Motor redundancy control method and control unit for automobile EPS system

Abstract

The invention relates to the technical field of automobile motor control, in particular to a motor redundancy control method for an automobile EPS system and a control unit. The method comprises the steps that torque, a turning angle, a steering direction and a vehicle speed in the vehicle driving process are obtained; according to the change condition of the turning angle in each single steering time period, the possibility that the steering time period is a steering out-of-control-prone time period is obtained, and the steering out-of-control-prone time period and a steering normal time period are determined; according to the vehicle speed change and possibility of the adjacent single-steering time periods in the steering out-of-control-prone time periods, the vehicle speed control capability value of each steering out-of-control-prone time period is obtained; and integrating the torque, the control difficulty degree, the vehicle speed control capability value and the possibility at each moment to obtain a control instruction at each moment, and judging whether to switch different windings in the motor or not according to the control instruction at the current moment to complete motor redundancy control. According to the invention, the timeliness and the stability of motor redundancy control when the automobile runs on various road surfaces are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of automotive motor control, and particularly to a motor redundancy control method and a control unit for an automotive EPS system. Background Art

[0002] An automotive EPS system (Electric Power Steering system) is a steering system that uses an electric motor to provide auxiliary power. It adjusts the assist force of the electric motor according to the vehicle speed and steering torque through an electronic control unit (ECU) to achieve steering. The basic components of the EPS system include a torque sensor, a vehicle speed sensor, an ECU, an assist motor, a reduction mechanism, etc.

[0003] Motor redundancy control is to ensure the operation ability of the system by adding backups or multiple functions of key components to maintain the system's operation through the normal operation of the remaining parts in the event of a single-point failure, thereby avoiding system failure caused by a single-point failure. Motor redundancy control for an automotive EPS system is an important technology to improve vehicle safety, reliability, and driving experience.

[0004] During the process of a vehicle driving on a wet or uneven road surface, when frequently steering or making a sharp turn to avoid an obstacle emergently, higher requirements are put forward for aspects such as the rapidity, steady-state accuracy, and anti-interference ability of motor control. If the motor control is not timely and stable at this time, it is easy to cause difficult steering. And when controlling the vehicle steering, when the control instruction is inaccurate, it is easy to cause the motor to fail to respond to the control instruction in time, and it is easily misjudged that the motor cannot work properly, thus switching to the standby winding, resulting in inaccurate motor redundancy control. Summary of the Invention

[0005] In order to solve the problem of inaccurate motor redundancy control during the process of a vehicle driving on a wet or uneven road surface, the purpose of the present invention is to provide a motor redundancy control method and a control unit for an automotive EPS system, and the specific technical solutions adopted are as follows: In a first aspect, the present invention provides a motor redundancy control method for an automotive EPS system, and the method includes the following steps: Obtain the torque, steering angle, steering direction, and vehicle speed applied by the driver to the steering wheel during the vehicle driving process; Divide the driving process into multiple single-steering time periods based on the steering direction of the steering wheel; according to the change situation of the steering angle in each single-steering time period, obtain the steering out-of-control risk factor of each single-steering time period; according to the steering out-of-control risk factor and quantity of each single-steering time period in each steering period, obtain the possibility that each steering period is an easily out-of-control steering period, and determine the easily out-of-control steering period and the normal steering period; the steering period is obtained by merging single-steering time periods based on the time interval between single-steering time periods; Based on the vehicle speed change situation and the said possibility within the steering out-of-control period for adjacent single-steering time periods, obtain the vehicle speed control ability value for each steering out-of-control period; cluster the moments within the steering out-of-control period into multiple clustering clusters according to the difference in the steering angles at adjacent moments within the steering out-of-control period; obtain the control difficulty level corresponding to each clustering cluster according to the torques of all moments within the clustering cluster; Integrate the torque, control difficulty level, vehicle speed control ability value, and the said possibility for each moment within the clustering cluster, obtain the control instruction for each moment, and determine whether to switch different windings within the motor according to the control instruction at the current moment to complete the redundant control of the motor.

[0006] Preferably, dividing the driving process into multiple single-steering time periods based on the steering direction of the steering wheel includes: consecutive moments with the same steering direction of the steering wheel form a single-steering time period.

[0007] Preferably, obtaining the steering out-of-control risk factor for each single-steering time period according to the change situation of the steering angle within each single-steering time period includes: For any single-steering time period: Calculate the first difference between the steering angles at the first moment and the last moment within the said any single-steering time period; take the ratio of the first difference to the duration of the said any single-steering time period as the steering change rate; take the variance of the steering angle differences at all adjacent moments within the said any single-steering time period as the steering non-smooth factor; Determine the product of the steering change rate and the steering non-smooth factor as the steering out-of-control risk factor for the said any single-steering time period.

[0008] Preferably, the acquisition of the steering period includes: Based on the time interval between every two single-steering time periods, use the K-means clustering algorithm to cluster all single-steering time periods to obtain multiple initial clusters; Take the time period corresponding to each initial cluster as a steering period.

[0009] Preferably, obtaining the possibility that each steering period is a steering out-of-control period according to the steering out-of-control risk factor and quantity of single-steering time periods within each steering period, and determining the steering out-of-control period and the normal steering period includes: For any steering period: Calculate the first ratio between the quantity of single-steering time periods within the said any steering period and the duration of the said any steering period; calculate the sum value of the steering out-of-control risk factors of all single-steering time periods within the said any steering period; Determine the normalized result of the product between the first ratio and the sum value as the possibility that the said any steering period is a steering out-of-control period; If the possibility is greater than a preset possibility threshold, then any one of the steering time periods is taken as an out-of-control steering time period; if the possibility is less than or equal to the preset possibility threshold, then any one of the steering time periods is taken as a normal steering time period.

