A method for processing friction characteristics of a steering system and a driving assistance device

Abstract

The disclosed embodiment discloses a method for processing friction characteristics of a steering system and a driving assistance device, the method comprising: calculating the target trajectory of the vehicle according to the identified vehicle driving environment and obtaining a target turning angle; judging whether the steering is in a transition state according to the vehicle driving information and the target turning angle, and obtaining the friction torque when the steering is judged to be in a transition state; calculating the torque required to achieve the target turning angle, adjusting the torque according to the friction torque, and obtaining the adjusted torque; controlling the electric power steering EPS to steer according to the adjusted torque. The disclosed embodiment of the method for processing friction characteristics of the steering system and the driving assistance device can provide accurate steering assistance and improve the driving experience.

Description

Technical Field

[0001] The present disclosure relates to but is not limited to the automotive field, and in particular to a method for processing friction characteristics of a steering system and a driving assistance device. Background Art

[0002] Among the functions of the Advanced Driver Assistance System (ADAS), after the ADAS electronic control unit (ECU) identifies the driving environment, it uses electric power steering (EPS) to achieve steering assistance functions, such as the steering assistance function that can keep the vehicle in the center of the lane, the steering assistance function that controls the vehicle to return to the lane when the vehicle is about to deviate from the lane, and the lane change assistance function.

[0003] The steering assist function can be achieved by sending a torque request signal from the ADAS ECU to the EPS ECU. Figure 1 is a schematic diagram of the structure of a driving assistance device in the related art, such as Figure 1 As shown in the figure, the target angle is obtained after the target trajectory is calculated in the ADAS ECU. After that, the torque required to achieve the target angle is calculated and sent to the EPS ECU, which finally controls the steering wheel to reach the target angle.

[0004] However, due to the friction characteristics of the steering system, the target turning angle cannot be achieved accurately, resulting in some problems in the process of achieving lateral control, such as snaking within the lane and sudden swing of the steering wheel during lane centering control; the correction effect of the function of controlling the vehicle to return to the lane is not good, causing the vehicle to deviate from the lane; the lane change speed under the lane change assist function is sometimes fast and sometimes slow, resulting in a poor driving experience. Summary of the invention

[0005] The embodiment of the present disclosure provides a method for processing friction characteristics of a steering system, comprising:

[0006] The target turning angle is obtained by calculating the target trajectory of the vehicle according to the identified vehicle driving environment;

[0007] Determining whether the steering is in a transition state according to the vehicle driving information and the target turning angle, and obtaining the friction torque when it is determined that the steering is in a transition state;

[0008] Calculating the torque required to achieve the target rotation angle, adjusting the torque according to the friction torque, and obtaining an adjusted torque;

[0009] The electric power steering is controlled to perform steering according to the adjusted torque.

[0010] The embodiment of the present disclosure also provides a driving assistance device, including: a calculation module, a judgment module, a conversion module and an output control module;

[0011] The calculation module is configured to calculate the target trajectory of the vehicle according to the identified vehicle driving environment and then obtain the target turning angle;

[0012] The judgment module is configured to judge whether the steering is in a transition state according to the vehicle driving information and the target turning angle, and obtain the friction torque when it is judged that the steering is in a transition state;

[0013] The conversion module is configured to calculate the torque required to achieve the target rotation angle, and adjust the torque according to the friction torque to obtain an adjusted torque;

[0014] The output control module is configured to control the electric power steering to steer according to the adjusted torque.

[0015] The method for processing friction characteristics of a steering system and the driving assistance device provided by at least one embodiment of the present disclosure have the following beneficial effects compared with the prior art:

[0016] The friction torque obtained when the steering is in a transitional state is used to adjust the torque required to reach the target turning angle, and the adjusted torque is sent to the EPS ECU to control the steering wheel to reach the target turning angle. This can provide precise steering assistance and improve the driving experience.

[0017] Other features and advantages of the present disclosure will be described in the following description, and partly become apparent from the description, or be understood by implementing the present disclosure. Other advantages of the present disclosure can be realized and obtained by the schemes described in the description and the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings are used to provide an understanding of the technical solution of the present disclosure and constitute a part of the specification. Together with the embodiments of the present disclosure, they are used to explain the technical solution of the present disclosure and do not constitute a limitation on the technical solution of the present disclosure.

[0019] Figure 1 It is a structural schematic diagram of a driving assistance device in the related art;

[0020] Figure 2 A flow chart of a method for processing friction characteristics of a steering system provided in an exemplary embodiment of the present disclosure;

[0021] Figure 3 A structural block diagram of an ADAS ECU provided in an embodiment of the present disclosure;

[0022] Figure 4AA schematic diagram of EPS characteristics provided for an exemplary embodiment of the present disclosure;

[0023] Figure 4B A schematic diagram of EPS characteristics provided for another exemplary embodiment of the present disclosure;

[0024] Figure 5 A flow chart of a friction torque learning method in a straight-ahead state provided by an embodiment of the present disclosure;

[0025] Figure 6 A flow chart of a friction torque learning method under a rotation angle reversal state provided by an embodiment of the present disclosure;

