Control method and control system for driving system of mobile vehicle

Abstract

The invention discloses a control method and a control system of a driving system of a mobile vehicle. The control method of the driving system is applied to the mobile vehicle and comprises the following steps: (A) calculating a target yaw rate of the mobile vehicle; (B) calculating the difference between the actual yaw rate and the target yaw rate of the mobile carrier to obtain a yaw error value; and (C) when the yaw error value is greater than a third reference value, controlling the torque output by the first driving element and / or the second driving element so as to reduce or eliminate the yaw error value. Therefore, the control method and the control system of the driving system of the mobile vehicle can eliminate the turning inner wheel difference of the mobile vehicle.

Description

Technical Field

[0001] The present invention relates to a control method and a control system, and in particular to a control method and a control system for a mobile vehicle having a driving system capable of suppressing inner wheel difference when the mobile vehicle turns. Background Art

[0002] When the vehicle is driving, four-wheel steering models equipped with steering systems at both the front and rear can effectively improve the vehicle's flexibility and dynamics, such as reducing the turning radius, improving steering flexibility and stability, and eliminating the inner wheel difference in turns. However, because the rear axle needs to be equipped with a steering system, it will occupy a larger rear wheel room space, resulting in a pain point of reduced rear seat comfort and luggage compartment usable space. Therefore, the rear axle steering system currently on the market mainly uses a small-angle steering system to reduce the problem of occupying rear seat and luggage compartment space, but it still cannot completely solve the problem.

[0003] Therefore, how to overcome the above-mentioned defects by improving the system architecture has become one of the important issues that the technical field wants to solve. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a control method and a control system for a driving system of a mobile vehicle in view of the deficiencies in the prior art.

[0005] In order to solve the above technical problems, one of the technical solutions adopted by the present invention is to provide a control method of a drive system, which is applied to a mobile vehicle, including: (A) calculating a target yaw rate of the mobile vehicle; (B) calculating the difference between the actual yaw rate of the mobile vehicle and the target yaw rate to obtain a yaw error value; and (C) when the yaw error value is greater than a third reference value, controlling the torque output by the first drive element and / or the second drive element to reduce or eliminate the yaw error value.

[0006] In one feasible or preferred embodiment, the control method further includes: obtaining a steering angle value of the mobile vehicle, and when the steering angle value is greater than a first reference value, executing steps (A), (B), and (C).

[0007] In one feasible or preferred embodiment, step (C) includes: calculating a first corrected torque value based on the yaw error value; calculating a second corrected torque value based on the steering angle value and the speed of the mobile vehicle; adjusting the torque output by the first drive element based on the sum of the first corrected torque value and the second corrected torque value weighted by weighting coefficients corresponding to the first drive element, and / or adjusting the torque output by the second drive element based on the sum of the first corrected torque value and the second corrected torque value weighted by weighting coefficients corresponding to the second drive element.

[0008] In one feasible or preferred embodiment, step (C) further includes: obtaining a first wheel slip difference and a second wheel slip difference of the mobile vehicle; when the first wheel slip difference is greater than a fourth reference value, calculating a third corrected torque value based on the first wheel slip difference, and further incorporating the third corrected torque value into a basis for adjusting the torque output by the first drive element, and / or when the second wheel slip difference is greater than a fourth reference value, calculating a fourth corrected torque value based on the second wheel slip difference, and further incorporating the fourth corrected torque value into a basis for adjusting the torque output by the second drive element.

[0009] In one feasible or preferred embodiment, the target yaw rate is a function of the steering angle value, the speed of the mobile vehicle, and at least one parameter specific to the mobile vehicle.

[0010] In one feasible or preferred embodiment, when the yaw error value is less than a third reference value, the method further includes: obtaining a first wheel slip difference and a second wheel slip difference of the mobile vehicle; when the first wheel slip difference is greater than a fourth reference value, calculating a third correction torque value based on the first wheel slip difference, and adjusting the torque output by the first drive element based on the third correction torque value to reduce or eliminate the first wheel slip difference, and / or when the second wheel slip difference is greater than a fourth reference value, calculating a fourth correction torque value based on the second wheel slip difference, and adjusting the torque output by the second drive element based on the fourth correction torque value to reduce or eliminate the second wheel slip difference.

[0011] In one feasible or preferred embodiment, the first driving element and the second driving element drive the left rear wheel and the right rear wheel of the mobile vehicle respectively, and the target yaw rate is based on reducing or eliminating the inner wheel difference of the mobile vehicle when turning so as to maximize the overlap between the trajectories of the left rear wheel and the right rear wheel and the trajectories of the left front wheel and the right front wheel of the mobile vehicle.