[0010] Preferably, obtaining the vehicle speed control ability value of each out-of-control steering time period according to the vehicle speed change situation and the possibility within adjacent single-steering time periods in the out-of-control steering time period includes: For any out-of-control steering time period: Taking the product of the average vehicle speed and the vehicle speed variance at all moments within each single-steering time period in any out-of-control steering time period as the instability factor corresponding to the single-steering time period; According to the average value of the instability factors of adjacent two single-steering time periods and the corresponding vehicle speed difference within any out-of-control steering time period, obtaining the vehicle speed instability value of any out-of-control steering time period, and both the average value of the instability factors and the vehicle speed difference are positively correlated with the vehicle speed instability value; Taking the ratio of the vehicle speed instability value of any out-of-control steering time period to the possibility that any out-of-control steering time period is an out-of-control steering time period as the vehicle speed control ability value of any out-of-control steering time period.

[0011] Preferably, clustering the moments within the out-of-control steering time period into multiple clustering clusters according to the difference in the steering angles of adjacent moments within the out-of-control steering time period includes: For any out-of-control steering time period: Taking the difference in the steering angles between each moment and its adjacent next moment within any out-of-control steering time period as the steering change amount of each moment within any out-of-control steering time period; Based on the steering change amount of each moment within any out-of-control steering time period, using the K-means clustering algorithm to cluster all the moments within any out-of-control steering time period to obtain multiple clustering clusters.

[0012] Preferably, obtaining the control difficulty level corresponding to each clustering cluster according to the torques of all the moments within the clustering cluster includes: For any clustering cluster: Taking the ratio of the torque range of all the moments within any clustering cluster to the range of all the moments within any clustering cluster as the control difficulty level corresponding to any clustering cluster.

[0013] Preferably, obtaining the control instruction for each moment by comprehensively considering the torque, control difficulty level, vehicle speed control ability value, and the possibility of each moment within the clustering cluster includes: For any moment in any cluster: calculate the second difference between the torque at the any moment and the standard torque; calculate the first product of the control difficulty level corresponding to the any cluster and the second difference; normalize the ratio of the first product to the vehicle speed control ability value in the steering out-of-control period where the any cluster is located to a preset second interval, and use the normalized value as the steering attention level at the any moment. For the normal steering period: normalize the possibility that each normal steering period is a steering out-of-control period to a preset first interval, and use the normalized value as the steering attention level at all moments within the corresponding normal steering period; wherein, the upper limit value of the preset first interval is less than the lower limit value of the preset second interval. Input the steering attention level, vehicle speed, torque, steering angle of the steering wheel, and steering direction during the vehicle driving process into the fuzzy PID controller in the electronic control unit to output a control instruction.

[0014] In a second aspect, the present invention provides a motor redundancy control unit for an automotive EPS system, and this unit includes: A data acquisition module, configured to obtain the torque, steering angle of the steering wheel, steering direction, and vehicle speed applied by the driver on the steering wheel during the vehicle driving process. A first calculation module, configured to divide the driving process into multiple single steering time periods based on the steering direction of the steering wheel; obtain the steering out-of-control risk factor of each single steering time period according to the change situation of the steering angle within each single steering time period; obtain the possibility that each steering period is a steering out-of-control period according to the steering out-of-control risk factor and quantity of the single steering time periods within each steering period, and determine the steering out-of-control period and the normal steering period; the steering period is obtained by merging the single steering time periods based on the time interval between the single steering time periods. A second calculation module, configured to obtain the vehicle speed control ability value of each steering out-of-control period according to the vehicle speed change situation and the possibility between adjacent single steering time periods within the steering out-of-control period; cluster the moments within the steering out-of-control period into multiple clusters according to the difference in the steering angle between adjacent moments within the steering out-of-control period; obtain the control difficulty level corresponding to each cluster according to the torque of all moments within the cluster. A control module, configured to comprehensively obtain the control instruction at each moment based on the torque, control difficulty level, vehicle speed control ability value, and the possibility of each moment within the cluster, and determine whether to switch different windings in the motor according to the control instruction at the current moment to complete the motor redundancy control.

[0015] The present invention has at least the following beneficial effects: First, according to the change of the steering wheel angle during a single steering time period in the process of vehicle driving, the present invention makes a preliminary evaluation of the risk of steering out of control. According to the steering out-of-control risk factors and quantity distribution in each single steering time period within each steering time period, the possibility that each single steering time period is an easily steering-out-of-control time period is evaluated respectively. Based on the evaluation results, the steering time periods are divided into two categories, namely, easily steering-out-of-control time periods and normal steering time periods. Further, in combination with the vehicle speed change situation in adjacent single steering time periods within the easily steering-out-of-control time period, the possibility that the steering time period is an easily steering-out-of-control time period, and the difference in the steering angle at adjacent moments within the easily steering-out-of-control time period, the vehicle speed control ability and the control difficulty degree are evaluated. Finally, through these evaluation results, the importance of the data or the influence degree on the control target is reflected, the redundant control of the motor of the vehicle EPS system is completed, the overall control accuracy is improved, the controller can better adapt to different road conditions, especially in the case of large system dynamic changes, and the controller is helped to optimize specific performance indicators, such as timeliness, steady-state accuracy or anti-interference ability. By using the method provided by the present invention, accurate control instructions can be obtained, thereby obtaining accurate motor control errors, ensuring the accuracy of the judgment on whether to switch different windings in the motor, improving the accuracy of redundant control, and preventing the wrong switching of the standby winding when the motor is normal. Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required to be used in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings.

[0017] Figure 1 It is a flowchart of the method for motor redundant control of the vehicle EPS system provided by the embodiment of the present invention; Figure 2 It is a structural block diagram of the motor redundant control unit of the vehicle EPS system provided by the embodiment of the present invention. Detailed Embodiments

[0018] In order to further elaborate on the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following will be described in detail the method and control unit for motor redundant control of the vehicle EPS system proposed according to the present invention in combination with the drawings and preferred embodiments as follows.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention belongs.

