Input shaft control method, electric power steering system, steering control system, and vehicle

Abstract

The application provides an input shaft control method, an electric power steering system, a steering control system and a vehicle. The input shaft control method comprises: in an intelligent driving mode, in response to a steering angle stop instruction, obtaining a time interval between the steering angle stop instruction and a next periodic steering angle instruction; wherein the steering angle stop instruction is sent when it is necessary to change the steering angle and / or angular velocity of the input shaft of the electric power steering system, and the steering angle stop instruction is located between two adjacent periodic steering angle instructions; determining a buffer time according to the time interval and a resonance period of the input shaft; and controlling the angular velocity of the motor of the electric power steering system to decrease to zero within the buffer time, so as to make the angular velocity of the input shaft decrease to zero. The application can avoid collision caused by inertia in the angular velocity switching process, reduce noise and vibration, does not increase friction, does not affect energy consumption and driver's feeling, and improves the riding comfort.

Description

Technical Field

[0001] This application relates to the field of electric power steering technology, and more specifically, to an input shaft control method, an electric power steering system, a steering control system, and a vehicle. Background Technology

[0002] In an electric power steering (EPS) system, under intelligent driving mode, the host computer sends a steering angle request. The electric power steering system's motor drives the rack to move, which in turn rotates the input shaft. If the host computer requests an excessively high frequency of angular velocity changes, uncontrolled collisions will occur between the input shaft teeth and the rack teeth during the angular velocity switching process due to inertia, resulting in noise.

[0003] To address these issues, a common practice is to add a damping rubber ring to the input shaft to prevent vibration. However, the damping rubber ring increases friction on the input shaft, leading to increased motor energy consumption. Furthermore, when switching from intelligent driving mode to manual driving mode, the driver's manual torque input needs to overcome the friction of the damping rubber ring, increasing the driver's workload.

[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] This application provides an input shaft control method, an electric power steering system, a steering control system, and a vehicle, which can avoid collisions caused by inertia during angular velocity switching, reduce noise and vibration, and do not increase friction, affect energy consumption and driver feel, thereby improving driving comfort.

[0006] According to one aspect of this application, an input shaft control method for an electric power steering system is provided, comprising: in an intelligent driving mode, in response to a steering angle stop command, acquiring a time interval between the steering angle stop command and the next periodic steering angle command; wherein the steering angle stop command is sent when it is necessary to change the steering angle and / or angular velocity of the input shaft of the electric power steering system, and the steering angle stop command is located between two adjacent periodic steering angle commands; determining a buffer time based on the time interval and the resonance period of the input shaft; and during the buffer time, controlling the angular velocity of the motor of the electric power steering system to decrease to zero, so that the angular velocity of the input shaft decreases to zero.

[0007] This application utilizes the time window between periodic angular commands to gradually reduce the motor output before the angular velocity switch, so that the angular velocity of the motor and input shaft drops to zero, avoiding gear collisions and mechanical resonance caused by sudden changes in angular velocity. This method does not increase friction, does not affect energy consumption or driver feel, and improves driving comfort.

[0008] In some embodiments, the method further includes: in response to the next periodic rotation angle command, controlling the motor to operate so that the input shaft reaches the target rotation angle and / or target angular velocity indicated by the next periodic rotation angle command.

[0009] With the angular velocity of the motor reduced to zero, the controller of the electric power steering system (hereinafter referred to as the EPS controller) drives the motor to operate according to the next periodic steering angle command, which can realize the smooth continuity of steering action and avoid the impact caused by directly switching from high speed to reverse or different speeds.

[0010] In some embodiments, the time interval is calculated based on the sending period of the periodic cornering instruction and the timestamp of the cornering stop instruction, or the time interval is carried by the cornering stop instruction.

[0011] The sending cycle of the periodic cornering command from the host computer is a standard configuration parameter, which the EPS controller can pre-store or obtain through dynamic learning. Using the fixed sending cycle and the timestamp of the cornering stop command, the EPS controller can accurately calculate the remaining time interval; alternatively, the host computer can carry the desired time interval in the cornering stop command.

