Motor redundancy control method and control unit for automobile EPS system

Abstract

The present invention relates to the field of automotive motor control technology, and more specifically to a motor redundancy control method and control unit for an automotive EPS system. The method comprises: obtaining the torque, steering angle, steering direction, and vehicle speed during vehicle travel; determining the likelihood that a steering period is prone to loss of control based on the change in steering angle within each single steering time period, and determining the prone-to-loss-of-control period and normal steering period; obtaining the vehicle speed control capability value for each prone-to-loss-of-control period based on the vehicle speed change and likelihood within adjacent single steering time periods within the prone-to-loss-of-control period; and obtaining a control instruction at each moment by integrating the torque, control difficulty, speed control capability value, and likelihood at each moment. Based on the current control instruction, determining whether to switch between different windings within the motor, thereby completing motor redundancy control. The present invention improves the timeliness and stability of motor redundancy control when the vehicle is traveling on various road surfaces.

Description

Technical Field

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

[0002] An automotive EPS (Electric Power Steering) system uses an electric motor to provide auxiliary power. The electronic control unit (ECU) adjusts the motor's power according to vehicle speed and steering torque, thereby achieving steering. The basic components of an EPS system include a torque sensor, vehicle speed sensor, ECU, power-assisted motor, and reduction gear mechanism.

[0003] Motor redundancy control is achieved by adding backup or multiple functions to key components to ensure that in the event of a single point failure, the system's operating capability can be maintained through the normal operation of the remaining parts, thereby avoiding system failure caused by single point failure. Motor redundancy control used in automotive EPS systems is an important technology to improve vehicle safety, reliability and driving experience.

[0004] When a car is driving on a slippery or uneven road, frequent turns or sharp turns to avoid obstacles in an emergency place higher requirements on the speed, steady-state accuracy and anti-interference ability of the motor control. If the motor control is not stable in time, it will easily cause steering difficulties. In addition, when the car is steering, if the control instructions are not accurate, it will easily cause the motor to be unable to respond to the control instructions in time, and it will be easy to mistakenly judge that the motor cannot work normally, thereby switching the backup winding, resulting in inaccurate motor redundant control. Summary of the Invention

[0005] In order to solve the problem of inaccurate motor redundancy control when a car is driving on slippery or uneven roads, the present invention aims to provide a motor redundancy control method and control unit for an automotive EPS system. The technical solutions adopted are as follows:

[0006] In a first aspect, the present invention provides a motor redundancy control method for an automotive EPS system, the method comprising the following steps:

[0007] Obtain the torque, steering wheel angle, steering direction and vehicle speed applied by the driver on the steering wheel during the vehicle's driving;

[0008] The driving process is divided into a plurality of single-turn time periods based on the steering direction of the steering wheel; a steering loss control risk factor for each single-turn time period is obtained based on the change in the steering angle within each single-turn time period; the likelihood that each turning period is a period prone to steering loss control is obtained based on the steering loss control risk factor and the number of single-turn time periods within each turning period, and the steering loss control period and the normal steering period are determined; the turning period is obtained by merging the single-turn time periods based on the time intervals between the single-turn time periods;

[0009] Based on the vehicle speed changes and the probability of adjacent single-turn time periods within the period of easy loss of steering control, the vehicle speed control capability value for each period of easy loss of steering control is obtained; based on the difference in the turning angles at adjacent moments within the period of easy loss of steering control, the moments within the period of easy loss of steering control are clustered into multiple clusters; based on the torque at all moments within the cluster, the control difficulty corresponding to each cluster is obtained;

[0010] The torque, control difficulty, vehicle speed control capability value and the possibility at each moment in the cluster are comprehensively clustered to obtain the control instruction at each moment. According to the control instruction at the current moment, it is determined whether to switch the different windings in the motor to complete the motor redundant control.

[0011] Preferably, the driving process is divided into a plurality of single-turning time periods based on the steering direction of the steering wheel, including: consecutive moments with the same steering direction of the steering wheel constitute a single-turning time period.

[0012] Preferably, obtaining the steering out-of-control risk factor for each single turning time period according to the change of the turning angle in each single turning time period includes:

[0013] For any single-turn time period:

[0014] Calculating a first difference between the turning angles at the first moment and the last moment in any single turning time period; using the ratio of the first difference to the duration of any single turning time period as the turning change rate; and using the variance of the turning angle differences at all adjacent moments in any single turning time period as the turning non-smoothing factor;

[0015] The product of the steering change rate and the steering non-smoothness factor is determined as the steering loss-of-control risk factor of any single turning time period.

[0016] Preferably, obtaining the steering period includes:

[0017] Based on the time interval between each two single-turn time periods, the K-means clustering algorithm is used to cluster all single-turn time periods to obtain multiple initial clusters;

[0018] The time period corresponding to each initial cluster is regarded as a turning period.

[0019] Preferably, obtaining the possibility that each turning period is a period prone to steering out of control based on the steering out of control risk factor and the number of single turning time periods within each turning period, and determining the period prone to steering out of control and the period of normal steering, comprises:

[0020] For any turning period:

[0021] Calculating a first ratio between the number of single-turn time periods within any one turning period and the duration of any one turning period; calculating a sum of the steering out-of-control risk factors of all single-turn time periods within any one turning period;

[0022] Determine a normalized result of the product of the first ratio and the sum as a probability that any one of the steering periods is a period during which steering is prone to loss of control;

[0023] If the possibility is greater than a preset possibility threshold, any turning period is regarded as a period in which steering is prone to out-of-control; if the possibility is less than or equal to the preset possibility threshold, any turning period is regarded as a period in which steering is normal.