[0012] In one feasible or preferred embodiment, the steering angle value is obtained from the steering angle of the wheel end of the mobile vehicle, the overall steering angle of the mobile vehicle, the steering angle of the steering wheel or steering controller, the steering angle of the steering motor, or the stroke of the steering gear tie rod.

[0013] In order to solve the above-mentioned technical problems, another technical solution adopted by the present invention is to provide a control system of a mobile vehicle, which has at least one control unit, and the control system executes any one of the above-mentioned control methods through the at least one control unit.

[0014] One of the beneficial effects of the present invention is that the control method of the drive system provided by the present invention can eliminate the occurrence of inner wheel difference in turning of the mobile vehicle through the technical solution of "(A) calculating the target yaw rate of the mobile vehicle; (B) calculating the difference between an actual yaw rate of the mobile vehicle and the target yaw rate to obtain a yaw error value; and (C) when the yaw error value is greater than a third reference value, controlling the torque output by the first drive element and / or a second drive element to reduce or eliminate the yaw error value".

[0015] Another beneficial effect of the present invention is that the control system of the mobile vehicle provided by the present invention can eliminate the occurrence of inner wheel difference in turning of the mobile vehicle through the technical solution of "having at least one control unit, and the control system executes any one of the above-mentioned control methods through the at least one control unit".

[0016] To further understand the features and technical contents of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are only for reference and description and are not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a first flow chart of a control method for a driving system according to an embodiment of the present invention.

[0018] Figure 2 It is a curve diagram of the actual vehicle calibration table 1 according to an embodiment of the present invention.

[0019] Figure 3 Schematic diagram of the actual vehicle calibration table 2 according to an embodiment of the present invention.

[0020] Figure 4 It is a first functional block diagram of a control system of a mobile vehicle according to an embodiment of the present invention.

[0021] Figure 5 This is a second flow chart of the control method of the driving system according to an embodiment of the present invention.

[0022] Figure 6 It is a second functional block diagram of the control system of the mobile vehicle according to an embodiment of the present invention.

[0023] Figure 7 It is a third functional block diagram of the control system of the mobile vehicle according to an embodiment of the present invention.

[0024] Figure 8 It is a fourth functional block diagram of the control system of the mobile vehicle according to an embodiment of the present invention.

[0025] Reference numerals:

[0026] Z: control system; Z1: control unit; Z2: operation control unit; Z3: motor control unit; Z4: electronic body stability control unit; Z5: chassis domain control unit; M: mobile vehicle; M1: steering angle sensor; M2: real vehicle sensor; 3: first drive element; M4: second drive element; M5: vehicle speed sensor. DETAILED DESCRIPTION

[0027] The following is an explanation of the implementation methods of the "control method and control system for the drive system of a mobile vehicle" disclosed in the present invention through specific embodiments. Those skilled in the art can understand the advantages and effects of the present invention from the contents disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and the details in this specification can also be modified and changed in various ways based on different viewpoints and applications without departing from the concept of the present invention. The following implementation methods will further explain the relevant technical contents of the present invention in detail, but the disclosed contents are not intended to limit the scope of protection of the present invention.

[0028] It should be understood that, although the terms "first", "second", "third", etc. may be used herein to describe various components or signals, these components or signals should not be limited by these terms. These terms are mainly used to distinguish one component from another component, or one signal from another signal. In addition, the term "or" used herein may include any one or more combinations of the associated listed items depending on the actual situation.

[0029] Example

[0030] See also Figures 1 to 8 , respectively, are a first flow chart of the control method of the drive system of an embodiment of the present invention, a curve chart of the actual vehicle calibration table 1, a schematic diagram of the actual vehicle calibration table 2, a first functional block diagram of the control system of the mobile vehicle, a second flow chart of the control method of the drive system, a second functional block diagram of the control system of the mobile vehicle, a third functional block diagram of the control system of the mobile vehicle, and a fourth functional block diagram of the control system of the mobile vehicle. As shown in the above figures, the first embodiment of the present invention provides a control method of a drive system, which is applied to a mobile vehicle M, that is, the control method of the present invention can be applied to the drive system of the mobile vehicle M; wherein the mobile vehicle M can be a vehicle that uses electricity as a power source and has four or more wheels, that is, an electric vehicle, but is not limited thereto, and the mobile vehicle M can also be a hybrid electric vehicle or a fuel vehicle. The control method of the drive system of the present invention includes at least the following steps:

[0031] (A) Calculate the target yaw rate of the mobile vehicle M;

[0032] (B) calculating the difference between the actual yaw rate and the target yaw rate of the mobile vehicle M to obtain a yaw error value; and

[0033] (C) When the yaw error value is greater than a third reference value, controlling the torque output by the first driving element and / or the second driving element to reduce or eliminate the yaw error value.