[0012] In some embodiments, determining a buffer time based on the time interval and the resonance period includes using the smaller of the time interval and the resonance period as the buffer time.

[0013] By limiting the maximum available time of the deceleration process through time intervals (exceeding the time limit will cause command conflicts) and by limiting the safe duration of the deceleration process through resonance cycles (excessive duration may trigger resonance), we can ensure that the deceleration process of the motor and input shaft does not interfere with subsequent commands or cause resonance.

[0014] In some embodiments, during the buffer time, the angular velocity of the motor is reduced to zero through staged control; wherein the staged control includes at least two stages, and the motor angular velocity deceleration rate in the previous stage is less than the motor angular velocity deceleration rate in the subsequent stage.

[0015] By reducing the deceleration rate in the first stage to be smaller than that in the second stage, a gradual deceleration process is achieved, avoiding excessive initial deceleration that could cause instantaneous shock and noise, and ensuring that the engine stops within the buffer time.

[0016] In some embodiments, the phased control includes: during a time period Internally, the real-time angular velocity W of the motor is controlled. o satisfy: ; within a time period Internally, the real-time angular velocity W of the motor is controlled. o satisfy: Among them, W m t is the angular velocity of the motor at the instant the cornering stop command is received. H The buffer time is mentioned above.

[0017] By using two linear functions, a motor deceleration curve that is simple to calculate, easy to implement, and smooth can be achieved, which can smoothly reduce the angular velocity of the motor and the input shaft to zero.

[0018] In some embodiments, the process of obtaining the resonance period of the input shaft includes: during the testing phase, controlling the motor to output vibration torque at different frequencies in a stepping manner to drive the input shaft to vibrate; detecting the vibration torque amplitude of the input shaft at each frequency, and determining the frequency with the largest vibration torque amplitude as the natural resonance frequency of the input shaft; and calculating the resonance period based on the natural resonance frequency.

[0019] Utilizing the principle of energy amplification during resonance, the frequency with the largest vibration torque amplitude is determined as the natural resonant frequency of the input shaft. This method offers accurate detection, strong anti-interference capabilities, and enables precise offline calibration of the natural resonant frequency. The resonance period is the reciprocal of the natural resonant frequency.

[0020] In some embodiments, the stepping method is: starting from 0Hz, the output frequency is increased in fixed steps, wherein the fixed step is in the range of 2Hz to 6Hz.

[0021] Setting a fixed step size requires balancing test efficiency and frequency resolution to ensure that the resonance peak of the input axis can be captured, while avoiding too many sweep points that would lead to excessive test time, so as to reliably detect the inherent resonance frequency within a limited time.

[0022] According to another aspect of this application, an electric power steering system is provided, comprising: a motor; an input shaft for driving a pinion meshing with a rack to rotate in order to transmit steering force; and a controller configured to perform the method described in any of the above embodiments.

[0023] The electric power steering system of this application, by implementing the above-mentioned input shaft control method, can avoid gear collision during angular velocity switching and does not require the addition of damping rubber rings, thus maintaining the high efficiency and good feel of the electric power steering system.

[0024] According to another aspect of this application, a steering control system is provided, comprising: a host computer configured to: in intelligent driving mode, send periodic steering angle commands at a fixed sending cycle; when it is necessary to change the steering angle and / or angular velocity of the input shaft of the electric power steering system, add a steering angle stop command before the sending time of the next periodic steering angle command; and an electric power steering system controller configured to perform the method as described in any of the above embodiments.

[0025] When it is necessary to change the angle and / or angular velocity of the input shaft of the electric power steering system, the host computer sends a stop command before the next periodic angle command is sent. This does not require changing the original sending cycle or disrupting the original communication timing, making full use of the time window between periodic angle commands. Based on the host computer's instructions, the EPS controller uses the time interval between the stop command and the next periodic angle command (while also considering the input shaft's resonance period) as a buffer time. Through staged control, it stops the motor and input shaft, eliminating gear collisions and mechanical resonance between the rack and input shaft caused by inertia during angular velocity switching.