[0024] Preferably, obtaining the vehicle speed control capability value for each steering out-of-control period according to the vehicle speed change in adjacent single-turn time periods within the steering out-of-control period and the possibility includes:

[0025] For any period when steering is prone to loss of control:

[0026] The product of the mean vehicle speed at all moments in each single-turn time period within any one of the turning-out-of-control-prone periods and the vehicle speed variance is used as the instability factor of the corresponding single-turn time period;

[0027] Obtaining a vehicle speed instability value for any of the steering control-prone period based on an average value of instability factors and corresponding vehicle speed differences in two adjacent single-steering time periods within any of the steering control-prone period, wherein both the average value of the instability factors and the vehicle speed difference are positively correlated with the vehicle speed instability value;

[0028] The ratio of the vehicle speed instability value of any steering out-of-control period to the possibility that any steering out-of-control period is a steering out-of-control period is determined as the vehicle speed control capability value of any steering out-of-control period.

[0029] Preferably, clustering the moments in the period of easy steering loss of control into a plurality of clusters according to the difference in the turning angles between adjacent moments in the period of easy steering loss of control comprises:

[0030] For any period when steering is prone to loss of control:

[0031] taking the difference between the steering angle at each moment in any one of the periods of easy loss of steering control and the next adjacent moment as the steering change at each moment in any one of the periods of easy loss of steering control;

[0032] Based on the steering change at each moment in any steering out-of-control period, a K-means clustering algorithm is used to cluster all moments in any steering out-of-control period to obtain multiple clusters.

[0033] Preferably, obtaining the control difficulty corresponding to each cluster according to the torque at all times within the cluster includes:

[0034] For any cluster:

[0035] The ratio of the torque range at all times within any cluster to the torque range at all times of any cluster is used as the control difficulty corresponding to any cluster.

[0036] Preferably, the torque, control difficulty, vehicle speed control capability value and the possibility at each moment in the comprehensive clustering to obtain the control instruction at each moment include:

[0037] For any moment in any cluster: calculating a second difference between the torque at that moment and the standard torque; calculating a first product of the control difficulty corresponding to the cluster and the second difference; normalizing the ratio of the first product to the vehicle speed control capability value during the steering loss-of-control period of the cluster to a preset second interval, and using the normalized value as the steering attention level at that moment;

[0038] For a normal steering period: normalize the probability of each normal steering period being a period prone to steering loss of control to a preset first interval, and use the normalized value as the steering attention level for all moments in the corresponding normal steering period; wherein the upper limit of the preset first interval is less than the lower limit of the preset second interval;

[0039] The steering attention, vehicle speed, torque, steering wheel angle and steering direction during the vehicle's driving process are input into the fuzzy PID controller in the electronic control unit, which outputs control instructions.

[0040] In a second aspect, the present invention provides a motor redundancy control unit for an automotive EPS system, the unit comprising:

[0041] A data acquisition module is used to obtain the torque applied by the driver to the steering wheel, the steering wheel angle, the steering direction and the vehicle speed during the driving process;

[0042] A first calculation module is configured to divide the driving process into a plurality of single-turn time periods based on the steering direction of the steering wheel; obtain a steering loss control risk factor for each single-turn time period based on a change in the steering angle within each single-turn time period; obtain a probability that each turning time period is a period prone to steering loss control based on the steering loss control risk factor and the number of single-turn time periods within each turning time period, and determine a period prone to steering loss control and a period of normal steering; the turning time period is obtained by merging the single-turn time periods based on the time intervals between the single-turn time periods;

[0043] The second calculation module is configured to obtain a vehicle speed control capability value for each period of prone steering loss of control based on the vehicle speed variation and the probability of adjacent single-turn turning time periods within the period of prone steering loss of control; cluster the moments within the period of prone steering loss of control into a plurality of clusters based on the difference in turning angles at adjacent moments within the period of prone steering loss of control; and obtain a control difficulty level corresponding to each cluster based on the torque at all moments within the cluster;

[0044] The control module is used to comprehensively cluster the torque, control difficulty, vehicle speed control capability value and the possibility at each moment, obtain the control instruction at each moment, and determine whether to switch different windings in the motor according to the control instruction at the current moment to complete motor redundant control.

[0045] The present invention has at least the following beneficial effects:

[0046] The present invention first conducts a preliminary evaluation of the steering out-of-control risk based on the change of the steering wheel angle in a single turning time period during the driving process of the automobile, and evaluates the possibility of each single turning time period being a steering out-of-control period based on the steering out-of-control risk factor and the quantity distribution of the single turning time period in each steering time period. Based on the evaluation results, the steering time period is divided into two categories, namely, a steering out-of-control period and a steering normal period. The vehicle speed control ability and the control difficulty are further evaluated in combination with the vehicle speed change of adjacent single turning time periods in the steering out-of-control period, the possibility of the steering period being a steering out-of-control period, and the difference in the angle at adjacent moments in the steering out-of-control period. Finally, these evaluation results are used to reflect the importance of the data or the degree of influence on the control target, complete the redundant control of the motor of the automobile EPS system, improve the overall control accuracy, and enable the controller to better adapt to different road conditions. In particular, when the system dynamic changes are large, the controller is helped to optimize specific performance indicators such as timeliness, steady-state accuracy or anti-interference ability. The method provided by the present invention can obtain precise control instructions, thereby obtaining accurate motor control errors, ensuring the accuracy of the judgment on whether to switch different windings in the motor, thereby improving the accuracy of redundant control and preventing the incorrect switching of the spare winding when the motor is normal. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0048] Figure 1 A flowchart of a motor redundancy control method for an automotive EPS system provided by an embodiment of the present invention;

