle EDU 111, one of the front wheels 105 and the corresponding drive axle 102 correspond. Based on Fig. Figure 4 schematically depicts the mechanical sections of the front axle EDU 111, which includes the motor MA 107 and the gearbox 109. The effective gearbox output torque (T1) and the effective gearbox output speed (ω1) can be determined from the gearbox ratio and the motor input torque (T). i) and from the motor input speed (ω i ) are determined. Fig. Figure 4 shows a further simplification by reducing the rotating components of the motor MA 107 and the gearbox 107 to a rotational equivalent model 405, which has a rotational equivalent inertia (J e ), which contains the effective transmission output torque (T1) and the effective transmission output speed (ω1). The rotational equivalent inertia (J) e ) can be used in conjunction with the example configuration from Fig. 5 can be represented by the following relationship. Je=i12i22(0.5J2i12+J1)+0.5J2i22+J3

[0044] Fig. Figure 5 schematically represents the rotary replacement model 405 on the gear side, which includes an exemplary combined conventional gear set 505, wherein (g 1-g4) represents the gear set with an input at the simple input gear (g1), an output at the simple output gear (g4), and a combination of intermediate gears (g2) and (g3). The rotational inertia (J1) represents the combined rotational inertia of the motor assembly of the MA 107 motor and the input gear (g1). The rotational inertia (J2) represents the combined rotational inertia of the rotor assembly of the combined intermediate gears (g2) and (g3). Furthermore, the rotational inertia (J3) represents the rotational inertia of the output gear (g4). The ratio of (g1) to (g2) is represented by i1, and the ratio of (g3) to (g4) is represented by i2. Other gear set arrangements have different rotational equivalent model representations and may have a corresponding rotational equivalent inertia, which, as the average person skilled in the art will appreciate, is determined in accordance with the specific arrangement.

[0045] Further based on Fig. Figure 4 schematically depicts the drive axle 102 and the wheel 105. The wheel input torque is represented by (T2) and the wheel speed by (ω2). The drive axle is modeled as an active component containing a torsional spring constant (k), which can be a measured quantity, a torsional damping constant (c), which can be adjusted in practice via empirical correlations of the estimated and measured wheel speeds, the rotation angle at the gearbox output (i.e., at the input end of the drive axle) (θ1), and the rotation angle at the wheel (θ2). Fig. Figure 4 shows a further correspondence for wheel 105 by representing the wheel input torque (T2) as the product of the tangential road force (F) and the wheel radius (R) in a rotational equivalent model 407 on the wheel side, which represents the rotational equivalent inertia (J). w ), the wheel input torque (T2) = (FR) and the wheel speed (ω2).

[0046] From the rotational replacement models (405, 407) and from the drive axle model, a pair of torque equilibrium relationships for the front final drive can be derived. Fig. 1. can be represented as follows: Jeθ¨1=T1−Tf1−k(θ1−θ2)−c(θ˙1−θ˙2) Jwθ¨2=k(θ1−θ2)+c(θ˙1−θ˙2)−FR−Tf2, where a single dot above the term indicates a first derivative and a double dot above indicates a second derivative. Thus, (θ̇1) and (θ̇2) represent the angular velocity on the transmission side and the wheel side, respectively, and (θ̈1) and (θ̈2) represent the angular acceleration on the transmission side and the wheel side, respectively. (T f1 ) represents friction losses on the gearbox side and (T f2) represents friction losses on the wheel side. In the present application, friction losses are assumed to be negligible and are therefore assumed to be zero. Thus, the pair of torque equilibrium relations (2) and (3) can be further simplified to the following torque equilibrium relations: Jeθ¨1=T1−k(θ1−θ2)−c(θ˙1−θ˙2) Jwθ¨2=k(θ1−θ2)+c(θ˙1−θ˙2)−FR. (k(θ1 - θ2)) represents a torsional spring counter-torque of the drive axle 102 and (c(θ̇1 - θ̇2)) represents a torsional damping torque of the drive axle 102. Assuming no slip between the wheel and the road surface and further assuming a horizontal gradient, the tangential road force (F) can follow the relationship F = ηma, where η is the percentage of the total longitudinal force exerted on the axle, m is the vehicle mass, and a is the vehicle longitudinal acceleration. Without wheel slip, the following equivalence is assumed: a = (ωR)' = Rω' = Rθ̈2. Thus, the torque equilibrium relationship (5) can be expressed by substituting F = ηmRθ̈2, FR = ηmR 2 θ̈2 can be written as follows: Jwθ¨2=k(θ1−θ2)+c(θ˙1−θ˙2)−ηmR2θ¨2.

[0047] Thus, after the front final drive was removed Fig.1. The transfer function can be derived on the basis of classical Laplace transforms as follows, based on the pair of torque equilibrium relations shown here: ω2(s)ω1(s)=sθ2(s)sθ1(s)=θ˙2(s)θ˙1(s)=cs+k(Jw+ηmR2)s2+cs+k.