[0026] According to another aspect of this application, a vehicle is provided that includes the aforementioned electric power steering system, or includes the aforementioned steering control system. The vehicle of this application can achieve quiet and smooth switching of steering angle / steering angular velocity during intelligent driving, improving ride comfort while reducing mechanical wear and maintenance costs of the steering system.

[0027] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and do not limit this application. Attached Figure Description

[0028] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0029] Figure 1 A schematic diagram illustrating the steps of the input shaft control method for an electric power steering system provided in an embodiment of this application; Figure 2 This is a schematic diagram illustrating the steps for obtaining the resonance period of the input shaft as provided in an embodiment of this application. Detailed Implementation

[0030] Exemplary embodiments will now be described more fully with reference to the accompanying drawings. However, these exemplary embodiments can be implemented in many forms and should not be construed as limited to those described herein. Rather, these embodiments are provided to make this application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art.

[0031] The accompanying drawings are merely illustrative of this application and are not necessarily drawn to scale. The same reference numerals in the drawings denote the same or similar parts, and therefore repeated descriptions of them will be omitted. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0032] The process shown in the accompanying drawings is merely illustrative and does not necessarily include all steps. For example, some steps can be broken down, some steps can be combined or partially combined, and the actual execution order may change depending on the actual situation. Furthermore, in the description of this application, unless otherwise expressly specified and limited, the term "connection" should be interpreted broadly, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, or it can be a connection within two components.

[0033] It should be noted that, unless otherwise specified, the embodiments of this application and the features in different embodiments can be combined with each other. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0034] Figure 1 This diagram illustrates the main steps of the input shaft control method for an electric power steering system, refer to... Figure 1 As shown, the input shaft control method for an electric power steering system provided in this application embodiment may include: S110, in intelligent driving mode, in response to a steering angle stop command, obtaining the time interval between the steering angle stop command and the next periodic steering angle command; wherein, the steering angle stop command is sent when it is necessary to change the steering angle and / or angular velocity of the input shaft of the electric power steering system, and the steering angle stop command is located between two adjacent periodic steering angle commands; S120, determining a buffer time based on the time interval and the resonance period of the input shaft; S130, during the buffer time, controlling the angular velocity of the motor of the electric power steering system to decrease to zero, so that the angular velocity of the input shaft decreases to zero.

[0035] The steering angle stop command is sent by the host computer when it needs to change the current state of the electric power steering system, and is used to notify the electric power steering system to stop the current action. Specifically, the host computer controls the action of the electric power steering system by sending periodic steering angle commands that indicate the target steering angle and / or target angular velocity of the input shaft.

[0036] The time interval is the period between the cornering stop command and the arrival of the next periodic cornering command. Its length depends on the sending cycle of the periodic cornering commands from the host computer and the insertion position of the cornering stop command. By obtaining the time interval, a usable time window is provided for the deceleration process of the motor and input shaft, avoiding conflicts between the deceleration process and subsequent periodic cornering commands.

[0037] The resonance period is the reciprocal of the input shaft's natural resonant frequency, which can be obtained through offline testing. The buffer time is determined to ensure that the duration of the deceleration process does not exceed the communication idle period between periodic cornering commands to avoid command conflicts, while also preventing the excitation frequency generated by deceleration from falling into the resonant frequency band.

[0038] This application utilizes the time window between periodic angular commands to gradually reduce the motor output before the angular velocity switch, so that the angular velocity of the motor and input shaft drops to zero, avoiding gear collisions and mechanical resonance caused by sudden changes in angular velocity. This method does not increase friction, does not affect energy consumption or driver feel, and improves driving comfort.