[0049] Figure 2 This is a structural block diagram of a motor redundancy control unit for an automotive EPS system provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0050] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the motor redundancy control method and control unit for the automobile EPS system proposed in accordance with the present invention are described in detail below in combination with the accompanying drawings and preferred embodiments.

[0051] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0052] The specific scheme of the motor redundancy control method and control unit for an automotive EPS system provided by the present invention will be described in detail below with reference to the accompanying drawings.

[0053] An embodiment of a motor redundancy control method for an automotive EPS system:

[0054] This embodiment proposes a motor redundancy control method for an automotive EPS system, such as Figure 1 As shown, the motor redundancy control method for the automotive EPS system of this embodiment includes the following steps:

[0055] Step S1, obtaining the torque applied by the driver on the steering wheel, the steering wheel angle, the steering direction and the vehicle speed during the driving of the vehicle.

[0056] The main components of the automotive EPS system include:

[0057] (1) Electric motor: the main power source for power steering.

[0058] (2) Torque sensor: detects the torque applied by the driver to the steering wheel.

[0059] (3) Vehicle speed sensor: measures the vehicle's speed to adjust the power assist.

[0060] (4) Electronic Control Unit (ECU): Calculates the appropriate power assist amount based on the signals from the torque sensor and vehicle speed sensor. That is, the ECU calculates the target power assist current based on the preset power assist characteristic curve, combined with the torque and vehicle speed signals, and thus controls the current of the motor.

[0061] (5) Speed reduction mechanism: converts the high speed and low torque of the electric motor into low speed and high torque to provide effective steering assistance.

[0062] In an automotive EPS system, this embodiment uses a fuzzy PID controller integrated within the ECU to adjust the motor output based on real-time data for precise steering control. The ECU is a hardware device typically containing a microprocessor, memory, and other electronic components. It receives input signals from various vehicle sensors, performs necessary calculations, and issues control commands to regulate various vehicle systems, such as the engine management system, braking system, and steering system.

[0063] In terms of motor redundancy control, this embodiment utilizes winding redundancy, namely, a dual-winding axial-field motor. The motor incorporates two independent three-phase windings within an integrated design. The two winding circuits are completely independent, meaning they are powered by separate inverters. A failure in one winding does not affect the other. Each winding set corresponds to an independent power converter and controller, forming redundant channels. If one winding fails, the faulty channel is quickly disconnected, allowing the remaining functioning winding set to continue operating.

[0064] A steering angle sensor is used to measure the steering wheel's angle and direction in real time. The steering wheel's angle range refers to the maximum angle the steering wheel can deflect from its center position to one side. In this embodiment, this maximum angle is 540 degrees. With clockwise being the positive direction and counterclockwise being the negative direction, the steering angle range is [-540, 540].

[0065] The main function of the automobile EPS system is to reduce the driving burden and improve driving comfort and safety. That is, through the power assist provided by the electric motor, the force the driver needs to apply when steering is greatly reduced, and the EPS system can automatically adjust the power assist according to the vehicle speed, making steering more stable and safer when driving at high speeds, and easier and more flexible when driving at low speeds or parking.

[0066] Therefore, this embodiment first identifies the periods during driving when steering is most likely to lose control. This is because these periods place more precise demands on the EPS system's motor redundancy control. For example, rapid and frequent steering operations are often required when urgently avoiding obstacles or making sharp turns, when driving on slippery or uneven roads, or when driving on narrow or complex roads.

[0067] During this driving process, the driver's steering torque, steering wheel angle, steering direction, and vehicle speed are collected from the start to the current moment. Steering directions fall into three categories: clockwise, counterclockwise, and no steering. In this embodiment, the torque, steering wheel angle, steering direction, and vehicle speed are collected at a frequency of 200 Hz, or 200 times per second.

[0068] So far, this embodiment has collected the torque applied by the driver to the steering wheel, the steering wheel angle, the steering direction of the steering wheel and the vehicle speed at each moment during the driving process of the vehicle.

[0069] Step S2, dividing the driving process into multiple single-turn time periods based on the steering direction of the steering wheel; obtaining the steering out-of-control risk factor of each single-turn time period based on the change of the steering angle within each single-turn time period; obtaining the possibility that each steering time period is a steering out-of-control period based on the steering out-of-control risk factor and the number of single-turn time periods within each steering period, and determining the steering out-of-control period and the steering normal period; the steering period is obtained by merging the single-turn time periods based on the time interval between the single-turn time periods.