[0026] Figure 7 A structural block diagram of a driving assistance system provided by an embodiment of the present disclosure;

[0027] Figure 8 A structural block diagram of a driving environment perception sensor provided in an embodiment of the present disclosure;

[0028] Fig. 9 This is a structural block diagram of a driving assistance device provided in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0029] The present disclosure describes multiple embodiments, but the description is exemplary rather than restrictive, and it is apparent to those skilled in the art that there may be more embodiments and implementations within the scope of the embodiments described in the present disclosure. Although many possible feature combinations are shown in the drawings and discussed in the specific embodiments, many other combinations of the disclosed features are possible. Unless specifically limited, any feature or element of any embodiment may be used in combination with any other feature or element in any other embodiment, or may replace any other feature or element in any other embodiment.

[0030] The present disclosure includes and contemplates combinations of features and elements known to those of ordinary skill in the art. The embodiments, features, and elements disclosed in the present disclosure may also be combined with any conventional features or elements to form a unique invention scheme defined by the claims. Any features or elements of any embodiment may also be combined with features or elements from other invention schemes to form another unique invention scheme defined by the claims. Therefore, it should be understood that any feature shown and / or discussed in the present disclosure may be implemented individually or in any appropriate combination. Therefore, except for the limitations made according to the attached claims and their equivalents, the embodiments are not subject to other limitations. In addition, various modifications and changes may be made within the scope of protection of the attached claims.

[0031] In addition, when describing representative embodiments, the specification may have presented the method and / or process as a specific sequence of steps. However, to the extent that the method or process does not rely on the specific order of the steps described herein, the method or process should not be limited to the steps in the specific order described. As will be appreciated by those of ordinary skill in the art, other orders of steps are also possible. Therefore, the specific order of the steps set forth in the specification should not be interpreted as a limitation to the claims. In addition, the claims for the method and / or process should not be limited to the steps performed in the order written, and those skilled in the art can easily understand that these orders can be changed and still remain within the spirit and scope of the disclosed embodiments.

[0032] Figure 2 A flowchart of a method for processing friction characteristics of a steering system provided by an exemplary embodiment of the present disclosure is shown in FIG. Figure 2 As shown, the method for processing the friction characteristics of the steering system may include: S201, S202, S203 and S204.

[0033] S201: Calculating a target trajectory of the vehicle based on the identified vehicle driving environment and obtaining a target turning angle.

[0034] The execution subject of the embodiment of the present disclosure may be an electronic control unit (ECU) of a driving assistance system (Advanced Driver Assistance System, ADAS).

[0035] Figure 3 The structural block diagram of the ADAS ECU provided in the embodiment of the present disclosure is as follows: Figure 3 As shown, the ADAS ECU can calculate the target trajectory of the vehicle based on the results recognized by the camera sensor 108, and then calculate the target turning angle based on the target trajectory. The implementation principle of the ADAS ECU calculating the target trajectory of the vehicle based on the results recognized by the camera sensor and calculating the target turning angle based on the target trajectory is the same as that of the existing solution, and this embodiment will not be limited or elaborated here.

[0036] Due to the friction characteristics of the steering system, the target turning angle cannot be achieved accurately, resulting in some problems in the process of achieving lateral control. Figure 4A A schematic diagram of EPS characteristics provided by an exemplary embodiment of the present disclosure, such as Figure 4A As shown in the figure, due to its friction characteristics, the vehicle motion (Yaw Rate) is not completely consistent with the steering torque, and there is a nonlinear region. Among them, the vehicle motion can be represented by the rotation rate YR.

[0037] S202: Determine whether the steering is in a transition state according to the vehicle driving information and the target turning angle, and obtain the friction torque when it is determined that the steering is in a transition state.

[0038] The influence of friction characteristics can be compensated by increasing the friction torque during the steering control process. The friction characteristics of the steering system only occur in the transition state. The transition state refers to the state from the steering center position to the moment of starting steering, or switching from left to right or from right to left.

[0039] The transition state may be determined by vehicle driving information (such as vehicle speed and / or steering wheel angle) and a target angle. Determining whether the steering is in a transition state based on the vehicle driving information and the target angle may include:

[0040] Compare the actual steering wheel angle of the vehicle with the target angle; when the target angle is inconsistent with the actual steering wheel angle and the change of the target angle meets the set angle change condition, judge that the steering is in a transition state; the set angle change condition includes at least one of the following: the target angle continues to remain unchanged in the median for a certain period of time, the target angle changes from increasing to decreasing, and the target angle changes from decreasing to increasing.

[0041] The transition state judgment method may be: when the target angle remains unchanged at the median (0 degrees) for a certain period of time, for example, when the target angle changes after 0.5 seconds, the state within the time period is defined as the transition state.

[0042] Alternatively, a state in which the target rotation angle changes from increasing to decreasing, or a state in which the target rotation angle changes from decreasing to increasing may be defined as a transition state.

[0043] In one example, after the target angle is consistent with the actual steering wheel angle, or the target angle changes in a direction opposite to the actual steering wheel angle, it is determined that the steering is in a non-transition state.