[0020] The following specifically describes the specific solutions of the motor redundancy control method and control unit provided by the present invention for an automotive EPS system in conjunction with the accompanying drawings.

[0021] Embodiment of the motor redundancy control method for an automotive EPS system: This embodiment proposes a motor redundancy control method for an automotive EPS system. As Figure 1 shown, the motor redundancy control method for an automotive EPS system in this embodiment includes the following steps: Step S1, obtain the torque applied by the driver on the steering wheel, the steering angle of the steering wheel, the steering direction, and the vehicle speed during the vehicle's driving process.

[0022] The main components of an automotive EPS system include: (1) Electric motor: The main power source for providing steering assistance.

[0023] (2) Torque sensor: Detect the magnitude of the torque applied by the driver on the steering wheel.

[0024] (3) Vehicle speed sensor: Measure the driving speed of the vehicle to adjust the magnitude of the assistance.

[0025] (4) Electronic control unit (ECU): According to the signals from the torque sensor and the vehicle speed sensor, calculate the appropriate magnitude of the assistance. That is, the ECU calculates the target assistance current according to the preset assistance characteristic curve, combined with the torque and vehicle speed signals, and thus controls the current of the electric motor.

[0026] (5) Reduction mechanism: Convert the high-speed low-torque of the electric motor into low-speed high-torque to provide effective steering assistance.

[0027] In the automotive EPS system, this embodiment uses a fuzzy PID controller integrated inside the ECU to adjust the output of the motor according to real-time data to achieve precise steering control. Among them, the ECU is a hardware device, usually including a microprocessor, a memory, and other electronic components, which is used to receive input signals from various sensors of the vehicle, perform necessary calculations, and issue control instructions to adjust various systems of the vehicle, such as the engine management system, the braking system, the steering system, etc.

[0028] In terms of motor redundancy control, this embodiment adopts winding redundancy, that is, uses a dual-winding axial magnetic field motor. The inside of the motor is an integrated design with two independent three-phase windings integrated. The circuits of the two windings are completely independent, that is, the two windings are powered by independent inverters. The failure of one group does not affect the other group. Each group of windings corresponds to an independent power converter and controller, forming a redundant channel. When one group of windings fails, the faulty channel can be quickly cut off and switched to the other group of normal windings to continue working.

[0029] The steering angle and direction of the steering wheel are measured in real time using a steering angle sensor. Among them, the range of the steering angle of the steering wheel refers to the maximum angle at which the steering wheel deflects from the center position to one side. In this embodiment, this maximum angle is 540 degrees, with the clockwise direction being positive and the counterclockwise direction being negative. The steering angle range is [-540, 540].

[0030] The main function of the automotive EPS system is to reduce the driving burden and improve driving comfort and safety. That is, through the assistance provided by the motor, the force that the driver needs to apply when steering is greatly reduced, and the EPS system can automatically adjust the assistance according to the vehicle speed, making the steering more stable and safe when driving at high speeds, and more relaxed and flexible when driving at low speeds or parking.

[0031] Therefore, in this embodiment, it is necessary to first screen out the periods during which steering is prone to getting out of control during vehicle driving, because the periods during which steering is prone to getting out of control put more precise requirements on the motor redundancy control of the automotive EPS system. For example: when avoiding obstacles emergently or making sharp turns, when driving on slippery or uneven roads, when driving on narrow roads or in complex road conditions, etc., rapid and frequent steering operations are often required.

[0032] During the driving process of this vehicle, the torque applied by the driver to the steering wheel, the steering angle of the steering wheel, the steering direction, and the vehicle speed are collected from the start to the current moment. The steering direction includes three categories, namely the clockwise direction, the counterclockwise direction, and the non-steering direction. In this embodiment, the collection frequencies of the torque, the steering angle of the steering wheel, the steering direction, and the vehicle speed are all 200 Hz, that is, 200 times are collected per second.

[0033] So far, this embodiment has collected the torque applied by the driver to the steering wheel, the steering angle of the steering wheel, the steering direction of the steering wheel, and the vehicle speed at each moment during the vehicle driving process.

[0034] Step S2: Divide the driving process into multiple single-steering time periods based on the steering direction of the steering wheel; obtain the steering out-of-control risk factor for each single-steering time period according to the change situation of the steering angle within each single-steering time period; obtain the possibility that each steering period is a period prone to steering out of control according to the steering out-of-control risk factor and quantity of each single-steering time period within each steering period, and determine the periods prone to steering out of control and the normal steering periods; the steering period is obtained by merging the single-steering time periods based on the time interval between the single-steering time periods.

[0035] The motor redundancy control for an automotive EPS system is to switch to a spare set of windings in the motor when the response error of the currently used set of windings in the motor to the control command is relatively large. When analyzing the response error of the currently used set of windings in the motor to the control command, if the control command output by the fuzzy PID controller is inaccurate, that is, the change amplitude of the control command is too large or too small within a short period of time, and the change is frequent, this will cause the currently used set of windings in the motor to either overreact or underreact, thus being unable to track the control command in a timely and accurate manner, or causing unnecessary frequent adjustments of the currently used set of windings in the motor. This will increase the response error of the control command when the currently used set of windings in the motor is operating normally, causing the system to incorrectly switch to the spare set of windings in the motor, resulting in inaccurate motor redundancy control. And at this time, even if switched to the spare windings, the inaccurate control command will still cause a relatively large control response error for the spare set of windings in the motor.

[0036] Therefore, in this embodiment, by analyzing the steering attention degree at each moment during the steering easy-to-lose-control period as the real-time weight of the fuzzy PID controller, the accuracy of the control command output by the fuzzy PID controller is improved, preventing a large response error of the control command from occurring when the currently used set of windings in the motor is operating normally, thus avoiding incorrect redundancy control, that is, incorrectly switching to the spare set of windings in the motor.