[0070] Motor redundancy control for automotive EPS systems involves switching to a backup set of windings if the current set of windings in use exhibits significant error in responding to control commands. When analyzing the response error of the current set of windings, if the fuzzy PID controller outputs an inaccurate control command—that is, if the control command changes excessively or inadequately within a short period of time, or if the changes are frequent—then the current set of windings in use may overreact or underreact, preventing it from accurately tracking the control command, or causing unnecessary frequent adjustments to the current set of windings. This can increase the control command response error even when the current set of windings is operating normally, causing the system to mistakenly switch to the backup set of windings, resulting in inaccurate motor redundancy control. Even after switching to the backup set of windings, the inaccurate control command will still result in significant control response errors for the backup set of windings.

[0071] Therefore, in this embodiment, the steering attention at each moment in the period when the steering is prone to out of control is analyzed as the real-time weight of the fuzzy PID controller to improve the accuracy of the control instructions output by the fuzzy PID controller, and prevent the occurrence of large control instruction response errors when a set of windings currently in use in the motor is operating normally, thereby preventing erroneous redundant control, that is, erroneous switching to a set of spare windings in the motor.

[0072] In automotive EPS (Electric Power Steering) systems, steering difficulties can be caused by a variety of factors, including poor road conditions, tire wear, and steering system failures. In these situations, motor redundancy becomes crucial, ensuring that even if a problem occurs with the active motor winding, the backup winding can readily intervene, ensuring driving safety. Therefore, motor redundancy—that is, ensuring the accuracy of switching between the two windings—is crucial when steering is prone to loss of control. Therefore, this embodiment identifies periods of high steering risk and prioritizes motor control during these periods to prevent the backup winding from failing to intervene in the event of a problem with the active motor winding.

[0073] In step S1 , this embodiment collects the steering direction of the steering wheel during the driving process of the vehicle. Next, this embodiment divides the driving process of the vehicle according to the steering direction of the steering wheel.

[0074] Specifically, consecutive moments with the same steering direction constitute a single turning time period. Since the steering direction data acquisition frequency is 200 Hz, it is common sense that there is no situation where the steering direction of a single moment is different from that of its two adjacent moments. Therefore, the above method is used to divide the vehicle driving process into multiple single turning time periods.

[0075] Next, this embodiment is described by taking a single-turn time period as an example. Other single-turn time periods can be processed using the method provided by this embodiment.

[0076] Specifically, for any single-turn period, the following steps are performed: the absolute value of the difference between the turning angles at the first and last moments of the period is calculated, and this absolute value is used as the first difference between the turning angles at the first and last moments of the period; the ratio of the first difference to the duration of the period is used as the steering change rate. The absolute value of the difference between the turning angles at each two adjacent moments in the period is calculated, and this absolute value is used as the turning angle difference between the two adjacent moments; the variance of the turning angle differences across all adjacent moments in the period is calculated, and this variance is used as the steering non-smoothing factor; and the product of the steering change rate and the steering non-smoothing factor is used to determine the steering loss control risk factor for the period. Using this method, a steering loss control risk factor for each single-turn period can be obtained.

[0077] A greater rate of change in steering in the same direction indicates that the driver has made a rapid and sharp turn at a larger angle. Furthermore, if the steering change per unit time cannot remain similar, the greater the variance, the more abrupt and dramatic the steering process is, rather than smooth and gradual. This can lead to unstable dynamic response and increase the risk of loss of control.

[0078] The time interval between each two single-turn time periods is used as the clustering distance, and the K-means clustering algorithm is used to cluster all single-turn time periods to obtain multiple clusters. The cluster obtained at this time is recorded as the initial cluster. All single-turn time periods in the same initial cluster are close in time. The K-means clustering algorithm is an existing technology and will not be described in detail here.

[0079] The time period corresponding to each initial cluster is considered a turning period. The first moment of the turning period is the minimum moment of all single turning periods in the initial cluster, and the last moment of the turning period is the maximum moment of all single turning periods in the initial cluster. Using the above method, multiple turning periods are obtained.

[0080] If the number of steering direction changes within a turning period is greater, that is, the steering is more frequent, and the risk of loss of control during a single turning process is greater, the turning period is more likely to be a period where steering is prone to loss of control.

[0081] For any turning period: calculate the ratio between the number of single turning periods within the turning period and the duration of the turning period, and record this ratio as the first ratio; calculate the sum of the steering loss control risk factors of all single turning periods within the turning period; and determine the probability that the turning period is a period prone to steering loss control by normalizing the product of the first ratio and the sum. In this embodiment, a formula for calculating the probability is given, and the probability that the turning period is a period prone to steering loss control can be expressed as:

[0082]

[0083] in, Indicates the possibility that the steering period is prone to loss of control. It represents the sum of the steering loss of control risk factors of all single steering time periods within the steering period. Indicates the number of single turning time periods within the turning period. Indicates the duration of the steering period, Represents a linear normalization function, which is used to normalize data values to (0, 1).

[0084] It represents the first ratio. The larger the first ratio is, the more steering direction changes are made during the steering period, that is, the more frequent the steering is. Moreover, when the risk of loss of control during a single steering process is greater, the steering period is more likely to be a period where steering is prone to loss of control.

[0085] If the probability is greater than a preset probability threshold, the steering period is considered a period of prone-to-out-of-control steering. If the probability is less than or equal to the preset probability threshold, the steering period is considered a period of normal steering. In this embodiment, the preset probability threshold is 0.6. In specific applications, the implementer can set it according to specific circumstances.

[0086] By using the above method, all steering periods are judged and divided into two categories: steering out-of-control period and steering normal period.