[0044] When the target angle is consistent with the actual steering wheel angle, or the target angle changes in the opposite direction, the transition state ends. The target angle is consistent with the actual steering wheel angle, which means that the target angle and the actual steering wheel angle are in the same direction, and the angle difference between the target angle and the actual steering wheel angle is within the set range. The target angle is inconsistent with the actual steering wheel angle, which means that the target angle and the actual steering wheel angle are in different directions (excluding the target angle changing in the opposite direction of the actual steering wheel angle), or the angle difference between the target angle and the actual steering wheel angle exceeds the set range.

[0045] When it is determined that the steering is in a transition state, the friction torque is obtained. Obtaining the friction torque may include:

[0046] The set friction torque is obtained; or the friction torque obtained by self-learning the friction characteristics during driving is obtained.

[0047] In one example, the set friction torque can be stored in the ADAS ECU in advance. When it is determined that the steering is in a transitional state, the stored set friction torque is directly obtained to adjust the torque required to achieve the target turning angle, thereby providing precise steering assistance. The set friction torque can be obtained through real vehicle data or simulation data measured in advance.

[0048] In one example, the friction characteristics can be self-learned during driving. When it is determined that the steering is in a transitional state, the self-learned friction torque is obtained and the torque required to reach the target turning angle is adjusted, thereby providing precise steering assistance.

[0049] Figure 4B A schematic diagram of EPS characteristics provided for another exemplary embodiment of the present disclosure is shown in FIG. Figure 4B As shown in the figure, since the friction characteristics are greatly affected by the temperature, vehicle weight, tire characteristics, etc., the vehicle motion is not completely consistent with the actual driver steering torque, and there is a nonlinear area. The driver steering torque is the torque input by the driver on the steering wheel, and the driver steering torque can be called the steering operation torque.

[0050] The disclosed embodiment can self-learn the friction characteristics during driving, provide accurate steering assistance regardless of the state, and can achieve automatic matching, thereby shortening development time and reducing development costs.

[0051] S203: Calculate the torque required to achieve the target rotation angle, adjust the torque according to the friction torque, and obtain the adjusted torque. The torque determined by the target rotation angle can be called the requested torque.

[0052] The disclosed embodiment calculates the torque required to achieve the target turning angle, and does not send the torque to the EPS ECU. Instead, the torque is adjusted by the friction torque when the steering is in a transitional state, and the adjusted torque is sent to the EPS ECU to control the steering wheel to reach the target turning angle, thereby providing precise steering assistance and improving the driving experience.

[0053] In one example, calculating the torque required to reach a target turning angle may include: performing feedback control on the target turning angle, and performing feedforward control on the target turning angle when the steering is in a transition state; and calculating the torque required to reach the target turning angle based on the angle after feedback control and feedforward control.

[0054] In the prior art, compensation for friction characteristics is generally achieved by feedforward control when calculating the requested torque based on the target angle. However, feedforward control does not distinguish between normal and transitional states. If feedforward control parameters are defined based on the transitional state, the feedforward control will be too large in the normal state. On the contrary, if feedforward control parameters are defined based on the normal state, the feedforward control will be too small in the transitional state.

[0055] The disclosed embodiment compensates for the friction characteristics in the transition state, which can significantly improve the vehicle control accuracy. The feedforward control can adjust the feedforward gain according to the transition state determination result. The feedback control can adjust the feedback control gain according to the difference between the target angle and the current steering wheel angle. The sum of the angles after the feedforward control and the feedback control is the target angle.

[0056] In one example, adjusting the torque according to the friction torque to obtain the adjusted torque may include: adding the friction torque and the torque to obtain the adjusted torque, wherein the torque addition is vector addition of the torque.

[0057] When the steering is in a transitional state, the angles calculated based on the feedforward control and feedback control are added and converted into torque, which is then added to the friction torque to obtain the final requested torque which is sent to the EPS ECU.

[0058] S204: Control the electric power steering to steer according to the adjusted torque.

[0059] The ADAS ECU sends a torque request to the EPS ECU to implement the steering assist function. The specific implementation principle is the same as that of the existing solution, and this embodiment will not be limited or elaborated herein.

[0060] The method for processing the friction characteristics of the steering system provided in the embodiment of the present disclosure adjusts the torque required to achieve the target turning angle through the friction torque obtained when the steering is in a transitional state, sends the adjusted torque to the EPS ECU, controls the steering wheel to reach the target turning angle, and can provide precise steering assistance and improve the driving experience.

[0061] In an example embodiment of the present disclosure, the friction characteristics can be self-learned during driving to obtain the friction torque, including: obtaining the current driving state of the vehicle during driving, and when the current driving state of the vehicle meets the set conditions, calculating and storing the friction torque.

[0062] Whether to perform self-learning on the friction characteristics can be determined by judging the current driving state of the vehicle.

[0063] In one example, the current driving state of the vehicle satisfies a set condition, which may include: the current driving state of the vehicle is a straight driving state.