[0048] Since the wheel speed is the desired estimate, and since angular quantities in θ and its derivatives are not actually measured, equation (7) can be simplified to wheel speed (ω2) and gearbox output speed (ω1). Thus, a second-order transfer function solvable for estimating the wheel speed (ω2) is represented as follows: ω2(s)ω1(s)=cs+k(Jw+ηmR2)s2+cs+k.

[0049] After calculating an estimated wheel speed based on the engine speed at 215, various additional diagnostics can be performed on the estimated wheel speed. For example, an erratic diagnostic routine can be executed at 217. At 219, routine 201 passes to 221 if an erratic diagnostic fault is present. At 221, a fault check of the detected wheel speed is performed to determine whether the detected wheel speed information is considered good, e.g., whether the wheel speed sensor 171 and the wiring harness are free of open circuits and short circuits, and whether the detected wheel speed is free of speed errors. Such a fault check may involve checking fault flag information passed from diagnostic routines of the EBCM 118 to routine 201, or processing the detected wheel speed in a local diagnostic routine.A disturbance in the detected wheel speed at 221 causes routine 201 to proceed to 209, while the absence of a disturbance in the detected wheel speed causes the routine to proceed to 211. At 209, a disturbance flag can be set to indicate simultaneous erratic disturbances in both the estimated wheel speed and the detected wheel speed. The detected wheel speed, determined to be good at 221, can be determined at 211 for use in controlling various subsystems that utilize wheel speed information. Both 209 and 211 proceed to 235. At 219, routine 201 proceeds to 223 if no erratic diagnostic disturbance is present. At 223, correlation and other plausibility diagnostics can be performed to determine, for example, that all estimated wheel speeds are consistent and plausible in magnitude and direction. At 225, routine 201 transitions to 227 if a plausibility diagnosis error is present.At 227, a fault check of the detected wheel speed is performed to determine whether the detected wheel speed is considered good, e.g., whether the wheel speed sensor 171 and the wiring harness are free of open circuits and short circuits, and whether the detected wheel speed is free of speed errors. Such a fault check may involve checking fault flag information passed from diagnostic routines of the EBCM 118 to routine 201, or processing the detected wheel speed in a local diagnostic routine. A fault in the detected wheel speed at 227 causes routine 201 to proceed to 209, while no fault in the detected wheel speed causes the routine to proceed to 211. At 209, a fault flag can be set indicating simultaneous faults in the plausibility of the estimated wheel speed and faults in the detected wheel speed.The detected wheel speed, which was determined to be good at 227, can be determined at 211 for use in controlling various subsystems that use wheel speed information. Both 209 and 211 transition to 235. At 225, routine 201 transitions to 229 if no plausibility diagnostic fault is present.

[0050] At 229, a fault check of the detected wheel speed is performed to determine whether the detected wheel speed is considered good, e.g., whether the wheel speed sensor 171 and the wiring harness are free of open circuits and short circuits, and whether the detected wheel speed is free of speed errors. Such a fault check may involve checking fault flag information passed from diagnostic routines of the EBCM 118 to routine 201, or processing the detected wheel speed in a local diagnostic routine. A fault in the detected wheel speed at 229 causes routine 201 to proceed to 231, while no fault in the detected wheel speed causes the routine to proceed to 230.

[0051] If there are no engine speed disturbances at 205, no erratic, plausibility, or other disturbances in the estimated wheel speed at 217, 219, 223, or 225, and the detected wheel speed at 229 is not considered erroneous, routine 201 proceeds to 230. If the vehicle speed is not low, as can be determined, for example, by comparing the estimated or detected wheel speed with a predetermined threshold, the detected wheel speed at 211 can be determined for use in controlling various subsystems that use wheel speed information. If the vehicle speed is low, the estimated wheel speed at 232 can be determined for use in controlling various subsystems that use wheel speed information. Both 211 and 232 proceed to 235.

[0052] If there are no motor speed disturbances at 205, no erratic, plausibility, or other disturbances of the estimated wheel speed at 217, 219, 223, and 225, and the detected wheel speed is considered to be disturbed at 229, then at 231, the estimated wheel speed is determined instead of the erroneous detected wheel speed for use in controlling various subsystems that use wheel speed information. At 233, the system is notified of the replacement of the detected wheel speed with the estimated wheel speed by setting appropriate disturbance tolerance markers that identify a disturbed detected wheel speed and the replacement of the estimated wheel speed.