[0087] Step S3, obtaining the vehicle speed control capability value for each period of time when steering is prone to out of control based on the vehicle speed changes in adjacent single-turn time periods within the period of time when steering is prone to out of control and the possibility; clustering the moments within the period of time when steering is prone to out of control into multiple clusters based on the differences in the turning angles at adjacent moments within the period of time; and obtaining the control difficulty corresponding to each cluster based on the torque at all moments within the cluster.

[0088] By analyzing sharp and frequent steering during driving, we identify periods of high risk of steering loss. Further analysis is needed to determine whether the driver's steering operations at each moment within these periods require additional attention. For example, during sharp turns, steering at high speeds, steering on slippery or uneven roads, steering continuously, and steering under fatigue, the driver's ability to maintain stable steering control may decline. The greater the decline in stable steering control during these periods, the more attention the data at that moment requires to ensure the vehicle's EPE system maintains safe steering control.

[0089] Next, this embodiment is described by taking a time period during 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 during which steering is prone to out-of-control.

[0090] Specifically, for any period of time when steering is prone to loss of control:

[0091] The mean vehicle speed at all times in each single-turn time period within the period when steering is prone to out-of-control and the speed variance at all times in each single-turn time period within the period when 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-turn time period within the period when steering is prone to out-of-control and the speed variance at all times in the same single-turn time period is taken as the instability factor of each single-turn time period. Each single-turn time period within the period when steering is prone to out-of-control has a corresponding instability factor.

[0092] Next, based on the average value of the instability factors of two adjacent single-steering time periods within the period when steering is prone to out-of-control and the corresponding vehicle speed difference, the vehicle speed instability value of the period when steering is prone to out-of-control is obtained. The average value of the instability factor and the vehicle speed difference are both positively correlated with the vehicle speed instability value.

[0093] Among them, the positive correlation relationship 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 actual application.

[0094] In this embodiment, a calculation formula for the vehicle speed instability value is given. The vehicle speed instability value during the period of easy loss of steering control can be expressed as:

[0095]

[0096] in, Indicates the unstable speed value 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-turn time periods within the period when the turn is prone to out-of-control, represents the average vehicle speed at all times during the i-th single-turn period in the period when the steering is prone to out-of-control, It represents the average vehicle speed at all times in the i+1th single turning time period during the period when the steering is prone to out-of-control. is the absolute value function.

[0097] represents the average value of the instability factor of the i-th single-turn period and the i+1-th single-turn period, This value represents the speed difference between the i-th single-turn period and the i+1-th single-turn period. The more unstable the speed between two consecutive turns, and the greater the speed difference between consecutive turns, the greater the speed instability during the period prone to loss of control. In other words, the speed instability value for this period is greater.

[0098] Vehicle speed significantly affects vehicle stability, as it can be prone to loss of control during turns. During a turn, the vehicle generates centrifugal force, an outward force that attempts to pull the vehicle out of the turning path. According to the principles of physics, centrifugal force is proportional to the square of vehicle speed; this means that the faster the vehicle, the greater the centrifugal force. Therefore, at high speeds, the vehicle is more likely to lose control due to the greater centrifugal force. Furthermore, sudden acceleration or deceleration during a turn can cause a dramatic change in centrifugal force, increasing the risk of loss of control. Therefore, during periods when loss of control is more likely, the less speed instability there is, indicating a greater ability for the driver to maintain stable speed control.

[0099] Based on the above characteristics, the ratio of the vehicle speed instability value of the steering easy-to-out-control period to the possibility that the steering easy-to-out-control period is the steering easy-to-out-control period is determined as the vehicle speed control ability value of the steering easy-to-out-control period.

[0100] By adopting the above method, the vehicle speed control capability value in each steering out-of-control period can be obtained.

[0101] For any period of time when steering is prone to loss of control, the absolute value of the difference between the steering angle at each moment in the period and the next adjacent moment is calculated. This absolute value represents the difference in steering angle between each moment in the period and the next adjacent moment, and is used as the steering change at each moment in the period. In this embodiment, the steering change at the last moment in the period is set as the steering change at the second-to-last moment. Based on the steering change at each moment in the period, a K-means clustering algorithm is used to cluster all moments in the period to obtain multiple clusters. The steering changes at all moments within the same cluster are similar, while the steering changes at moments in different clusters vary significantly. Using this method, all moments in each period of time when steering is prone to loss of control are clustered.

[0102] For any cluster, the torque range and the range of all moments within the cluster are calculated. The range of moments is the difference between the maximum and minimum moments within the cluster. The ratio of the torque range within the cluster to the range of all moments within the cluster is used as the control difficulty level for the cluster. A greater control difficulty level indicates that the driver used significantly different torques to complete steering maneuvers with similar steering changes within a short period of time, meaning that steering wheel control was more difficult for the driver. This method allows us to determine the control difficulty level for each cluster.

[0103] Step S4, comprehensively clustering the torque, control difficulty, vehicle speed control capability value and the possibility at each moment, obtaining the control instruction at each moment, and determining whether to switch different windings in the motor according to the control instruction at the current moment to complete motor redundant control.

[0104] Next, this embodiment will integrate torque, control difficulty, vehicle speed control capability value and possibility to achieve redundant control of the motor of the automobile EPS system.