[0039] In some embodiments, the input shaft control method further includes: controlling the motor to operate in response to the next periodic rotation angle command, so that the input shaft reaches the target rotation angle and / or target angular velocity indicated by the next periodic rotation angle command.

[0040] With the angular velocity of the motor reduced to zero, the controller of the electric power steering system (hereinafter referred to as the EPS controller) drives the motor to operate according to the next periodic steering angle command, which can realize the smooth continuity of steering action and avoid the impact caused by directly switching from high speed to reverse or different speeds.

[0041] The target state indicated by the next periodic rotation command can be any of the following: causing the input shaft to continue rotating in the original direction of rotation (e.g., rotating at a different angular velocity), causing the input shaft to rotate in the opposite direction, or causing the input shaft to remain stationary. The host computer and the EPS controller can communicate via a CAN bus.

[0042] In some embodiments, the time interval is calculated based on the sending period of the periodic cornering instruction and the timestamp of the cornering stop instruction, or the time interval is carried by the cornering stop instruction.

[0043] The sending period of the periodic cornering command from the host computer (e.g., 10ms, 20ms, etc.) is a standard configuration parameter, which the EPS controller can pre-store or obtain through dynamic learning. Using the fixed sending period and the timestamp of the cornering stop command, the EPS controller can accurately calculate the remaining time interval; alternatively, the host computer can carry the desired time interval in the cornering stop command.

[0044] In some embodiments, determining the buffer time based on the time interval and the resonance period includes using the smaller of the time interval and the resonance period as the buffer time.

[0045] By limiting the maximum available time of the deceleration process through time intervals (exceeding the time limit will cause command conflicts) and by limiting the safe duration of the deceleration process through resonance cycles (excessive duration may trigger resonance), we can ensure that the deceleration process of the motor and input shaft does not interfere with subsequent commands or cause resonance.

[0046] In other implementations, a weighted average or other nonlinear combination method can be used to determine the buffer time based on the time interval and resonance period. Furthermore, in possible implementations, the determination of the buffer time may also consider factors such as the motor's maximum torque capacity and load inertia.

[0047] In some embodiments, during the buffer time, the angular velocity of the motor is reduced to zero by staged control; wherein the staged control includes at least two stages, and the motor angular velocity reduction rate in the previous stage is less than the motor angular velocity reduction rate in the subsequent stage.

[0048] A torque angle sensor can be installed on the input shaft of an electric power steering system to detect the angular velocity of the input shaft. Based on the fixed transmission ratio of the transmission system (including reduction gears, pinion-rack, etc.) (i.e., the speed ratio between the input shaft and the motor), the angular velocity of the motor can be calculated. Alternatively, in some embodiments, a position sensor (such as a rotary transformer, Hall effect sensor, or photoelectric encoder) can be installed on the motor side to measure the angular velocity of the motor, and the angular velocity of the input shaft can be calculated using the transmission ratio.

[0049] By reducing the deceleration rate in the first stage to be smaller than that in the second stage, a gradual deceleration process is achieved, avoiding excessive initial deceleration that could cause instantaneous shock and noise, and ensuring that the engine stops within the buffer time.

[0050] In some embodiments, phased control includes: during a time period Internally, control the real-time angular velocity W of the motor. o satisfy: ; within a time period Internally, control the real-time angular velocity W of the motor. o satisfy: Among them, Wm t is the angular velocity of the motor at the instant the cornering stop command is received. H This is the buffer time.

[0051] By using two linear functions, a motor deceleration curve that is simple to calculate, easy to implement, and smooth can be achieved, which can smoothly reduce the angular velocity of the motor and the input shaft to zero.

[0052] In other implementations, different segment ratios can be used (e.g., the first segment occupies 1 / 3 of the time, and the second segment occupies 2 / 3 of the time), and the coefficients can be adjusted to ensure that the angular velocity of the motor and input shaft smoothly decreases to zero. The number of stages in the staged control can also be three or more. In addition, the rate change law of each segment is not limited to linear; smooth curves such as cosine or parabola can also be used.