[0037] In an automotive EPS (Electric Power Steering) system, the situation of difficult steering may be caused by various reasons, such as poor road conditions, tire wear, steering system failure, etc. In this case, the motor redundancy control becomes particularly important because it can ensure that even if there is a problem with the currently used set of windings in the motor, the spare set of windings in the motor can intervene in a timely manner to ensure driving safety. Therefore, when steering is easy to lose control, motor redundancy control, that is, ensuring the accuracy of the switching between the two sets of windings is very important. Therefore, in this embodiment, the steering easy-to-lose-control period is first screened out, and more attention is paid to the control of the motor during this period to prevent the spare set of windings in the motor from failing to intervene in a timely manner when there is a problem with the currently used set of windings in the motor.

[0038] In this embodiment, the steering direction of the steering wheel during the driving process of the vehicle is collected in step S1. Next, this embodiment divides the driving process of the vehicle according to the steering direction of the steering wheel.

[0039] Specifically, consecutive moments with the same steering direction of the steering wheel constitute a single steering time period. Since the data acquisition frequency of the steering direction of the steering wheel is 200 Hz, according to common sense, there is no situation where the steering direction of a single moment is different from that of its adjacent two moments. Therefore, by using the above method, the driving process of the vehicle is divided into multiple single steering time periods.

[0040] Next, this embodiment will be described by taking a single steering time period as an example. For other single steering time periods, the method provided in this embodiment can be used for processing.

[0041] Specifically, for any single steering time period: calculate the absolute value of the difference between the steering angles at the first moment and the last moment within this single steering time period, and use this absolute value as the first difference between the steering angles at the first moment and the last moment within this single steering time period; use the ratio of the first difference to the duration of this single steering time period as the steering change rate. Calculate the absolute value of the difference between the steering angles of each two adjacent moments within this single steering time period respectively, and use this absolute value as the steering angle difference between the corresponding two adjacent moments; calculate the variance of the steering angle differences of all adjacent moments within this single steering time period, and use this variance as the steering non-smoothing factor; determine the product of the steering change rate and the steering non-smoothing factor as the steering out-of-control risk factor for this single steering time period. By using this method, the steering out-of-control risk factor for each single steering time period can be obtained.

[0042] Since the greater the steering change rate in the same direction, it indicates that the driver has made a rapid and large-angle sharp turn in a certain direction. And if the steering change amount of the vehicle cannot be kept similar within a unit time at this time, that is, the greater the above variance, it means that the steering process is not smooth and gradual, but sudden and violent, which may lead to unstable dynamic response of the vehicle and increase the risk of out-of-control.

[0043] Take the time interval between every two single steering time periods as the clustering distance, and use the K-means clustering algorithm to cluster all single steering time periods to obtain multiple clusters, and record the clusters obtained at this time as the initial clusters. All single steering time periods within the same initial cluster are close in time; the K-means clustering algorithm is a prior art and will not be elaborated here too much.

[0044] Take the time period corresponding to each initial cluster as a steering period. The first moment of the steering period is the minimum moment among all single steering time periods within the initial cluster, and the last moment of the steering period is the maximum moment among all single steering time periods within the initial cluster. By using the above method, multiple steering periods are obtained.

[0045] If the number of steering direction changes within a steering period is more, that is, the steering is more frequent, and when the out-of-control risk during a single steering process is greater, the steering period is more likely to be a steering out-of-control prone period.

[0046] For any steering period: Calculate the ratio between the number of single steering time periods within the steering period and the duration of the steering period, and denote this ratio as the first ratio; Calculate the sum value of the steering out-of-control risk factors for all single steering time periods within the steering period; Determine the normalized result of the product between the first ratio and the sum value as the possibility that the steering period is an easily out-of-control steering period. In this embodiment, a formula for the possibility is given, and the possibility that the steering period is an easily out-of-control steering period can be expressed as:

[0047] Wherein, represents the possibility that the steering period is an easily out-of-control steering period, represents the sum value of the steering out-of-control risk factors for all single steering time periods within the steering period, represents the number of single steering time periods within the steering period, represents the duration of the steering period, represents a linear normalization function for normalizing data values to (0, 1).

[0048] represents the first ratio. The larger the first ratio, the more steering direction changes are made within the steering period, that is, the more frequent the steering is. And when the out-of-control risk during a single steering process is greater, the steering period is more likely to be an easily out-of-control steering period.

[0049] If the possibility is greater than the preset possibility threshold, then regard the steering period as an easily out-of-control steering period; if the possibility is less than or equal to the preset possibility threshold, then regard the steering period as a normal steering period. In this embodiment, the preset possibility threshold is 0.6. In specific applications, the implementer can set it according to specific circumstances.

[0050] Using the above method, judge all steering periods, and divide all steering periods into two categories, namely easily out-of-control steering periods and normal steering periods.

[0051] Step S3, obtain the vehicle speed control ability value of each easily out-of-control steering period according to the vehicle speed change situation of adjacent single steering time periods within the easily out-of-control steering period and the possibility; Cluster the moments within the easily out-of-control steering period into multiple clustering clusters according to the difference in the steering angles of adjacent moments; Obtain the control difficulty level corresponding to each clustering cluster according to the torques of all moments within the clustering cluster.

[0052] By analyzing the situations of sharp turns and frequent turns during driving, the steering is easily out of control. It is necessary to further analyze whether the driver's steering operation at each moment during the period of easy steering out of control needs more attention. For example, in the cases of sharp turns, steering during high-speed driving, steering on slippery roads, steering on uneven roads, continuous turns, and steering under fatigue driving, the driver's ability to control the steering wheel stability may decrease; and in the period of easy steering out of control, the greater the degree of decline in the driver's ability to control the steering wheel stability, the more attention should be paid to the data at this moment to ensure the safe control of the vehicle's steering by the vehicle's EPE system.