[0064] The friction torque can be self-learned in the straight-ahead state. The friction torque self-learned in the straight-ahead state is the friction torque when the steering wheel starts to turn from the neutral state. When the vehicle is in the straight-ahead state, the steering wheel does not turn significantly, and the vehicle is not likely to deflect significantly. At this time, the friction torque self-learning can prevent the friction characteristics from being affected by the temperature, vehicle weight or tire characteristics.

[0065] In one example, the current driving state of the vehicle satisfies the set condition, which may include: the current driving state of the vehicle is a corner reversal state, wherein the corner reversal means that the steering wheel angle is reversing.

[0066] The friction torque self-learning can be performed in the state of corner reversal. When the vehicle is in the state of corner reversal, the driver usually operates the steering wheel. At this time, the friction torque self-learning can prevent the friction characteristics from being affected by the temperature, vehicle weight or tire characteristics.

[0067] Figure 5 The flowchart of the friction torque learning method in the straight-ahead state provided by the embodiment of the present disclosure is as follows: Figure 5 As shown, the friction torque learning method in the straight-ahead state may include:

[0068] S501: Determine whether the straight-ahead status bit is on. If yes, execute S505; otherwise, execute S502.

[0069] The straight-ahead state bit is an expression of the signal level. The straight-ahead state bit is ON, indicating that the current vehicle is in a straight-ahead state. The straight-ahead state bit is OFF, indicating that the current vehicle is not in a straight-ahead state.

[0070] In one example, the straight state bit can be set to binary "1" (or "0") to indicate that the straight state bit is ON, and the straight state bit can be set to binary "0" (or "1") to indicate that the straight state bit is OFF.

[0071] S502: Determine whether the steering wheel angle is less than 5 degrees. If so, execute S503; otherwise, execute S509.

[0072] A small steering wheel angle indicates that the steering wheel has not turned or has just begun to turn.

[0073] S503: Determine whether the vehicle's rotation rate YR is less than 0.15 degrees / second. If so, execute S504; otherwise, execute S509.

[0074] The vehicle's rotation rate YR is small, indicating that the vehicle does not show significant deflection.

[0075] S504: Set the straight-ahead status bit to ON.

[0076] Whether the straight-ahead state bit is ON can be determined through S502 and S503, wherein S502 and S503 are performed in no particular order.

[0077] The vehicle's running state satisfies the steering wheel angle < 5 degrees and the vehicle's rotation rate YR < 0.15 degrees / second. The vehicle is judged to be in a straight-ahead state, and the straight-ahead state bit becomes ON.

[0078] S505: Determine whether the vehicle's rotation rate YR>0.2 degrees / second. If so, execute S506; otherwise, execute S509.

[0079] The vehicle's rotation rate YR is greater than a set first rate threshold, which may be 0.2±0.05 degrees / second. For example, YR>0.2 degrees / second indicates that a slight change has occurred in the vehicle body.

[0080] If the vehicle's rotation rate YR is less than or equal to the set first rate threshold (for example, YR≤0.2 degrees / second), it means that the vehicle has no obvious body changes and the next judgment cycle needs to be started. In the next judgment cycle, it is first determined whether the vehicle is in a straight-moving state.

[0081] S506: Determine whether the rotation rate of the steering wheel is less than 10 degrees / second. If so, execute S507; otherwise, execute S509.

[0082] The steering wheel rotation rate (also referred to as the angular rate) is less than the set second rate threshold, which may be 10±0.5 degrees / second. For example, if the angular rate is less than 10 degrees / second, it indicates that the angular rate is small and the current steering wheel is rotating slowly.

[0083] If the steering wheel rotation rate (also referred to as the angular rate) is greater than or equal to the set second rate threshold (for example, the angular rate is greater than 10 degrees / second), it is considered that the current steering wheel swings too fast and friction torque self-learning is not performed.

[0084] S505 and S506 can be used to determine whether the friction torque can be self-learned in the straight-ahead state.

[0085] In one example, when the current driving state of the vehicle is a straight-ahead state, calculating and storing the friction torque may include: when the vehicle's rotation rate is greater than a set first rate threshold (YR>0.2 degrees / second) and the steering wheel's rotation rate is less than a set second rate threshold (angle rate<10 degrees / second), calculating the friction torque based on the steering operation torque.

[0086] The running state of the vehicle satisfies the vehicle's rotation rate YR>0.2 degrees / second and the angular rate <10 degrees / second. It is judged that the current steering wheel is rotating slowly, the friction torque can be detected, and the friction torque self-learning can be performed.

[0087] S507: Friction torque of the current cycle=steering operation torque×2.

[0088] In one example, calculating the friction torque according to the steering operation torque may include:

[0089] The steering operation torque is multiplied by 2 to obtain the friction torque of the current cycle, and the friction torque of the current cycle is used as the friction torque for self-learning.

[0090] S508: Friction torque = (friction torque of the current cycle + friction torque of the previous cycle) / 2.

[0091] In order to prevent sudden changes, the friction torque of the current cycle obtained in S507 may be smoothed, and the smoothed friction torque is used as the friction torque for self-learning.