[0053] Figure 2 The steps for obtaining the resonance period are illustrated below. Figure 2 As shown, in some embodiments, the process of obtaining the resonance period of the input shaft includes: S210, during the testing phase, controlling the motor to output vibration torque at different frequencies in a stepping manner to drive the input shaft to vibrate; S220, detecting the vibration torque amplitude of the input shaft at each frequency, and determining the frequency with the largest vibration torque amplitude as the natural resonance frequency of the input shaft; S230, calculating the resonance period based on the natural resonance frequency.

[0054] The testing phase refers to the design and development phase of the electric power steering system or the calibration phase before the vehicle rolls off the production line; it is not a real-time operation phase. The stepping method refers to outputting vibration torque sequentially at fixed frequency intervals. The amplitude of the vibration torque can be measured by a torque sensor (or torque angle sensor), characterizing the input shaft torque fluctuation range and reflecting the vibration intensity. By controlling the motor to output vibration torque at different frequencies in a stepping manner, possible resonance frequency bands can be covered. Since the motor and input shaft are rigidly connected through the transmission system, their vibration frequencies are consistent; therefore, the response of the input shaft directly reflects the system's resonance characteristics.

[0055] Utilizing the principle of energy amplification during resonance, the frequency with the largest vibration torque amplitude is determined as the natural resonant frequency of the input shaft. This method offers accurate detection, strong anti-interference capabilities, and enables precise offline calibration of the natural resonant frequency. The resonant period is the reciprocal of the natural resonant frequency.

[0056] In some embodiments, the stepping method is as follows: starting from 0Hz, the output frequency is increased in fixed steps, wherein the fixed step is in the range of 2Hz to 6Hz.

[0057] The fixed step size setting needs to balance test efficiency and frequency resolution, ensuring that the resonance peak of the input axis can be captured (typically, the half-width of the resonance peak is several hertz to tens of hertz), while avoiding too many frequency sweep points that would lead to excessively long test times, so as to reliably detect the inherent resonant frequency within a limited time. The specific fixed step size can be adjusted according to the vehicle type, for example, 5Hz for passenger cars and 3Hz for commercial vehicles due to their larger inertia, but this is not a limitation.

[0058] In one specific implementation, the resonance period of an electric power steering system during the R&D phase can be obtained through the following process: A test controller (which can be set up separately or integrated with the EPS controller) sends a test command to the EPS, and the EPS enters a frequency sweep mode. Starting from 0Hz, the EPS motor outputs sinusoidal torque with a fixed amplitude in 5Hz steps, driving the input shaft to vibrate. A torque angle sensor detects the vibration torque amplitude of the input shaft in real time and records the amplitude corresponding to each frequency point. After sweeping to a preset upper limit (e.g., 100Hz), all amplitudes are compared, and the frequency f corresponding to the maximum value is taken as the inherent resonance frequency. The resonance period T = 1 / f is calculated and stored in the EPS controller's memory.

[0059] This application also provides an electric power steering system, including: a motor; an input shaft for driving a pinion meshing with a rack to rotate in order to transmit steering force; and a controller configured to perform the method of any of the above embodiments.

[0060] The electric motor, acting as the actuator of the electric power steering system, outputs torque / angular velocity according to the instructions of the EPS controller. The EPS controller can be a standalone electronic control unit (ECU) or integrated into the vehicle's domain controller. The input shaft is connected to the motor via a transmission system, driving a pinion gear to drive a rack and pinion, converting the motor's power into steering force. The rotational inertia of the input shaft directly affects the severity of a collision. This application eliminates inertial energy by reducing the angular velocity of the input shaft to zero before switching angular velocities, thus avoiding gear collisions and mechanical resonance caused by sudden changes in angular velocity.

[0061] The electric power steering system of this application, by implementing the above-mentioned input shaft control method, can avoid gear collision during angular velocity switching and does not require the addition of damping rubber rings, thus maintaining the high efficiency and good feel of the electric power steering system.