[0053] Subsequently, at 235, the estimated wheel speed intended for use, the detected wheel speed intended for use, engine speed fault indicators, wheel speed fault indicators, and fault tolerance indicators are output and made available for consumption and use by the various subsystems in their control. Thus, the estimated wheel speed, which is based on engine speed information, can be used wherever wheel speed information can be used. The estimated wheel speed can replace the detected wheel speed, which has been diagnosed as faulty. The estimated wheel speed can also be used instead of the detected wheel speed based on other conditions or considerations. For example, at low vehicle speeds, the estimated wheel speed can be used instead of the detected wheel speed, regardless of the fault status of the detected wheel speed.The estimated or detected wheel speed can be used to control various vehicle subsystems, including the electric propulsion subsystem 103, the suspension subsystem 50, the steering subsystem 60, and the brake subsystem 70. Thus, the electric propulsion subsystem 103 can use the estimated or detected wheel speed at each corner of the vehicle for torque vectoring and electronic differential control. The suspension subsystem 50 can use the estimated or detected wheel speed for roll control, brake dive control, and launch control. The steering subsystem 60 can use the estimated or detected wheel speed during low- and high-speed maneuvers for front- and rear-wheel steering angle control.The brake subsystem 70 can use the estimated or detected wheel speed at each corner of the vehicle for traction control, stability control, and anti-lock braking control.

[0054] It is assumed here that all numerical values, whether explicitly stated or not, are modified by the term "approximately". For the purposes of this disclosure, ranges may be expressed as from "approximately" one particular value to "approximately" another particular value. The term "approximately" generally refers to a range of numerical values ​​that a person skilled in the art would consider equivalent to the stated numerical value, that have the same function or result, or that generally lie reasonably within the manufacturing tolerances of the stated numerical value.

[0055] If a relationship between a first and a second element is not explicitly described as "direct" in the above revelation, this relationship can be a direct relationship in which there are no other intervening elements between the first and the second element, but it can also be an indirect relationship in which there are one or more (either spatially or functionally) intervening elements between the first and the second element.

[0056] It is to be understood that one or more steps within a process can be carried out in a different order (or simultaneously) without altering the principles of this disclosure. Although each of the embodiments above is described as having certain features, any or more of these features described in relation to any embodiment of the disclosure can also be implemented in and / or together with features of any of the other embodiments, even if this combination is not explicitly described. In other words, the described embodiments are not mutually exclusive, and interchanges of one or more embodiments with another remain within the scope of protection of this disclosure.

[0057] Although the above disclosure has been described using exemplary embodiments, those skilled in the art understand that various modifications can be made and equivalents for elements thereof can be substituted without altering its scope of protection. Furthermore, many modifications can be made to adapt a particular situation or material to the teachings of the disclosure without deviating from its essential scope of protection. Thus, the present disclosure is not intended to be limited to the specific disclosed embodiments, but rather to include all embodiments that fall within its scope of protection.

Claims

[1] Device for wheel speed estimation, the device comprising: an electric drive train comprising an electric motor providing motor speed, a wheel, and a mechanical coupling between the motor and the wheel; and an electronic control unit that calculates an estimated wheel speed based on the motor speed and mechanical dynamic models of the electric powertrain. [2] Device according to claim 1, wherein the electronic control unit synchronizes the motor speed with a detected wheel speed. [3] Device according to claim 1, wherein the electronic control unit processes a detected wheel speed. [4] Device according to claim 1, wherein the mechanical coupling between the motor and the wheel comprises a transmission and a drive axle. [5] Device according to claim 4, wherein the mechanical dynamic models of the electric drive train comprise that the drive axle is modeled as an active component which includes a torsional spring constant, a torsional damping constant, a rotation angle at an output of the gearbox and a rotation angle at the wheel. [6] Device according to claim 5, wherein the mechanical dynamic models of the electric drive train further comprise a rotational substitute model of the electric motor and the transmission. [7] Device according to claim 6, wherein the estimated wheel speed is calculated from a second order transfer function derived from the mechanical dynamic models of the electric drive train. [8] Device according to claim 1, wherein the electric motor provides a motor speed, comprising the electric motor providing the motor speed on the basis of a motor speed encoder. [9] Vehicle powered by an electric motor, the vehicle comprising: an electric powertrain that includes: an electric drive unit comprising an electric motor mechanically coupled to an input of a gearbox and a motor controller that provides a motor speed from a rotary encoder; a wheel; and a drive axle that mechanically couples the wheel to an output of the gearbox; and an electronic control unit: which calculates an estimated wheel speed based on the motor speed and mechanical dynamic models of the electric powertrain; the detected wheel speed is processed by a wheel speed sensor; and provides the detected wheel speed and the estimated wheel speed for a vehicle subsystem that is controlled based on the wheel speed information. [10] Vehicle driven by an electric motor according to claim 9, wherein the mechanical dynamic models of the electric powertrain comprise that the drive axle is modeled as an active component which includes a torsional spring constant (k), a torsional damping constant (c), a rotation angle at an output of the gearbox (θ1) and a rotation angle at the wheel (θ2).

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