[0092] In one example, calculating the friction torque according to the steering operation torque may include:

[0093] The steering operation torque is multiplied by 2 to obtain the friction torque of the current cycle; the friction torque is determined according to the friction torque of the current cycle and the friction torque of the previous cycle, wherein the friction torque = (friction torque of the current cycle + friction torque of the previous cycle) / 2.

[0094] S508 is an optional step. When the friction torque determined in step S507 is used as the friction torque for self-learning, S508 may not be executed.

[0095] S509: Set the straight-ahead status bit to OFF.

[0096] The friction torque can be self-learned while the vehicle is moving straight ahead, preventing the friction characteristics from being affected by the temperature, vehicle weight or tire characteristics.

[0097] Figure 6 Flow chart of the friction torque learning method under the angle reversal state provided by the embodiment of the present disclosure, such as Figure 6 As shown, the friction torque learning method under the angle reversal state may include:

[0098] S601: Determine whether the rotation rate YR of the vehicle is less than 3 degrees / second. If so, execute S602; otherwise, execute S612.

[0099] The vehicle's rotation rate is 0.15 degrees / second < YR < 3 degrees / second, indicating that the vehicle has a significant deflection.

[0100] S602: Determine whether 1NM<steering operation torque<3NM. If so, execute S603; otherwise, execute S612. The steering operation torque is the operation torque input by the driver, and Newton meter (NM) is the torque unit.

[0101] The vehicle's 1NM<steering operating torque<3NM, indicating that there is an operating torque input by the driver.

[0102] S603: Determine whether the friction measurement status bit is ON. If so, execute S608; otherwise, execute S604.

[0103] The friction measurement status bit is an expression of the signal level. When the friction measurement status bit is ON, it indicates that the self-learning of the friction torque can be performed in the state of the angle reversal. When the friction measurement status bit is OFF, it indicates that the self-learning of the friction torque is not performed in the state of the angle reversal.

[0104] In one example, the friction measurement status bit can be set to binary "1" (or "0") to indicate that the friction measurement status bit is ON, and the friction measurement status bit can be set to binary "0" (or "1") to indicate that the friction measurement status bit is OFF.

[0105] S604: memorize the steering operation torque.

[0106] S605: memorize the vehicle's rotation rate YR.

[0107] S606: memorize the turning direction.

[0108] S607: Set the friction measurement status bit to ON.

[0109] If the vehicle's rotation rate YR < 3 degrees / second, 1NM < steering torque < 3NM, and the current friction measurement status bit is not ON, the steering torque, current YR and steering angle direction input by the driver are memorized, and the friction measurement status bit is set to ON. The steering angle direction can be represented by the steering signal, which is positive when the steering wheel angle is to the left and negative when the steering wheel angle is to the right.

[0110] Among them, S604, S605, S606 and S607 have no order of precedence.

[0111] S608: Determine whether the steering wheel angle is reversed. If so, execute S609; otherwise, execute S612.

[0112] If the vehicle's rotation rate YR < 3 degrees / second, 1NM < steering operation torque < 3NM, and the current friction measurement status bit is ON, self-learning of the friction torque is performed.

[0113] S609: Determine whether the difference between the current YR and the memory YR is greater than 0.2 degrees / second. If so, execute S610; otherwise, execute S612.

[0114] In one example, when the current driving state of the vehicle is a corner reversal state, calculating and storing the friction torque may include:

[0115] When the difference between the current vehicle's rotation rate (YR) and the memory vehicle's rotation rate is greater than a set difference threshold, the friction torque is calculated based on the current steering torque and the memory value of the steering torque, wherein the set threshold may be 0.2±0.05 degrees / second.

[0116] When the vehicle's current driving state is a corner reversal state, and the difference between the current YR and the memory YR is greater than 0.2 degrees / second, it means that the vehicle has a slight change in body posture, proving that the driver is operating the steering wheel. At this time, friction torque self-learning can be performed.

[0117] S610: Friction torque of current cycle = current steering operation torque - steering operation torque memory value.

[0118] In one example, calculating the friction torque according to the current steering operation torque and the steering operation torque memory value may include:

[0119] The friction torque of the current cycle is obtained by subtracting the steering operation torque memory value from the current steering operation torque, and the friction torque of the current cycle is used as the friction torque for self-learning.

[0120] S611: Friction torque = (friction torque of the current cycle + friction torque of the previous cycle) / 2.

[0121] In order to prevent sudden changes, the friction torque of the current cycle obtained in S610 may be smoothed, and the smoothed friction torque is used as the friction torque for self-learning.

[0122] In one example, calculating the friction torque according to the current steering operation torque and the steering operation torque memory value may include:

[0123] The friction torque of the current cycle is obtained by subtracting the steering operation torque memory value from the current steering operation torque; the friction torque is determined according to the friction torque of the current cycle and the friction torque of the previous cycle, wherein the friction torque = (friction torque of the current cycle + friction torque of the previous cycle) / 2.

[0124] S611 is an optional step. When the friction torque determined in step S610 is used as the friction torque for self-learning, S611 may not be executed.

[0125] S612: Set the friction measurement status bit to OFF.