[0105] Specifically, for any moment in any cluster, the following methods are used: the absolute value of the difference between the torque at that moment and the standard torque is calculated, and this absolute value is recorded as the second difference; the product of the control difficulty corresponding to the cluster and the second difference is calculated, and this product is recorded as the first product; the ratio of the first product to the vehicle speed control capability value during the steering loss-prone period of the cluster is normalized to within a preset second interval, and the normalized value is used as the steering attention level at that moment. The standard torque is obtained by taking the mode of the torques of all moments in the cluster as the standard torque corresponding to that moment; if there are multiple modes, the mean of these modes is used as the standard torque. Using this method, the steering attention level at each moment in each cluster can be obtained.

[0106] For the normal steering period: the probability of each normal steering period being a period prone to steering loss of control is normalized to a preset first interval, and the normalized value is used as the steering attention level at all moments in 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].

[0107] In this embodiment, during the period when steering is prone to loss of control, higher steering attention is given to the more difficult the moment is, so as to ensure the control accuracy of the set of windings being used at that time and prevent misjudgment of faults, which may lead to erroneous switching to a set of spare windings in the motor, making redundant control inaccurate.

[0108] The fuzzy PID controller within the electronic control unit (ECU) inputs the steering focus, vehicle speed, torque, steering wheel angle, and steering direction during driving. This controller then outputs a control command (current) to control the current in the EPS system's motor. Even if the output control command (current) is accurate and reasonable, if the control response error of the motor's currently active windings is large, this indicates a problem with the motor's active windings and requires prompt switching to the motor's spare windings to achieve motor redundancy. This prevents inaccurate control commands from misidentifying the motor's active windings as abnormal, leading to the incorrect switching to the spare windings.

[0109] The ECU monitors the response of the motor's current windings using the motor's current state feedback. Specifically, a current sensor collects the current state feedback from the motor's current windings in real time.

[0110] In this embodiment, the preset current threshold is 0.3. In specific applications, the implementer can set it according to specific circumstances.

[0111] If the normalized absolute difference between the control command (current) output by the fuzzy PID controller and the state feedback (current) of the motor's currently active windings is less than a preset current threshold, the motor's currently active windings are determined to be responding normally to the control command. Otherwise, the motor's currently active windings are determined to be not responding normally to the control command, and the ECU immediately stops sending commands to the currently active windings and switches control commands to the motor's spare windings.

[0112] Therefore, the method provided by this embodiment ensures the accuracy of the control instructions output by the fuzzy PID controller, and further ensures the accuracy of judging whether a set of windings currently in use in the motor responds normally to the control instructions, thereby ensuring the effect of redundant control.

[0113] When the active motor windings respond normally to control commands, the reduction mechanism converts the motor's high speed, low torque into low speed, high torque, providing effective steering assistance. If the active motor windings fail to provide the expected response or feedback within a predetermined timeframe, the ECU identifies this as a fault or abnormality. The ECU immediately stops sending commands to the active motor windings and switches control to the spare motor windings. Upon receiving the control commands, the spare motor windings begin operating to provide the required control output (current). Once the spare motor windings take over control, the vehicle's EPS system stabilizes and resumes executing the fuzzy-PID control algorithm to maintain steering control.

[0114] The ECU monitors the response of the motor's currently active windings using feedback (current) from their status. When the motor's currently active windings respond normally to control commands, the reduction mechanism converts the motor's high-speed, low-torque output into low-speed, high-torque output, providing effective steering assistance. If the motor's currently active windings fail to provide the expected response or feedback within a predetermined timeframe, the ECU deems this a fault or abnormality. The ECU immediately stops sending commands to the motor's currently active windings and switches control to the motor's standby windings.

[0115] After receiving the control command, the spare set of windings in the motor begins to operate to provide the required control output (current). After the spare set of windings in the motor takes over control, the vehicle's EPS system stabilizes again and continues to execute the fuzzy PID control algorithm to maintain steering control.

[0116] Thus, redundant control of the motor of the automobile EPS system is achieved by using the method provided in this embodiment.

[0117] This embodiment first conducts a preliminary evaluation of the steering loss control risk based on the changes in the steering wheel angle within a single turning period during vehicle driving. Then, based on the steering loss control risk factor and quantity distribution of the single turning period within each steering period, the likelihood of each single turning period being a period prone to steering loss control is evaluated. Based on the evaluation results, the steering periods are divided into two categories: periods prone to steering loss control and normal steering periods. Furthermore, the vehicle speed control capability and control difficulty are evaluated based on the changes in vehicle speed between adjacent single turning periods within the period prone to steering loss control, the likelihood of a steering period being a period prone to steering loss control, and the difference in steering angles at adjacent moments within the period prone to steering loss control. Finally, these evaluation results are used to reflect the importance of the data or the degree of impact on the control target, thereby completing the control of the motor of the vehicle EPS system, improving the overall control accuracy, and enabling the controller to better adapt to different road conditions. In particular, under conditions of large system dynamic changes, the controller is helped to optimize specific performance indicators such as rapidity, steady-state accuracy, or anti-interference capability.

[0118] Example of a motor redundant control unit for an automotive EPS system:

[0119] See Figure 2 , which shows a structural block diagram of a motor redundant control unit for an automotive 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.