[0034] The control method of the driving system of the present invention may further include: obtaining a steering angle value of the mobile vehicle M, and when the steering angle value is greater than a first reference value, executing steps (A), (B), and (C).

[0035] For example, with Figure 1 , Figure 2 and Figure 4 As shown, when the control method of the driving system of the present invention is applied to a mobile vehicle M, the steering angle value of the mobile vehicle M can be first obtained through the steering angle sensor M1 of the mobile vehicle M; wherein, the steering angle value is obtained through the steering angle sensor M1 to obtain the steering angle of the wheel end of the mobile vehicle M, the overall steering angle of the mobile vehicle M, the steering angle of the steering wheel or the direction controller, the steering angle of the steering motor, or the travel of the steering gear tie rod, but not limited to this. In addition, it is determined whether the steering angle value is greater than the first reference value (i.e., step S100); wherein, the technicians in the technical field to which the present invention belongs can set the first reference value based on common knowledge, actual operation needs, differences in hardware design, etc. considerations. When it is determined that the steering angle value is less than or equal to the first reference value, step S101 is entered to determine that the mobile vehicle M is currently in the straight driving mode; wherein, if it is in the straight driving mode, there is no need to set different driving torques for the left rear wheel and the right rear wheel, and the vehicle enters the longitudinal control mode.

[0036] When it is determined that the steering angle value is greater than the first reference value, it is determined that the mobile vehicle M is currently in the steering mode. At this time, the process proceeds to step S102 to calculate the target yaw rate of the mobile vehicle M, that is, to calculate the theoretical yaw rate ω of the vehicle through a vehicle model (a common vehicle motion model such as a bicycle model, but not limited to this) T , and set the second reference value according to the actual vehicle calibration result, and multiply the theoretical yaw rate by the second reference value as the target yaw rate; wherein the target yaw rate can be a function of the steering angle value, the vehicle speed of the mobile vehicle M hardware, and at least one parameter specific to the mobile vehicle M.

[0037] Next, the process proceeds to step S104, where the current vehicle yaw rate (ie, actual yaw rate ω) of the mobile vehicle M is obtained by a sensor of the mobile vehicle M (eg, the actual vehicle sensor M2). S ), and subtract the actual yaw rate ω from the target yaw rate S Then, we can get the yaw error value ω e (i.e. yaw rate error).

[0038] Among them, the theoretical yaw rate ω in the above T It can be calculated according to the following formula 1:

[0039]

[0040] In the above formula 1, δ is the steering angle, Vx is the vehicle speed, L is the wheelbase, and K is the understeer gradient. K can be determined by a formula that considers the steering characteristics of the front and rear tires and the wheelbase or a real vehicle calibration value.

[0041] The second reference value (N) mentioned above can be obtained according to the following formula 2 and the actual vehicle calibration table, for example: Figure 2 The actual vehicle calibration table 1 (Adjustment_Table1) shown:

[0042] N=Adjustment_Table1(δ,L f , L r , Vx, C f , C r ) (Formula 2)

[0043] In the above formula 2, δ is the steering angle, Lf is the distance from the center of gravity to the front wheelbase, and L r is the distance from the center of gravity to the rear wheelbase, Vx is the vehicle speed, C f is the front wheel steering stiffness, C r is the rear wheel steering stiffness.

[0044] Among them, the yaw error value ω in the above e It can be calculated using the following formula 3:

[0045] ω e =ω T ×N-ω S (Formula 3)

[0046] In the above formula 3, N is the second reference value, ω S It is the current vehicle yaw rate measured by the real vehicle sensor M2.

[0047] Next, after the yaw error value is obtained, step S106 is entered to determine whether the absolute value of the yaw error value is greater than a third reference value; wherein the third reference value may be set by a person skilled in the art in the technical field to which the present invention belongs based on factors such as actual needs, differences in hardware design, etc. When it is determined that the yaw error value is greater than the third reference value, the torque output by the first drive element M3 and / or the second drive element M4 is controlled to reduce or eliminate the yaw error value.