[0126] The friction torque can be self-learned when the vehicle is in a corner reversal state, preventing the friction characteristics from being affected by the temperature, vehicle weight or tire characteristics.

[0127] Figure 7 A structural block diagram of a driving assistance system provided by an embodiment of the present disclosure, such as Figure 7As shown, the input signal of the driving assistance may include at least one of the following sensor signals: a turn signal switch 101 that can detect the driver's turn signal operation, an accelerator pedal sensor 102 that detects the driver's throttle operation, a brake pedal sensor 103 that detects the driver's brake operation, a steering angle sensor 104 that detects the driver's steering operation, a torque sensor 105 that detects the driver's steering operation force, a vehicle speed sensor 106 that detects the vehicle speed, a radar sensor 107 that detects the surrounding environment of the vehicle, a camera sensor 108, a yaw rate sensor 109 that detects the vehicle's motion state, a longitudinal acceleration sensor 110, a lateral acceleration sensor 111, a wheel speed sensor FR112 that detects the speeds of four wheels, a wheel speed sensor FL113, a wheel speed sensor RR114, and a wheel speed sensor RL115. Among them, the wheel speed sensor FR, the wheel speed sensor FL, the wheel speed sensor RR, and the wheel speed sensor RL are respectively arranged on the left front wheel, the right front wheel, the left rear wheel, and the right rear wheel of the vehicle.

[0128] The driving assistance ECU 200 may include a steering assist function 201 .

[0129] The output signal of the driving assistance may include at least one of the following sensor signals: the engine ECU301 that controls acceleration and the engine that performs acceleration control, the brake ECU302 that controls deceleration and the brake system that performs deceleration control, the steering ECU303 that controls lateral movement and the lateral movement system that performs lateral control, and the display ECU304 and its display device that provide the driver with vehicle status and function control status light information.

[0130] In an exemplary embodiment of the present disclosure, a driving environment of a vehicle may be identified by a driving environment perception sensor. Figure 8 A structural block diagram of a driving environment perception sensor provided in an embodiment of the present disclosure, such as Figure 8 As shown, the driving environment around the vehicle can be detected by a driving environment perception sensor composed of a radar sensor 107 and a camera sensor 108.

[0131] The driving environment perception sensor may include at least one of the following: a front driving environment perception radar sensor RFC501, a front right driving environment perception radar sensor RFR503, a front left driving environment perception radar sensor RFL502, a front driving environment perception camera sensor CFC510, a camera sensor SVL512 for detecting the driving environment on the left side of the vehicle, a camera sensor SVR511 for detecting the driving environment on the right side of the vehicle, a radar sensor RRC506 for detecting the driving environment directly behind, a radar sensor RRR505 for detecting the right rear driving environment, and a radar sensor RRL504 for detecting the left rear driving environment.

[0132] As long as the driving environment can be detected, there is no specific requirement for the type of sensor (radar, lidar, ultrasonic, camera, etc.). The sensor that detects the driving environment can detect and identify the speed, relative speed, position, angle, size, etc. of the three-dimensional objects around the vehicle. Figure 8 There are nine sensors in total. If the sensor configuration can ensure 360-degree detection around the vehicle, there is no specific requirement for the number of sensors.

[0133] Fig. 9 A structural block diagram of a driving assistance device provided in an embodiment of the present disclosure, such as Fig. 9 As shown, the driving assistance device may include: a calculation module 91 , a judgment module 92 , a conversion module 93 and an output control module 94 .

[0134] The calculation module is configured to calculate the target trajectory of the vehicle according to the identified vehicle driving environment and then obtain the target turning angle. The calculation module can be provided with a steering assist function, which calculates the target trajectory of the vehicle based on the result identified by the camera sensor, and then calculates the target turning angle based on the target trajectory.

[0135] The judging module is configured to judge whether the steering is in a transition state according to the vehicle driving information and the target turning angle, and obtain the friction torque when the steering is judged to be in a transition state. The judging module can judge whether the steering is in a transition state according to the vehicle driving information (such as vehicle speed and / or steering wheel angle) and the target turning angle.

[0136] The conversion module is configured to calculate the torque required to achieve the target rotation angle, adjust the torque according to the friction torque, and obtain the adjusted torque. The conversion module converts the calculated target rotation angle into a torque, and can adjust the converted torque by the friction torque.

[0137] The output control module is configured to control the electric power steering to steer according to the adjusted torque. The output control module can send the torque adjusted by the friction torque to the EPS to achieve a steering assist function.

[0138] The driving assistance device provided in the embodiment of the present disclosure is used to perform Figure 2 The technical solution of the method embodiment shown has similar implementation principles and effects, which will not be repeated here.

[0139] In an exemplary embodiment of the present disclosure, Fig. 9 As shown, the driving assistance device may further include: a feedforward control module 95 and a feedback control module 96 .

[0140] The feedforward control module is configured to perform feedback control on the target turning angle; the feedforward control module can adjust the feedforward gain according to the determination result of the determination module.

[0141] The feedback control module is configured to perform feedforward control on the target turning angle when the steering is in a transition state; the feedback control module can adjust the feedback control gain according to the difference between the target turning angle and the current turning angle.