[0053] Next, this embodiment is described by taking a time period in which steering is prone to out-of-control as an example. The method provided in this embodiment can be used to process other time periods in which steering is prone to out-of-control.

[0054] Specifically, for any period of time when steering is prone to loss of control: The mean vehicle speed at all times in each single turning time period within the period when the steering is prone to out of control and the speed variance at all times in each single turning time period within the period when the steering is prone to out of control are calculated respectively. The larger the speed variance, the more drastic the speed change during this steering process; the product of the mean vehicle speed at all times in each single turning time period within the period when the steering is prone to out of control and the speed variance at all times in the same single turning time period is taken as the instability factor of each single turning time period. Each single turning time period within the period when the steering is prone to out of control has a corresponding instability factor.

[0055] Next, based on the average value of the instability factor of two adjacent single turning time periods in the steering easy-to-out-of-control period and the corresponding vehicle speed difference, the vehicle speed instability value of the steering easy-to-out-of-control period is obtained, and the average value of the instability factor and the vehicle speed difference are positively correlated with the vehicle speed instability value.

[0056] Among them, the positive correlation means that the dependent variable will increase as the independent variable increases, and the dependent variable will decrease as the independent variable decreases. It can be an additive relationship, a multiplicative relationship, etc., which is determined by practical applications.

[0057] In this embodiment, a calculation formula for the vehicle speed instability value is given, and the vehicle speed instability value during the period of easy loss of steering control can be expressed as:

[0058] in, Indicates the unstable value of vehicle speed during the period when the steering is prone to out-of-control. It represents the instability factor of the i-th single steering time period within the steering out-of-control period, It represents the instability factor of the i+1th single steering time period within the steering out-of-control period. is the number of single steering time periods within the steering prone-to-loss-of-control period. represents the average vehicle speed at all times within the i-th single steering time period within the steering prone-to-loss-of-control period. represents the average vehicle speed at all times within the (i + 1)-th single steering time period within the steering prone-to-loss-of-control period. is the absolute value function.

[0059] represents the average of the instability factors between the i-th single steering time period and the (i + 1)-th single steering time period. is used to represent the vehicle speed difference between the i-th single steering time period and the (i + 1)-th single steering time period. The more unstable the vehicle speed during two consecutive steerings, and the greater the vehicle speed difference between consecutive steerings, the greater the speed instability of the steering prone-to-loss-of-control period, that is, the greater the speed instability value of the steering prone-to-loss-of-control period.

[0060] Since when a vehicle is prone to losing control during steering, the magnitude of the vehicle speed will significantly affect the vehicle's stability. During steering, the vehicle generates centrifugal force, which is an outward force that attempts to pull the vehicle out of the turning path. According to the principles of physics, the magnitude of the centrifugal force is proportional to the square of the vehicle speed; this means that the faster the vehicle speed, the greater the centrifugal force. Therefore, when driving at high speed, the vehicle is more likely to lose control due to the large centrifugal force, and if the vehicle suddenly accelerates or decelerates during steering, it will cause a sharp change in the centrifugal force, thereby increasing the risk of vehicle loss of control. Therefore, in the more likely steering prone-to-loss-of-control period, the smaller the speed instability, the stronger the driver's ability to control the vehicle speed stability.

[0061] Based on the above characteristics, the ratio of the speed instability value of the steering prone-to-loss-of-control period to the probability that the steering prone-to-loss-of-control period is a steering prone-to-loss-of-control period is determined as the speed control ability value of the steering prone-to-loss-of-control period.

[0062] By using the above method, the speed control ability value of each steering prone-to-loss-of-control period can be obtained.

[0063] For any turning out-of-control period: Calculate the absolute value of the difference between the steering angles at each moment and the next adjacent moment within the turning out-of-control period. This absolute value represents the difference in steering angles between each moment and the next adjacent moment within the turning out-of-control period, and is used as the steering change amount at each moment within the turning out-of-control period. In this embodiment, the steering change amount at the last moment within the turning out-of-control period is set to be the same as that at the penultimate moment. Based on the steering change amounts at each moment within the turning out-of-control period, use the K-means clustering algorithm to cluster all moments within the turning out-of-control period to obtain multiple clusters. The steering change amounts of all moments within the same cluster are similar, and the steering change amounts of moments in different clusters are quite different. Using the above method, cluster all moments within each turning out-of-control period respectively.

[0064] For any cluster: Calculate the torque range of all moments within the cluster and the range of all moments within the cluster. It should be noted that the range of a moment is the difference between the maximum moment and the minimum moment within the cluster. Take the ratio between the torque range of all moments within the cluster and the range of all moments within the cluster as the control difficulty level corresponding to the cluster. The greater the control difficulty level, it indicates that for steering operations with similar steering change amounts within a short period of time, the driver uses extremely different torques to complete the steering operation, that is, the driver has more difficulty controlling the steering wheel. Using this method, the control difficulty level corresponding to each cluster can be obtained.

[0065] Step S4, comprehensively obtain the control instruction for each moment based on the torque, control difficulty level, vehicle speed control ability value, and the possibility of each moment within the cluster, and determine whether to switch different windings in the motor according to the control instruction at the current moment to complete the motor redundancy control.

[0066] Next, this embodiment will comprehensively consider the torque, control difficulty level, vehicle speed control ability value, and possibility to achieve the redundancy control of the motor of the vehicle EPS system.