[0048] It is worth noting that the first driving element M3 and the second driving element M4 may be the driving system of the mobile vehicle M, and may respectively drive, for example, the left rear wheel and the right rear wheel of the mobile vehicle M. The target yaw rate may be based on reducing or eliminating the inner wheel difference of the mobile vehicle M when turning so as to maximize the overlap between the trajectories of the left rear wheel and the right rear wheel and the trajectories of the left front wheel and the right front wheel of the mobile vehicle M. In other words, the inner wheel difference is mainly caused by the different trajectories of the rear axle wheels and the front axle wheels. If the trajectory of the rear axle wheels can be controlled to be consistent with that of the front axle wheels or as consistent as possible, the inner wheel difference can be eliminated or minimized.

[0049] Furthermore, the control method of the driving system of the present invention may further include the following steps in step (C):

[0050] Calculate the first correction torque value M based on the yaw error value Z_FB ;

[0051] The second correction torque value T is calculated based on the steering angle value and the vehicle speed of the mobile vehicle M. FF ;

[0052] The torque output by the first drive element M3 is adjusted based on the sum of the first corrected torque value and the second corrected torque value weighted by the weighting coefficients corresponding to the first drive element M3, and / or the torque output by the second drive element M4 is adjusted based on the sum of the first corrected torque value and the second corrected torque value weighted by the weighting coefficients corresponding to the second drive element M4.

[0053] For example, with Figure 1 , Figure 3 and Figure 4 As shown, when it is determined that the yaw error value is greater than the third reference value, step S108 is entered, and a feedback control action can be performed according to the yaw error value, that is, the first correction torque value MZ_FB required to eliminate the yaw error value is calculated and converted into a yaw correction driving torque. Z_FB It can be calculated using the following formula 4:

[0054]

[0055] In the above formula 4, K P is the proportional gain coefficient, K I is the integral gain coefficient, K D is the differential gain coefficient.

[0056] Next, the process proceeds to step S110, where a second modified torque value T is obtained according to the steering angle value obtained by the steering angle sensor M1 of the mobile vehicle M and the vehicle speed obtained by the vehicle speed sensor M5 of the mobile vehicle M. FF Among them, according to the following formula 5 and the actual vehicle calibration table, for example Figure 5The feedforward torque (which is a function of vehicle speed and steering angle) shown in the actual vehicle calibration table 2 (Adjustment_Table2) is used to obtain the second correction torque value T FF (Can be used to pre-apply yaw correction drive torque):

[0057] T FF =Adjustment_Table2(δ,Vx) (Formula 5)

[0058] In the above formula 5, δ is the steering angle, and Vx is the vehicle speed.

[0059] Next, based on the first correction torque value M Z_FB and the second corrected torque value T FF The torque output by the first drive element M3 (ie, the modified drive torque T of the first drive element M3) is adjusted by the weighted sum of the weighted coefficients corresponding to the first drive element M3. RL ); wherein the first driving element M3 may be a driving motor of the left rear wheel, but is not limited thereto. In practical applications, the first driving element M3 may also be a driving motor of the front wheel or the right wheel. wherein the modified driving torque T of the first driving element M3 is calculated according to the following formula 6: RL :

[0060] T RL =T1+M Z_FB ×K q_RL +T FF ×K FF_RL (Formula 6)

[0061] Among them, T1 is the corrected front left rear wheel drive torque, K q_RL is the left rear wheel drive torque conversion factor, K FF_RL is the left rear wheel yaw correction drive torque correction coefficient.

[0062] Furthermore, the torque output by the second drive element M4 (i.e., the modified drive torque T of the second drive element M4) can be adjusted based on the sum of the first modified torque value and the second modified torque value weighted by the weighting coefficient corresponding to the second drive element M4. RR ); wherein the second driving element M4 may be a driving motor of the right rear wheel, but is not limited thereto. In practical applications, the first driving element M3 may also be a driving motor of the front wheel or the left wheel. wherein the modified driving torque T of the second driving element M4 is calculated according to the following formula 7: RR :

[0063] T RR =T2+M Z_FB ×K q_RR +T FF ×K FF_RR (Formula 7)

[0064] Among them, T2 is the corrected front right rear wheel drive torque, K q_RR is the right rear wheel drive torque conversion coefficient, K FF_RR is the right rear wheel yaw correction drive torque correction coefficient.