[0142] The conversion module calculates the torque required to achieve the target angle in the following way: The torque required to achieve the target angle is calculated based on the angle sum after feedback control and feedforward control. When the steering is in a transitional state, the conversion module converts the angle calculated based on feedforward control and feedback control into torque, adds it to the friction torque, and obtains the final requested torque, which is sent to the EPS ECU through the output control module.

[0143] In an exemplary embodiment of the present disclosure, the judging module judges whether the steering is in a transition state according to the vehicle driving information and the target turning angle, which may include:

[0144] comparing an actual steering wheel angle of the vehicle to a target angle;

[0145] When the target angle is inconsistent with the actual steering wheel angle and the change of the target angle meets the set angle change condition, it is determined that the steering is in a transition state;

[0146] The set angle change condition includes at least one of the following: the target angle remains unchanged for a certain period of time, the target angle changes from increasing to decreasing, and the target angle changes from decreasing to increasing.

[0147] In an exemplary embodiment of the present disclosure, the determination module is further configured to:

[0148] When the target angle is consistent with the actual steering wheel angle, or the target angle changes in the opposite direction of the actual steering wheel angle, it is determined that the steering is in a non-transition state.

[0149] In an exemplary embodiment of the present disclosure, the conversion module adjusts the torque according to the friction torque to obtain the adjusted torque, which may include:

[0150] Add the friction torque and the torque to get the adjusted torque.

[0151] In an exemplary embodiment of the present disclosure, the determination module acquires the friction torque, which may include:

[0152] Get the set friction torque;

[0153] or,

[0154] Obtain the friction torque obtained by self-learning the friction characteristics during driving.

[0155] In an exemplary embodiment of the present disclosure, the determination module is further configured to:

[0156] The friction torque is obtained by self-learning the friction characteristics during driving: the current driving state of the vehicle is obtained during driving, and when the current driving state of the vehicle meets the set conditions, the friction torque is calculated and stored.

[0157] In an exemplary embodiment of the present disclosure, the current driving state of the vehicle satisfies a set condition, which may include: the current driving state of the vehicle is a straight driving state, or the current driving state of the vehicle is a corner reversal state.

[0158] In an exemplary embodiment of the present disclosure, when the current driving state of the vehicle is a straight driving state, the judgment module calculating and storing the friction torque may include:

[0159] When the vehicle's rotation rate is greater than a set first rate threshold (YR>0.2 degrees / second) and the steering wheel's rotation rate is less than a set second rate threshold (angle rate<10 degrees / second), the friction torque is calculated based on the steering operation torque.

[0160] In an exemplary embodiment of the present disclosure, the determination module calculates the friction torque according to the steering operation torque, which may include:

[0161] Multiply the steering operation torque by 2 to obtain the friction torque of the current cycle;

[0162] The friction torque is determined according to the friction torque of the current cycle and the friction torque of the previous cycle, wherein the friction torque=(friction torque of the current cycle+friction torque of the previous cycle) / 2.

[0163] In an exemplary embodiment of the present disclosure, when the current driving state of the vehicle is a corner reversal state, the judgment module calculates and stores the friction torque, which may include:

[0164] When the difference between the rotation rate of the current vehicle and the rotation rate of the memorized vehicle is greater than a set difference threshold, the friction torque is calculated according to the current steering operation torque and the steering operation torque memory value.

[0165] In an exemplary embodiment of the present disclosure, the determination module calculates the friction torque according to the current steering operation torque and the steering operation torque memory value, which may include:

[0166] Subtract the steering operation torque memory value from the current steering operation torque to obtain the friction torque of the current cycle;

[0167] The friction torque is determined according to the friction torque of the current cycle and the friction torque of the previous cycle, wherein the friction torque=(friction torque of the current cycle+friction torque of the previous cycle) / 2.

[0168] In an exemplary embodiment of the present disclosure, the calculation module calculates the torque required to achieve the target rotation angle, which may include:

[0169] Feedback control of the target turning angle and feedforward control of the target turning angle when the steering is in a transition state;

[0170] The torque required to achieve the target angle is calculated based on the angle after feedback control and feedforward control.

[0171] It will be appreciated by those skilled in the art that all or some of the steps, systems, and functional modules / units in the methods disclosed above may be implemented as software, firmware, hardware, and appropriate combinations thereof. In hardware implementations, the division between the functional modules / units mentioned in the above description does not necessarily correspond to the division of physical components; for example, a physical component may have multiple functions, or a function or step may be performed by several physical components in cooperation. Some or all components may be implemented as software executed by a processor, such as a digital signal processor or a microprocessor, or implemented as hardware, or implemented as an integrated circuit, such as an application-specific integrated circuit. Such software may be distributed on a computer-readable medium, which may include a computer storage medium (or non-transitory medium) and a communication medium (or temporary medium). As known to those skilled in the art, the term computer storage medium includes volatile and non-volatile, removable and non-removable media implemented in any method or technology for storing information (such as computer-readable instructions, data structures, program modules, or other data). Computer storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical disk storage, magnetic cassettes, magnetic tapes, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to store the desired information and can be accessed by a computer. In addition, it is well known to those of ordinary skill in the art that communication media typically contain computer-readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave or other transport mechanism, and may include any information delivery media.