[0120] 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 the driving process of the vehicle;

[0121] A first calculation module is configured to divide the driving process into a plurality of single-turn time periods based on the steering direction of the steering wheel; obtain a steering loss control risk factor for each single-turn time period based on a change in the steering angle within each single-turn time period; obtain a probability that each turning time period is a period prone to steering loss control based on the steering loss control risk factor and the number of single-turn time periods within each turning time period, and determine a period prone to steering loss control and a period of normal steering; the turning time period is obtained by merging the single-turn time periods based on the time intervals between the single-turn time periods;

[0122] The second calculation module is configured to obtain a vehicle speed control capability value for each period of prone steering loss of control based on the vehicle speed variation and the probability of adjacent single-turn turning time periods within the period of prone steering loss of control; cluster the moments within the period of prone steering loss of control into a plurality of clusters based on the difference in turning angles at adjacent moments within the period of prone steering loss of control; and obtain a control difficulty level corresponding to each cluster based on the torque at all moments within the cluster;

[0123] The control module is used to comprehensively cluster the torque, control difficulty, vehicle speed control capability value and the possibility at each moment, obtain the control instruction at each moment, and determine whether to switch different windings in the motor according to the control instruction at the current moment to complete motor redundant control.

[0124] It should be understood that Figure 2 The block diagram of the motor redundancy control unit for an automotive EPS system and its modules shown can be implemented in various ways. For example, in some embodiments, the unit and its modules can be implemented using hardware, software, or a combination of software and hardware. The hardware portion can be implemented using dedicated logic, while the software portion can be stored in memory and executed by an appropriate instruction execution system, such as a microprocessor or dedicated hardware. Those skilled in the art will appreciate that the methods and units described above can be implemented using computer-executable instructions and / or contained in processor control code, for example, provided on a carrier medium such as a disk, CD, or DVD-ROM, a programmable memory such as read-only memory (firmware), or a data carrier such as an optical or electronic signal carrier. The units and modules described herein can be implemented not only using hardware circuits such as very large-scale integrated circuits or gate arrays, semiconductors such as logic chips or transistors, or programmable hardware devices such as field-programmable gate arrays or programmable logic devices, but can also be implemented using software executed by various types of processors, or a combination of these hardware circuits and software (e.g., firmware).

[0125] For more details about the above modules, please refer to other places in this manual and will not be repeated here.

[0126] In other embodiments, a motor redundancy control device for an automotive EPS system is provided, comprising a memory and a processor. The memory is configured to store executable program code, and the processor is configured to retrieve and execute the executable program code from the memory, thereby enabling the device to perform the motor redundancy control method for an automotive EPS system described above. The device may be a chip, component, or module. The chip may include a processor and memory connected to the chip. The memory is configured to store instructions. When the processor retrieves and executes the instructions, the chip executes the motor redundancy control method for an automotive EPS system described above.

[0127] In other embodiments, a computer program product is also provided. When the computer program product is run on a computer, the computer is caused to execute the above-mentioned related steps to implement the motor redundancy control method for an automotive EPS system provided in the above-mentioned embodiment.

[0128] In other embodiments, a computer-readable storage medium is also provided, in which a computer program code is stored. When the computer program code is run on a computer, the computer executes the above-mentioned related method steps to implement the motor redundancy control method for an automotive EPS system provided in the above embodiment.

[0129] Among them, the provided units, electronic devices, computer program products, and computer-readable storage media 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 repeated here.

[0130] It should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A motor redundancy control method for an automotive EPS system, characterized in that: The method comprises the following steps: Obtain the torque, steering wheel angle, steering direction and vehicle speed applied by the driver on the steering wheel during the vehicle's driving; The driving process is divided into a plurality of single-turn time periods based on the steering direction of the steering wheel; a steering loss control risk factor for each single-turn time period is obtained based on the change in the steering angle within each single-turn time period; the likelihood that each turning period is a period prone to steering loss control is obtained based on the steering loss control risk factor and the number of single-turn time periods within each turning period, and the steering loss control period and the normal steering period are determined; the turning period is obtained by merging the single-turn time periods based on the time intervals between the single-turn time periods; Based on the vehicle speed changes and the probability of adjacent single-turn time periods within the period of easy loss of steering control, the vehicle speed control capability value for each period of easy loss of steering control is obtained; based on the difference in the turning angles at adjacent moments within the period of easy loss of steering control, the moments within the period of easy loss of steering control are clustered into multiple clusters; based on the torque at all moments within the cluster, the control difficulty corresponding to each cluster is obtained; The torque, control difficulty, vehicle speed control capability value and the possibility at each moment in the cluster are comprehensively clustered to obtain the control instruction at each moment. According to the control instruction at the current moment, it is determined whether to switch the different windings in the motor 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 driving process is divided into a plurality of single-turning time periods based on the steering direction of the steering wheel, including: consecutive moments with the same steering direction of the steering wheel constitute a single-turning time period.

3. The motor redundancy control method for an automotive EPS system according to claim 1, characterized in that: The steering out-of-control risk factor for each single turning time period is obtained based on the change of the turning angle in each single turning time period, including: For any single-turn time period: Calculating a first difference between the turning angles at the first moment and the last moment in any single turning time period; using the ratio of the first difference to the duration of any single turning time period as the turning change rate; and using the variance of the turning angle differences at all adjacent moments in any single turning time period as the turning non-smoothing factor; The product of the steering change rate and the steering non-smoothness factor is determined as the steering loss-of-control risk factor of any single turning time period.