[0065] Next, according to the corrected driving torque T of the first driving element M3 RL Adjust the torque output by the first drive element M3, and / or adjust the drive torque T of the second drive element M4 according to the modified RR Adjust the torque output by the second driving element M4.

[0066] Furthermore, the control method of the driving system of the present invention may further include the following steps in step (C):

[0067] Get the first wheel slip difference κ of the moving vehicle M RL The difference between the second wheel slip and RR ;

[0068] When the first wheel slip value κ RL When the third correction torque value T is greater than the fourth reference value, the third correction torque value T is calculated based on the first wheel slip value. κ_Modify (κ RL ), further incorporating the third modified torque value into the basis for adjusting the torque output by the first drive element M3, and / or when the second wheel slip difference κ RR When it is greater than the fourth reference value, a fourth correction torque value T is calculated based on the second wheel slip value. κ_Modify (κ RR ), further incorporating the fourth modified torque value into the basis for adjusting the torque output by the second driving element M4;

[0069] When the first wheel slip value κ RL When the torque T of the first drive element M3 is less than or equal to the fourth reference value, the torque output by the first drive element M3 is adjusted based on the sum of the first correction torque value and the second correction torque value weighted by the weighting coefficient corresponding to the first drive element M3 (the corrected driving torque T of the first drive element M3). RL ), and / or when the second wheel slip difference κ RR When the torque T of the second drive element M4 is less than or equal to the fourth reference value, the torque output by the second drive element M4 (i.e., the corrected drive torque T of the second drive element M4) is adjusted based on the sum of the first corrected torque value and the second corrected torque value weighted by the weighting coefficient corresponding to the second drive element M4. RR ).

[0070] For example, with Figures 1 to 4As shown, before outputting the modified driving torque of the left and right wheels of the rear axle, the longitudinal force characteristics under the tire slip can also be considered; because when the slip is too large, the longitudinal force of the tire will decrease, a slip controller can be designed to limit the tire slip to ensure the stability of the vehicle performance. In the slip controller, the tire slip is calculated based on the wheel speed of the left and right wheels of the rear axle and the vehicle speed. Therefore, after step S110, the first wheel slip value κ of the mobile vehicle M can be further obtained RL The difference between the second wheel slip and RR , and determine the first wheel slip difference κ RL and / or the second wheel slip difference κ RR Is it greater than the fourth reference value (i.e., step S112). When the slip of the left and right wheels of the rear axle is greater than or equal to the fourth reference value, i.e., the first wheel slip value κ RL (such as corresponding to the left wheel of the rear axle) is greater than or equal to the fourth reference value and / or the second wheel slip value κ RR When the torque of the left and right wheels of the rear axle is greater than or equal to the fourth reference value (corresponding to the right wheel of the rear axle), the process proceeds to step S114, where it is determined that the slip is too large and the driving force of the left and right wheels of the rear axle needs to be adjusted to control the output torque of the left and right wheels of the rear axle under the premise of preventing the tires from losing grip. The fourth reference value can be set by a person skilled in the art based on common knowledge and taking into account factors such as actual needs.

[0071] In this case, the wheel speed sensor M6 of the mobile vehicle M can sense the wheel speed of each wheel, such as the wheel speed of the left rear wheel and the right rear wheel, and calculate the slip of the left rear wheel and the right rear wheel based on the sensed wheel speed. The left rear wheel slip (i.e., the first wheel slip value κ) can be calculated according to the following formulas 8 and 9: RL ) and the right rear wheel slip (i.e. the second wheel slip value κ RR ).

[0072]

[0073]

[0074] In the above formulas 8 and 9, V x_RL is the left rear wheel center speed, V x_RR is the right rear wheel center speed, and Vx is the vehicle speed.

[0075] That is to say, when the slip is too large, the loss of grip can be avoided by adjusting the distribution and size of the driving force of the left rear wheel and the right rear wheel to maintain the ability to achieve the target yaw rate. Therefore, the slip controller can calculate the corrected rear axle left wheel driving torque (i.e., the corrected driving torque T of the first driving element M3) respectively. RL ), the corrected rear axle right wheel driving torque (ie, the corrected driving torque T of the second driving element M4) RR)Required correction torque (T κ_Modify (κ RL ), T κ_Modify (κ RR )) and then add the corrected rear axle left wheel drive torque and the corrected rear axle right wheel drive torque to get the final output left rear wheel drive torque T RL_Final , right rear wheel drive torque T RR_Final The final output left rear wheel drive torque T can be calculated according to the following formulas 10 and 11: RL_Final , right rear wheel drive torque T RR_Final .