[0067] Specifically, for any moment in any cluster: Calculate the absolute value of the difference between the torque at this moment and the standard torque, and denote this absolute value as the second difference. Calculate the product of the control difficulty level corresponding to the cluster and the second difference, and denote this product as the first product. Normalize the ratio of the first product to the vehicle speed control ability value of the turning out-of-control period where the cluster is located to a preset second interval, and use the normalized value as the steering attention level at this moment. The method for obtaining the standard torque is as follows: Take the mode of the torques of all moments within the cluster where this moment is located as the standard torque corresponding to this moment. If there are multiple modes, take the mean of these modes as the standard torque. Using the above method, the steering attention level of each moment within each cluster can be obtained.

[0068] For normal steering periods: Normalize the possibility that each normal steering period is a period with easy loss of steering control to within a preset first interval, and use the normalized value as the steering attention for all moments within the corresponding normal steering period; wherein, the upper limit value of the preset first interval is less than the lower limit value of the preset second interval; in this embodiment, the preset second interval is (0.7, 1], and the preset first interval is (0.5, 0.7].

[0069] In this embodiment, during the period with easy loss of steering control, a higher steering attention is given to the moment when steering is more difficult, so as to ensure the control accuracy of a set of windings being used at this time, prevent false fault judgment, and thus avoid incorrect switching to a set of spare windings in the motor, resulting in inaccurate redundant control.

[0070] Input the steering attention, vehicle speed, torque, steering angle of the steering wheel, and steering direction during the vehicle driving process into the fuzzy PID controller in the electronic control unit, and output a control command (current) to control the current of the motor in the vehicle EPS system. At this time, when the output control command (current) is accurate and reasonable, if the control response error of a set of windings currently being used in the motor is large, it indicates that there is a problem with the set of windings currently being used in the motor, and it is necessary to promptly switch to a set of spare windings in the motor to complete the motor redundant control. Prevent inaccurate control commands from misjudging the set of windings currently being used in the normal motor as abnormal, and thus incorrectly switching the spare windings in the motor.

[0071] The ECU will monitor the response of the set of windings currently being used in the motor through the state feedback of the set of windings currently being used in the motor. Specifically: Use a current sensor to collect the state feedback (current) of the set of windings currently being used in the motor in real time.

[0072] In this embodiment, the preset current threshold is 0.3, and in specific applications, the implementer can set it according to specific circumstances.

[0073] If the normalized value of the absolute value of the difference between the control command (current) output by the fuzzy PID controller at the current moment and the state feedback (current) of the set of windings currently being used in the motor at the current moment is less than the preset current threshold, it is determined that the set of windings currently being used in the motor normally responds to the control command. Otherwise, it is determined that the set of windings currently being used in the motor does not normally respond to the control command, and the ECU will immediately stop sending commands to the set of windings currently being used in the motor and switch the control command to the set of spare windings in the motor.

[0074] Therefore, the method provided in this embodiment ensures the accuracy of the control command output by the fuzzy PID controller, further ensures the accuracy of the judgment on whether a set of windings currently in use in the motor can normally respond to the control command, and thus ensures the effect of redundant control.

[0075] When a set of windings currently in use in the motor can normally respond to the control command, the high-speed and low-torque of the motor is converted into low-speed and high-torque through a reduction mechanism to provide effective steering assistance. When a set of windings currently in use in the motor fails to provide the expected response or feedback within a predetermined time, the ECU will regard it as a fault or abnormal situation. The ECU will immediately stop sending commands to the set of windings currently in use in the motor and switch the control command to a set of spare windings in the motor. After receiving the control command, the set of spare windings in the motor starts to work to provide the required control output (current). After the set of spare windings in the motor takes over the control, the vehicle EPS system will become stable again and continue to execute the fuzzy PID control algorithm to maintain steering control.

[0076] The ECU monitors the response of the set of windings currently in use in the motor through the status feedback (current) of the set of windings currently in use in the motor. When a set of windings currently in use in the motor can normally respond to the control command, the high-speed and low-torque of the motor is converted into low-speed and high-torque through a reduction mechanism to provide effective steering assistance. When a set of windings currently in use in the motor fails to provide the expected response or feedback within a predetermined time, the ECU will regard it as a fault or abnormal situation. The ECU will immediately stop sending commands to the set of windings currently in use in the motor and switch the control command to a set of spare windings in the motor.

[0077] After receiving the control command, the set of spare windings in the motor starts to work to provide the required control output (current). After the set of spare windings in the motor takes over the control, the vehicle EPS system will become stable again and continue to execute the fuzzy PID control algorithm to maintain steering control.

[0078] So far, the method provided in this embodiment realizes the redundant control of the motor of the vehicle EPS system.

[0079] In this embodiment, the risk of steering out of control is initially evaluated based on the change in the steering wheel angle during a single steering time period during vehicle driving. According to the steering out-of-control risk factors and quantity distribution of each single steering time period within each steering time period, the possibility of each single steering time period being an easily steering-out-of-control time period is evaluated respectively. Based on the evaluation results, the steering time periods are divided into two categories, namely, easily steering-out-of-control time periods and normal steering time periods. Further, in combination with the vehicle speed change situation of adjacent single steering time periods within the easily steering-out-of-control time period, the possibility of the steering time period being an easily steering-out-of-control time period, and the difference in the angles at adjacent moments within the easily steering-out-of-control time period, the vehicle speed control ability and the control difficulty level are evaluated. Finally, through these evaluation results, the importance of the data or the influence degree on the control target is reflected, the control of the motor of the vehicle EPS system is completed, the overall control accuracy is improved, the controller can better adapt to different road conditions, especially in the case of large system dynamic changes, and the controller is helped to optimize specific performance indicators, such as rapidity, steady-state accuracy or anti-interference ability.

[0080] Embodiment of the motor redundancy control unit for vehicle EPS system: Refer to Figure 2 , which shows the structural block diagram of the motor redundancy control unit for vehicle EPS system provided by an embodiment of the present invention. The system may include a data acquisition module, a first calculation module, a second calculation module, and a control module.