[0062] The electric power steering system of this application can include various types of electric power steering systems, such as column-assisted electric power steering (C-EPS), pinion-assisted electric power steering (P-EPS), dual pinion-assisted electric power steering (DP-EPS), and rack-assisted electric power steering (R-EPS). Regardless of the type of electric power steering system used, in intelligent driving mode, when it is necessary to change the angle and / or angular velocity of the input shaft, the host computer first sends an angle stop command. The EPS controller uses the time interval between the angle stop command and the next periodic angle command (while also considering the resonance period of the input shaft) as a buffer time to smoothly reduce the motor angular velocity to zero through staged control. When the motor angular velocity drops to zero, the input shaft stops synchronously through the mechanical transmission relationship between the rack and the input shaft, thereby eliminating gear collisions and mechanical resonance between the rack and the input shaft caused by inertia during angular velocity switching.

[0063] This application embodiment also provides a steering control system, including: a host computer configured to: send periodic steering angle commands at a fixed sending cycle in intelligent driving mode; and, when it is necessary to change the steering angle and / or angular velocity of the input shaft of the electric power steering system, add a steering angle stop command before the sending time of the next periodic steering angle command; and an electric power steering system controller configured to execute the method as described in any of the above embodiments.

[0064] The host computer can be a domain controller of the intelligent driving system, but is not limited to this. In intelligent driving mode, the host computer sends periodic angle commands to the electric power steering system via the CAN bus according to a fixed transmission period (such as 10ms, 20ms, etc.). When it is necessary to change the angle and / or angular velocity of the input shaft of the electric power steering system, the host computer adds a cornering stop command before the transmission time of the next periodic angle command, without changing the original transmission period or disrupting the original communication timing, making full use of the time window between periodic angle commands. The EPS controller, based on the instructions from the host computer, uses the time interval between the cornering stop command and the next periodic angle command (while also considering the resonance period of the input shaft) as a buffer time, and stops the motor and input shaft through staged control, eliminating gear collisions and mechanical resonance between the rack and input shaft caused by inertia during angular velocity switching.

[0065] In one specific implementation, assuming the current input shaft is rotating clockwise at an angular velocity ω1 = 100° / s, the host computer plans to change the angular velocity to ω2 = -80° / s (reverse rotation). To eliminate inertial collisions, the host computer and EPS controller perform the following four steps: First, at a certain time point before the next periodic rotation command is sent, the host computer sends a rotation stop command. The rotation stop command can carry a time interval parameter, or the EPS controller can calculate the time interval t1 based on the known sending period and the timestamp of the rotation stop command. Second, upon receiving the rotation stop command, the EPS controller records the current motor angular velocity W. m (This can be obtained differentially from the motor position sensor), acquiring the time interval t1. The EPS controller then reads the resonant period T from the memory and calculates the buffer time t. H =min(t1, T). The EPS controller further adjusts the buffer time t. H and the current motor angular velocity W m The motor is controlled according to a piecewise linear deceleration curve. First stage ( The real-time angular velocity Wo of the motor is controlled to satisfy: Phase Two ( The real-time angular velocity Wo of the motor is controlled to satisfy: The EPS controller calculates the current Wo in each control cycle (e.g., 1ms) and drives the motor to follow. During this process, the input shaft is rigidly connected to the motor through the transmission system, and the angular velocity decreases synchronously. After a buffer time t... H Afterwards, the motor angular velocity decreases to zero, and the input shaft stops rotating. The third step is that, at the predetermined time for the next cycle, the host computer sends the next periodic rotation angle command, carrying the parameter target angular velocity ω2 = -80° / s. Because t H ≤t1, at this point the motor and input shaft have stopped and are waiting for a new command. And because t H ≤T, the deceleration process does not induce mechanical resonance, achieving high comfort and high reliability steering control in intelligent driving mode. Fourth, the EPS controller receives the next periodic steering angle command and drives the motor to operate according to the command requirements, causing the input shaft to reach the target angular velocity, achieving a smooth transition from the stationary state to the target state.