[0076] T RL_Final =T RL +T κ_Modify (κ RL ) (Formula 10)

[0077] T RR_Final =T RR +T κ_Modify (κ Rr ) (Formula 11)

[0078] On the contrary, when the first wheel slip value κ RL When the value is less than or equal to the fourth reference value, the process proceeds to step S116, and the weighted sum of the first modified torque value and the second modified torque value respectively with the weighted coefficient corresponding to the first driving element M3 (i.e., the modified driving torque T of the first driving element M3) is calculated. RL ), adjust the torque of the first drive element output M3; and when the second wheel slip difference κ RR When the first correction torque value and the second correction torque value are less than or equal to the fourth reference value, the process proceeds to step S116, and the correction torque T of the second driving element M4 is calculated based on the sum of the first correction torque value and the second correction torque value weighted by the weighting coefficient corresponding to the second driving element M4 (i.e., the correction torque T of the second driving element M4). RR ), adjust the torque output by the second driving element M4.

[0079] Therefore, the control method of the drive system of the present invention can be implemented through the above-mentioned technical scheme, through the control method of different output torques (i.e. vector torque) of the independent dual motors (i.e. the first drive element M3 and the second drive element M4) of the vehicle's rear axle, so that a vehicle equipped with only a front-wheel steering system can also have the special functions of a four-wheel steering vehicle, especially eliminating the inner wheel difference in turns, while avoiding the disadvantage of the rear-axle steering system occupying the rear wheel room space, so that the vehicle can still maintain the original rear seat and luggage compartment space.

[0080] Furthermore, through the control method of the drive system of the present invention, when the vehicle is turning, the required individual torque output of the two wheels of the rear axle is calculated based on the front wheel turning angle, so as to achieve the effect of eliminating the difference in trajectory between the rear wheels and the front wheels (that is, the trajectories of the front and rear inner wheels are consistent), thereby eliminating the inner wheel difference caused by steering geometry, so that the vehicle will not accidentally touch objects or pedestrians standing behind the vehicle when turning, thereby ensuring the safety of the vehicle itself and others.

[0081] In addition, when the yaw error value is less than the third reference value, the control method further comprises the following steps:

[0082] Get the first wheel slip difference κ of the moving vehicle M RL The difference between the second wheel slip and RR ;

[0083] When the first wheel slip value κ RL When the third correction torque value T is greater than the fourth reference value, the third correction torque value T is calculated based on the first wheel slip value. κ_Modify (κ RL ), based on the third modified torque value, adjusting the torque output by the first drive element M3 to reduce or eliminate the first wheel slip difference, and / or when the second wheel slip difference κ RR When it is greater than the fourth reference value, a fourth correction torque value T is calculated based on the second wheel slip value. κ_Modify (κ RR ), based on the fourth modified torque value, the torque output by the second driving element M4 is adjusted to reduce or eliminate the second wheel slip value.

[0084] When the first wheel slip value κ RL When the torque output by the first driving element M3 is not adjusted, and / or when the second wheel slip difference κ is less than or equal to the fourth reference value, the torque output by the first driving element M3 is not adjusted. RR When it is less than or equal to the fourth reference value, the torque output by the second driving element M4 is not adjusted.

[0085] For example, with Figures 2 to 5 As shown, when the absolute value of the yaw error value is less than or equal to the third reference value, it means that the yaw rate of the current vehicle is less than the yaw rate that can eliminate the inner wheel difference. The control system does not need to adjust the drive torque distribution of the left and right wheels of the rear axle, but only needs to check the wheel speed of the left and right wheels of the rear axle of the moving vehicle and the tire slip calculated by the vehicle speed of the moving vehicle. Therefore, when the absolute value of the yaw error value is less than or equal to the third reference value, step S118 is entered to obtain the first wheel slip value κ RL The difference between the second wheel slip K RR ; In this step, the first wheel slip difference κ is obtained RL The difference between the second wheel slip and RR The method is the same as the aforementioned step S112 and will not be specifically described here.