Claims

1. A method for processing friction characteristics of a steering system, It is characterized in that include: The target turning angle is obtained by calculating the target trajectory of the vehicle according to the identified vehicle driving environment; Determining whether the steering is in a transition state according to the vehicle driving information and the target turning angle, and obtaining the friction torque when it is determined that the steering is in a transition state; Calculating the torque required to achieve the target rotation angle, adjusting the torque according to the friction torque, and obtaining an adjusted torque; Controlling the electric power steering (EPS) to steer according to the adjusted torque; Wherein, judging whether the steering is in a transition state according to the vehicle driving information and the target turning angle includes: comparing an actual steering wheel angle of the vehicle with the target angle; When the target angle is inconsistent with the actual steering wheel angle and the change of the target angle meets the set angle change condition, it is determined that the steering is in a transition state; The set angle change condition includes at least one of the following: the target angle remains unchanged for a certain period of time, the target angle changes from increasing to decreasing, and the target angle changes from decreasing to increasing; The calculation of the torque required to achieve the target rotation angle includes: performing feedback control on the target turning angle, and performing feedforward control on the target turning angle when the steering is in a transition state; The torque required to achieve the target rotation angle is calculated based on the angle after feedback control and the feedforward control.

2. The method according to claim 1, It is characterized in that The method further comprises: When the target angle is consistent with the actual steering wheel angle, or the target angle changes in a direction opposite to the actual steering wheel angle, it is determined that the steering is in a non-transition state.

3. The method according to claim 1, It is characterized in that The step of adjusting the torque according to the friction torque to obtain the adjusted torque includes: The friction torque and the torque are added to obtain the adjusted torque.

4. The method according to claim 1, It is characterized in that The obtaining of the friction torque comprises: Get the set friction torque; or, Obtain the friction torque obtained by self-learning the friction characteristics during driving.

5. The method according to claim 4, It is characterized in that The method further comprises: The friction torque is obtained by self-learning the friction characteristics during driving: the current driving state of the vehicle is obtained during driving, and when the current driving state of the vehicle meets the set conditions, the friction torque is calculated and stored.

6. The method according to claim 5, It is characterized in that The current driving state of the vehicle satisfies the set conditions, including: the current driving state of the vehicle is a straight driving state, or the current driving state of the vehicle is a corner reversal state.

7. The method according to claim 6, It is characterized in that When the current driving state of the vehicle is a straight driving state, the calculating and storing the friction torque includes: When the rotation rate of the vehicle is greater than a set first rate threshold and the rotation rate of the steering wheel is less than a set second rate threshold, the friction torque is calculated according to the steering operation torque.

8. The method according to claim 7, It is characterized in that The calculating the friction torque according to the steering operation torque comprises: Multiplying the steering operation torque by 2 to obtain the friction torque of the current cycle; The friction torque is determined according to the friction torque of the current cycle and the friction torque of the previous cycle, wherein the friction torque=(friction torque of the current cycle+friction torque of the previous cycle) / 2.

9. The method according to claim 6, It is characterized in that When the current driving state of the vehicle is a turning angle reversal state, the calculating and storing the friction torque includes: When the difference between the rotation rate of the current vehicle and the rotation rate of the memorized vehicle is greater than a set difference threshold, the friction torque is calculated according to the current steering operation torque and the steering operation torque memory value.

10. The method according to claim 9, It is characterized in that The calculating the friction torque according to the current steering operation torque and the steering operation torque memory value includes: Subtracting the steering operation torque memory value from the current steering operation torque to obtain the friction torque of the current cycle; The friction torque is determined according to the friction torque of the current cycle and the friction torque of the previous cycle, wherein the friction torque=(friction torque of the current cycle+friction torque of the previous cycle) / 2.

11. A driving assistance device, used to execute the method for processing friction characteristics of a steering system according to any one of claims 1 to 10, It is characterized in that include: Calculation module, judgment module, conversion module and output control module; The calculation module is configured to calculate the target trajectory of the vehicle according to the identified vehicle driving environment and then obtain the target turning angle; The judgment module is configured to judge whether the steering is in a transition state according to the vehicle driving information and the target turning angle, and obtain the friction torque when it is judged that the steering is in a transition state; The conversion module is configured to calculate the torque required to achieve the target rotation angle, adjust the torque according to the friction torque, and obtain the adjusted torque; The output control module is configured to control the electric power steering (EPS) to steer according to the adjusted torque.

12. The device according to claim 11, It is characterized in that The device further comprises: a feedforward control module and a feedback control module, The feedforward control module is configured to perform feedback control on the target turning angle; The feedback control module is configured to perform feedforward control on the target turning angle when the steering is in a transition state; The conversion module calculates the torque required to achieve the target rotation angle in the following manner: the torque required to achieve the target rotation angle is calculated based on the angle after feedback control and the feedforward control.

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