[0081] Among them, the data acquisition module is used to obtain the torque applied by the driver on the steering wheel, the steering wheel angle, the steering direction, and the vehicle speed during vehicle driving; The first calculation module is used to divide the driving process into multiple single steering time periods based on the steering direction of the steering wheel; obtain the steering out-of-control risk factor of each single steering time period according to the change in the angle within each single steering time period; obtain the possibility of each steering time period being an easily steering-out-of-control time period according to the steering out-of-control risk factors and quantity of the single steering time periods within each steering time period, and determine the easily steering-out-of-control time period and the normal steering time period; the steering time period is obtained by merging the single steering time periods based on the time interval between the single steering time periods; The second calculation module is used to obtain the vehicle speed control ability value of each easily steering-out-of-control time period according to the vehicle speed change situation of adjacent single steering time periods within the easily steering-out-of-control time period and the said possibility; cluster the moments within the easily steering-out-of-control time period into multiple clustering clusters according to the difference in the angles at adjacent moments within the easily steering-out-of-control time period; obtain the corresponding control difficulty level of each clustering cluster according to the torque of all moments within the clustering cluster; A control module, which is configured to comprehensively obtain the torque, control difficulty level, vehicle speed control ability value, and the said possibility at each moment within a clustering cluster, acquire a control instruction for each moment, and determine whether to switch different windings in the motor according to the control instruction at the current moment, so as to complete the redundant control of the motor.

[0082] It should be understood that Figure 2 The structural block diagram and its modules of the motor redundant control unit for an automotive EPS system shown can be implemented in various ways. For example, in some embodiments, the unit and its modules can be implemented through hardware, software, or a combination of software and hardware. Among them, the hardware part can be implemented using dedicated logic; the software part can be stored in a memory and executed by an appropriate instruction execution system, such as a microprocessor or dedicated designed hardware. Those skilled in the art can understand that the above methods and units can be implemented using computer-executable instructions and / or included in processor control code. For example, such code is provided on a carrier medium such as a disk, CD, or DVD-ROM, a programmable memory such as a read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The units and modules of this specification can be implemented not only by hardware circuits such as very large scale integrated circuits or gate arrays, semiconductors such as logic chips and transistors, or programmable hardware devices such as field programmable gate arrays and programmable logic devices, but also by software executed by various types of processors, or by a combination of the above hardware circuits and software (for example, firmware).

[0083] For more details about the above-mentioned various modules, reference can be made to other positions in this specification, and no further elaboration will be provided here.

[0084] In other embodiments, a motor redundant control device for an automotive EPS system is further provided, which includes a memory and a processor. The memory is used to store executable program code, and the processor is used to call and run the executable program code from the memory, so that the device executes the above-mentioned motor redundant control method for an automotive EPS system. This device can specifically be a chip, component, or module. The chip can include a processor and a memory connected thereto; among them, the memory is used to store instructions, and when the processor calls and executes the instructions, the chip can execute the motor redundant control method provided in the above-mentioned embodiments for an automotive EPS system.

[0085] In other embodiments, a computer program product is further provided. When the computer program product runs on a computer, it causes the computer to execute the above-mentioned related steps to implement the motor redundant control method provided in the above-mentioned embodiments for an automotive EPS system.

[0086] In other embodiments, a computer-readable storage medium is further provided, in which computer program code is stored. When the computer program code runs on a computer, the computer is enabled to execute the above-mentioned related method steps to implement the motor redundancy control method for an automotive EPS system provided in the above embodiments.

[0087] Among them, the provided unit, electronic device, computer program product, and computer-readable storage medium are all used to execute the corresponding methods provided above. Therefore, the beneficial effects that can be achieved can refer to the beneficial effects in the corresponding methods provided above, and will not be elaborated here.

[0088] It should be noted that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A motor redundancy control method for an automotive EPS system, characterized in that, The method includes the following steps: Obtain the torque applied by the driver on the steering wheel, the steering angle of the steering wheel, the steering direction, and the vehicle speed during the vehicle driving process; Divide the driving process into multiple single-steering time periods based on the steering direction of the steering wheel; according to the change of the steering angle in each single-steering time period, obtain the steering out-of-control risk factor of each single-steering time period; according to the steering out-of-control risk factor and quantity of the single-steering time periods in each steering period, obtain the possibility that each steering period is an easily steering out-of-control period, and determine the easily steering out-of-control period and the normal steering period; the steering period is obtained by merging the single-steering time periods based on the time interval between the single-steering time periods; According to the vehicle speed change situation and the said possibility of adjacent single-steering time periods in the easily steering out-of-control period, obtain the vehicle speed control ability value of each easily steering out-of-control period; cluster the moments in the easily steering out-of-control period into multiple clustering clusters according to the difference of the steering angles of adjacent moments in the easily steering out-of-control period; obtain the control difficulty degree corresponding to each clustering cluster according to the torque of all moments in the clustering cluster; Comprehensively consider the torque, control difficulty degree, vehicle speed control ability value, and the said possibility of each moment in the clustering cluster, obtain the control instruction of each moment, and judge whether to switch different windings in the motor according to the control instruction of the current moment to complete the motor redundant control.

2. The motor redundancy control method for an automotive EPS system according to claim 1, characterized in that, The step of dividing the driving process into multiple single-steering time periods based on the steering direction of the steering wheel includes: consecutive moments with the same steering direction of the steering wheel form a single-steering time period.

3. The motor redundancy control method for an automotive EPS system according to claim 1, characterized in that, The step of obtaining the steering out-of-control risk factor of each single-steering time period according to the change of the steering angle in each single-steering time period includes: For any single-steering time period: Calculate the first difference between the steering angles of the first moment and the last moment in the said single-steering time period; take the ratio of the first difference to the duration of the said single-steering time period as the steering change rate; take the variance of the steering angle differences of all adjacent moments in the said single-steering time period as the steering non-smooth factor; Determine the product of the steering change rate and the steering non-smooth factor as the steering out-of-control risk factor of the said single-steering time period.