[0086] Next, enter step S120 to determine the first wheel slip difference κ RL The difference between the second wheel slip and RR Is it greater than the fourth reference value. When the slip is greater than or equal to the fourth reference value, the process proceeds to step S122, where it is determined that the slip is too large and a slip controller is required to adjust the driving force of the left and right wheels of the rear axle to prevent the tires from losing grip. Therefore, the wheel speed sensor M6 of the mobile vehicle M can sense the wheel speed of each wheel, such as the wheel speed of the left rear wheel and the right rear wheel, and the slip of the left rear wheel and the right rear wheel can be calculated based on the sensed wheel speed. The left rear wheel slip (i.e., the first wheel slip value κ) can be calculated based on the aforementioned formulas 8 and 9. RL ) and the right rear wheel slip (i.e. the second wheel slip value κ RR ).

[0087] Then, the slip controller can calculate the correction torque (i.e., the third correction torque value T κ_Modify (κ RL ), the fourth correction torque value T κ_Modify (κ RR ) can be obtained by the final output left rear wheel driving torque T RL_Final , right rear wheel drive torque T RR_Final Among them, the final output left rear wheel drive torque T RL_Fina1 , right rear wheel drive torque T RR_Final As shown in the following formulas 12 and 13.

[0088] T RL_Final =T1+T κ_Modify (κ RL ) (Formula 12)

[0089] T RR_Final =T2+T κ_Modify (κ RR ) (Formula 13)

[0090] When the slip is less than the fourth reference value, the process proceeds to step S124, and the torque output by the first driving element M3 and / or the second driving element M4 is not adjusted.

[0091] In addition, according to the above content, Figures 1 to 5 As shown, the present invention further provides a control system Z of a mobile vehicle M, which may have at least one control unit Z1, and the control system Z may execute the control method of the driving system through at least one control unit Z1. The control unit Z1 may be an electronic control device or a computing chip of the mobile vehicle, but is not limited thereto.

[0092] Furthermore, with Figure 6As shown, the control system Z of the present invention may also include an operation control unit Z2 and a motor control unit (MCU) Z3. The operation control unit Z2 and the motor control unit Z3 are connected via a controller area network (CAN) signal, and are used to obtain the steering angle value of the mobile vehicle M. In addition, the operation control unit Z2 is connected to the steering angle sensor M1, the actual vehicle sensor M2, and the vehicle speed sensor M5 via the controller area network signal. Therefore, the operation control unit Z2 can obtain the steering angle through the steering angle sensor M1. In addition, the operation control unit Z2 can be used to determine whether the steering angle value is greater than a first reference value, and is used to execute steps (A), (B), and (C), and then transmit the control signal of the controller area network to the motor control unit Z3. For another example, in conjunction with Figure 6 and Figure 7 It is known that Figure 7 The control system Z and Figure 6 Compared with the control system Z, it also includes an electronic body stability control unit Z4, and the computing control software is burned into the electronic body stability control unit Z4. The electronic body stability control unit Z4 includes the above-mentioned slip controller, and is connected to the steering angle sensor M1, the real vehicle sensor M2, the vehicle speed sensor M5, the wheel speed sensor M6 and the motor control unit Z3 through the controller area network signal. Since the electronic body stability control unit Z4 includes the slip controller and the signal is connected to the wheel speed sensor M6, Figure 7 The control system Z and Figure 6 Compared with the control system Z, it can use the electronic vehicle stability control unit Z4 to determine whether there is excessive slip at the wheel end and correct the torque accordingly. Figure 7 and Figure 8 It is known that Figure 8 The control system Z and Figure 7 The difference between the control system Z is that, Figure 8 The chassis domain control unit (DCU) Z5 replaces the Z control system Figure 7 The electronic body stability control unit Z4 and the motor control unit Z3 of the control system Z, and the calculation control software is burned into the chassis domain control unit Z5. The chassis domain control unit Z5 can obtain the steering angle value of the mobile vehicle M through the communication network, and can also be used to determine whether the steering angle value is greater than the first reference value, and is used to execute steps (A), (B), and (C).

[0093] However, the above example is only one feasible implementation example and is not intended to limit the present invention.

[0094] Advantageous Effects of Embodiments

[0095] One of the beneficial effects of the present invention is that the control method of the drive system provided by the present invention can eliminate the occurrence of the turning inner wheel difference of the mobile vehicle M by "(A) calculating the target yaw rate of the mobile vehicle M; (B) calculating the difference between the actual yaw rate of the mobile vehicle M and the target yaw rate to obtain a yaw error value; and (C) when the yaw error value is greater than a third reference value, controlling the torque output by the first drive element M3 and / or the second drive element M4 to reduce or eliminate the yaw error value a."