4. The motor redundancy control method for an automotive EPS system according to claim 1, characterized in that: Obtaining the steering period, including: Based on the time interval between each two single-turn time periods, the K-means clustering algorithm is used to cluster all single-turn time periods to obtain multiple initial clusters; The time period corresponding to each initial cluster is regarded as a turning period.

5. The motor redundancy control method for an automotive EPS system according to claim 1, characterized in that: The method of obtaining the possibility that each turning period is a period prone to turning out of control based on the turning out of control risk factor and the number of single turning time periods in each turning period, and determining the period prone to turning out of control and the period of normal turning, includes: For any turning period: Calculating a first ratio between the number of single-turn time periods within any one turning period and the duration of any one turning period; calculating a sum of the steering out-of-control risk factors of all single-turn time periods within any one turning period; Determine a normalized result of the product of the first ratio and the sum as a probability that any one of the steering periods is a period during which steering is prone to loss of control; If the possibility is greater than a preset possibility threshold, any turning period is regarded as a period in which steering is prone to out-of-control; if the possibility is less than or equal to the preset possibility threshold, any turning period is regarded as a period in which steering is normal.

6. The motor redundancy control method for an automotive EPS system according to claim 1, characterized in that: The vehicle speed control capability value for each steering out-of-control period is obtained based on the vehicle speed change in adjacent single-steering time periods within the steering out-of-control period and the possibility, including: For any period when steering is prone to loss of control: The product of the mean vehicle speed at all moments in each single-turn time period within any one of the turning-out-of-control-prone periods and the vehicle speed variance is used as the instability factor of the corresponding single-turn time period; Obtaining a vehicle speed instability value for any of the steering control-prone period based on an average value of instability factors and corresponding vehicle speed differences in two adjacent single-steering time periods within any of the steering control-prone period, wherein both the average value of the instability factors and the vehicle speed difference are positively correlated with the vehicle speed instability value; The ratio of the vehicle speed instability value of any steering out-of-control period to the possibility that any steering out-of-control period is a steering out-of-control period is determined as the vehicle speed control capability value of any steering out-of-control period.

7. The motor redundancy control method for an automotive EPS system according to claim 1, characterized in that: The clustering of moments in the period of easy steering loss of control into a plurality of clusters according to the difference in the turning angles between adjacent moments in the period of easy steering loss of control comprises: For any period when steering is prone to loss of control: taking the difference between the steering angle at each moment in any one of the periods of easy loss of steering control and the next adjacent moment as the steering change at each moment in any one of the periods of easy loss of steering control; Based on the steering change at each moment in any steering out-of-control period, a K-means clustering algorithm is used to cluster all moments in any steering out-of-control period to obtain multiple clusters.

8. The motor redundancy control method for an automotive EPS system according to claim 1, characterized in that: The step of obtaining the control difficulty corresponding to each cluster according to the torque at all moments in the cluster includes: For any cluster: The ratio of the torque range at all times within any cluster to the torque range at all times of any cluster is used as the control difficulty corresponding to any cluster.

9. The motor redundancy control method for an automotive EPS system according to claim 1, characterized in that: The torque, control difficulty, vehicle speed control capability value and the possibility at each moment in the comprehensive cluster are obtained to obtain the control instruction at each moment, including: For any moment in any cluster: calculating a second difference between the torque at that moment and the standard torque; calculating a first product of the control difficulty corresponding to the cluster and the second difference; normalizing the ratio of the first product to the vehicle speed control capability value during the steering loss-of-control period of the cluster to a preset second interval, and using the normalized value as the steering attention level at that moment; For a normal steering period: normalize the probability of each normal steering period being a period prone to steering loss of control to a preset first interval, and use the normalized value as the steering attention level for all moments in the corresponding normal steering period; wherein the upper limit of the preset first interval is less than the lower limit of the preset second interval; The steering attention, vehicle speed, torque, steering wheel angle and steering direction during the vehicle's driving process are input into the fuzzy PID controller in the electronic control unit, which outputs control instructions.

10. A motor redundancy control unit for an automotive EPS system, the unit being used to implement the method of claim 1, characterized in that: This unit includes: A data acquisition module is used to obtain the torque applied by the driver to the steering wheel, the steering wheel angle, the steering direction and the vehicle speed during the driving process; A first calculation module is configured to divide the driving process into a plurality of single-turn time periods based on the steering direction of the steering wheel; obtain a steering loss control risk factor for each single-turn time period based on a change in the steering angle within each single-turn time period; obtain a probability that each turning time period is a period prone to steering loss control based on the steering loss control risk factor and the number of single-turn time periods within each turning time period, and determine a period prone to steering loss control and a period of normal steering; the turning time period is obtained by merging the single-turn time periods based on the time intervals between the single-turn time periods; The second calculation module is configured to obtain a vehicle speed control capability value for each period of prone steering loss of control based on the vehicle speed variation and the probability of adjacent single-turn turning time periods within the period of prone steering loss of control; cluster the moments within the period of prone steering loss of control into a plurality of clusters based on the difference in turning angles at adjacent moments within the period of prone steering loss of control; and obtain a control difficulty level corresponding to each cluster based on the torque at all moments within the cluster; The control module is used to comprehensively cluster the torque, control difficulty, vehicle speed control capability value and the possibility at each moment, obtain the control instruction at each moment, and determine whether to switch different windings in the motor according to the control instruction at the current moment to complete motor redundant control.

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