4. The motor redundancy control method for an automotive EPS system according to claim 1, characterized in that, The obtaining of the steering period includes: Based on the time interval between every two single-steering time periods, use the K-means clustering algorithm to cluster all single-steering time periods to obtain multiple initial clusters; Take the time period corresponding to each initial cluster as a steering period.

5. The motor redundancy control method for an automotive EPS system according to claim 1, wherein The step of obtaining the possibility that each steering period is an easily steering out-of-control period according to the steering out-of-control risk factor and quantity of the single-steering time periods in each steering period, and determining the easily steering out-of-control period and the normal steering period includes: For any steering period: Calculate the first ratio between the quantity of single-steering time periods in the said steering period and the duration of the said steering period; calculate the sum value of the steering out-of-control risk factors of all single-steering time periods in the said steering period; Determine the normalized result of the product between the first ratio and the sum value as the possibility that the said steering period is an easily steering out-of-control period; If the possibility is greater than a preset possibility threshold, then use any of the steering time periods as an out-of-control steering time period; if the possibility is less than or equal to the preset possibility threshold, then use any of the steering time periods as a normal steering time period.

6. The motor redundancy control method for an automotive EPS system according to claim 1, wherein Obtaining a vehicle speed control ability value for each out-of-control steering time period according to the vehicle speed change situation and the possibility within adjacent single-steering time periods in the out-of-control steering time period, includes: For any out-of-control steering time period: Use the product of the average vehicle speed and the vehicle speed variance at all moments within each single-steering time period in any out-of-control steering time period as the instability factor corresponding to the single-steering time period; According to the average value of the instability factors of two adjacent single-steering time periods within any out-of-control steering time period and the corresponding vehicle speed difference, obtain the vehicle speed instability value of any out-of-control steering time period, and both the average value of the instability factors and the vehicle speed difference are positively correlated with the vehicle speed instability value; Determine the ratio of the vehicle speed instability value of any out-of-control steering time period to the possibility that any out-of-control steering time period is an out-of-control steering time period as the vehicle speed control ability value of any out-of-control steering time period.

7. The motor redundancy control method for an automotive EPS system according to claim 1, characterized in that Clustering the moments within the out-of-control steering time period into multiple clustering clusters according to the difference in the steering angles of adjacent moments within the out-of-control steering time period, includes: For any out-of-control steering time period: Use the difference in the steering angle between each moment within any out-of-control steering time period and the next adjacent moment as the steering change amount of each moment within any out-of-control steering time period; Based on the steering change amount of each moment within any out-of-control steering time period, use the K-means clustering algorithm to cluster all the moments within any out-of-control steering time period to obtain multiple clustering clusters.

8. The motor redundancy control method for an automotive EPS system according to claim 1, wherein Obtaining the control difficulty level corresponding to each clustering cluster according to the torques of all moments within the clustering cluster, includes: For any clustering cluster: Use the ratio of the torque range of all moments within any clustering cluster to the range of all moments within any clustering cluster as the control difficulty level corresponding to any clustering cluster.

9. The motor redundancy control method for an automotive EPS system according to claim 1, characterized in that Comprehensively considering the torque, control difficulty level, vehicle speed control ability value, and the possibility of each moment within the clustering cluster to obtain a control instruction for each moment, includes: For any moment within any clustering cluster: Calculate the second difference between the torque of any moment and the standard torque; calculate the first product of the control difficulty level corresponding to any clustering cluster and the second difference; normalize the ratio of the first product to the vehicle speed control ability value of the out-of-control steering time period where any clustering cluster is located to a preset second interval, and use the normalized value as the steering attention degree of any moment; For the normal steering time period: Normalize the possibility that each normal steering time period is an out-of-control steering time period to a preset first interval, and use the normalized value as the steering attention degree of all moments within the corresponding normal steering time period; where the upper limit value of the preset first interval is less than the lower limit value of the preset second interval; Input the steering attention degree, vehicle speed, torque, steering angle of the steering wheel, and steering direction during the vehicle driving process into the fuzzy PID controller within the electronic control unit, and output a control instruction.

10. A motor redundancy control unit for an automotive EPS system, the unit being used to implement the method described in claim 1, characterized in that, The unit includes: a data acquisition module for acquiring the torque applied by a driver to a steering wheel, the steering angle of the steering wheel, the steering direction, and the vehicle speed during vehicle driving; a first calculation module for dividing the driving process into multiple single-steering time periods based on the steering direction of the steering wheel; obtaining a steering out-of-control risk factor for each single-steering time period according to the change in the steering angle within each single-steering time period; obtaining the possibility that each steering time period is an easily out-of-control steering time period according to the steering out-of-control risk factor and quantity of the single-steering time periods within each steering time period, and determining an easily out-of-control steering time period and a normal steering time period; the steering time period is obtained by merging single-steering time periods based on the time interval between single-steering time periods; a second calculation module for obtaining a vehicle speed control ability value for each easily out-of-control steering time period according to the vehicle speed change situation and the possibility of adjacent single-steering time periods within the easily out-of-control steering time period; clustering the moments within the easily out-of-control steering time period into multiple clustering clusters according to the difference in the steering angle between adjacent moments within the easily out-of-control steering time period; obtaining the control difficulty level corresponding to each clustering cluster according to the torque of all moments within the clustering cluster; a control module for comprehensively obtaining a control instruction for each moment based on the torque, control difficulty level, vehicle speed control ability value, and the possibility of each moment within the clustering cluster, and determining whether to switch different windings in the motor according to the control instruction of the current moment to complete motor redundancy control.

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