[0096] Another beneficial effect of the present invention is that the control system Z of the mobile vehicle M provided by the present invention can eliminate the occurrence of inner wheel difference in turning of the mobile vehicle M through the technical solution of "having at least one control unit Z1, and the control system Z executes the above-mentioned control method through at least one control unit Z1".

[0097] Furthermore, the rear-wheel drive system and control method of the present invention, through the above-mentioned technical scheme, starts from the perspective of vehicle integrated dynamic control, through the control method of different output torques of the independent dual motors of the rear axle (i.e., the first drive element M3 and the second drive element M4) (i.e., vector torque). When the vehicle is turning, the required individual torque outputs of the two wheels on the rear axle can be calculated according to the front wheel turning angle, thereby achieving the effect of eliminating the difference in trajectory between the rear wheels and the front wheels (i.e., the trajectories of the front and rear inner wheels are consistent), thereby eliminating the inner wheel difference caused by steering geometry.

[0098] The contents disclosed above are only preferred feasible embodiments of the present invention, and are not intended to limit the protection scope of the claims of the present invention. Therefore, all equivalent technical changes made using the contents of the present invention description and drawings are included in the protection scope of the claims of the present invention.

Claims

1. A control method for a drive system, characterized in that: Applied to a mobile vehicle, the control method includes: (A) calculating a target yaw rate of the mobile vehicle; (B) calculating the difference between the actual yaw rate of the mobile vehicle and the target yaw rate to obtain a yaw error value; and (C) When the yaw error value is greater than a third reference value, controlling the torque output by the first driving element and / or the second driving element to reduce or eliminate the yaw error value.

2. The control method according to claim 1, characterized in that: The control method further includes: The steering angle value of the mobile vehicle is obtained, and when the steering angle value is greater than a first reference value, steps (A), (B) and (C) are executed.

3. The control method according to claim 2, characterized in that: Step (C) comprises: calculating a first correction torque value based on the yaw error value; Calculating a second corrected torque value based on the steering angle value and the vehicle speed of the mobile vehicle; adjusting the torque output by the first drive element based on the sum of the first corrected torque value and the second corrected torque value weighted by weighting coefficients corresponding to the first drive element, and / or The torque output by the second drive element is adjusted based on a sum of the first correction torque value and the second correction torque value weighted by weighting coefficients corresponding to the second drive element.

4. The control method according to claim 3, characterized in that: Step (C) further comprises: Obtaining a first wheel slip difference value and a second wheel slip difference value of the mobile vehicle; When the first wheel slip difference is greater than a fourth reference value, a third correction torque value is calculated based on the first wheel slip difference, and the third correction torque value is further incorporated into the basis for adjusting the torque output by the first driving element, and / or When the second wheel slip difference is greater than a fourth reference value, a fourth correction torque value is calculated based on the second wheel slip difference, and the fourth correction torque value is further incorporated into the basis for adjusting the torque output by the second driving element.

5. The control method according to claim 2, characterized in that: The target yaw rate is a function of the steering angle value, a speed of the mobile vehicle, and at least one parameter specific to the mobile vehicle.

6. The control method according to claim 1, characterized in that: When the yaw error value is less than a third reference value, the method further includes: Obtaining a first wheel slip difference value and a second wheel slip difference value of the mobile vehicle; When the first wheel slip difference is greater than a fourth reference value, a third correction torque value is calculated based on the first wheel slip difference, and the torque output by the first driving element is adjusted based on the third correction torque value to reduce or eliminate the first wheel slip difference, and / or When the second wheel slip difference is greater than a fourth reference value, a fourth correction torque value is calculated based on the second wheel slip difference, and the torque output by the second driving element is adjusted based on the fourth correction torque value to reduce or eliminate the second wheel slip difference.

7. The control method according to claim 1, characterized in that: The first driving element and the second driving element drive the left rear wheel and the right rear wheel of the mobile vehicle respectively, and the target yaw rate is based on reducing or eliminating the inner wheel difference of the mobile vehicle when turning so as to maximize the overlap between the trajectories of the left rear wheel and the right rear wheel and the trajectories of the left front wheel and the right front wheel of the mobile vehicle.

8. The control method according to claim 2, characterized in that: The steering angle value is obtained from the steering angle of the wheel end of the mobile vehicle, the overall steering angle of the mobile vehicle, the steering angle of the steering wheel or the steering controller, the steering angle of the steering motor, or the stroke of the steering gear tie rod.

9. A control system for a mobile vehicle, characterized in that: The control system has at least one control unit, and the control system executes the control method according to any one of claims 1 to 8 through the at least one control unit.

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