[0066] If the motor and input shaft have not yet completed their deceleration, and the EPS controller receives a new periodic angle command, the EPS controller can interrupt the deceleration of the motor and input shaft, and replan the acceleration or deceleration based on the new periodic angle command, starting from the current speed of the motor and input shaft, to ensure a smooth transition.

[0067] This application also provides a vehicle that includes the above-described electric power steering system or the above-described steering control system. The vehicle of this application can achieve quiet and smooth switching of steering angle / steering angular velocity during intelligent driving, improving ride comfort while reducing mechanical wear and maintenance costs of the steering system.

[0068] Finally, it should be noted that the above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of this application and should not be construed as limiting the specific implementation of this application to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of this application, and all such modifications or substitutions should be considered within the scope of protection of this application.

Claims

1. A method for controlling the input shaft of an electric power steering system, characterized in that, include: In intelligent driving mode, in response to a cornering stop command, the time interval between the cornering stop command and the next periodic cornering command is obtained; The cornering stop command is sent when it is necessary to change the angle and / or angular velocity of the input shaft of the electric power steering system, and the cornering stop command is located between two adjacent periodic cornering commands; The buffer time is determined based on the time interval and the resonance period of the input shaft; During the buffer time, the angular velocity of the motor controlling the electric power steering system is reduced to zero, so that the angular velocity of the input shaft is reduced to zero.

2. The method according to claim 1, characterized in that, The method further includes: In response to the next periodic rotation angle command, the motor is controlled to operate so that the input shaft reaches the target rotation angle and / or target angular velocity indicated by the next periodic rotation angle command.

3. The method according to claim 1, characterized in that, The time interval is calculated based on the sending period of the periodic cornering command and the timestamp of the cornering stop command, or the time interval is carried by the cornering stop command.

4. The method according to claim 1, characterized in that, Determining the buffer time based on the time interval and the resonance period includes: The smaller of the time interval and the resonance period is used as the buffer time.

5. The method according to claim 1, characterized in that, During the buffer period, the angular velocity of the motor is reduced to zero through staged control. The phased control includes at least two phases, and the motor angular velocity deceleration rate in the previous phase is less than that in the next phase.

6. The method according to claim 5, characterized in that, The phased control includes: In time period Internally, the real-time angular velocity W of the motor is controlled. o satisfy: ； In time period Internally, the real-time angular velocity W of the motor is controlled. o satisfy: ； Among them, W m t is the angular velocity of the motor at the instant the cornering stop command is received. H The buffer time is mentioned above.

7. The method according to any one of claims 1 to 6, characterized in that, The process of obtaining the resonance period of the input shaft includes: During the testing phase, the motor is controlled to output vibration torque at different frequencies in a stepping manner to drive the input shaft to vibrate; The vibration torque amplitude of the input shaft at each frequency is detected, and the frequency with the largest vibration torque amplitude is determined as the natural resonant frequency of the input shaft. The resonance period is calculated based on the inherent resonance frequency.

8. The method according to claim 7, characterized in that, The stepping method is as follows: starting from 0Hz, the output frequency is increased in fixed steps, wherein the fixed step is within the range of 2Hz to 6Hz.

9. An electric power steering system, characterized in that, include: Electric motor; An input shaft, which drives a pinion gear meshing with a rack to rotate in order to transmit steering force; A controller configured to perform the method as described in any one of claims 1 to 8.

10. A steering control system, characterized in that, include: The host computer is configured to send periodic cornering commands at a fixed sending interval in intelligent driving mode. When it is necessary to change the angle and / or angular velocity of the input shaft of the electric power steering system, a stop angle command is added before the next periodic angle command is sent. An electric power steering system controller is configured to perform the method as described in any one of claims 1 to 8.

11. A vehicle, characterized in that, It includes the electric power steering system of claim 9, or the steering control system of claim 10.

Images