A method and device for controlling angular acceleration limitation of a smart hub motor vehicle

Abstract

The present invention discloses an intelligent wheel hub motor automobile angular acceleration limiting control method, the process is as follows: calculate the speed difference value of each wheel hub motor, the total speed change of the whole vehicle, the normalized ratio of the speed change of each wheel hub motor, the maximum reference change angular acceleration of the whole vehicle center for each wheel hub motor, the theoretical reference angular acceleration of the speed change of the whole vehicle center, the reference angular acceleration of the speed change of the whole vehicle center, the usable angular acceleration of each wheel hub motor, the execution angular acceleration of each wheel hub motor, the speed increase and decrease of each wheel hub motor, the dynamic target speed of each wheel hub motor at the current moment, repeat the execution, and obtain the dynamic target speed of each wheel hub motor at the current moment is equal to the steady-state target speed of the wheel hub motor. The present invention also discloses an intelligent wheel hub motor automobile angular acceleration limiting control device. The present invention solves the problem of damage and reduced life of the wheel hub motor due to excessive angular acceleration exceeding the upper limit of the wheel hub motor angular velocity, and can be widely used in the field of automobile technology.

Description

Technical Field

[0001] The invention relates to automobile technology, and in particular to an intelligent wheel hub motor automobile angular acceleration limiting control method and device. Background Art

[0002] Wheel hub motor vehicles are an important development direction for electric vehicles. The speed and torque of each wheel hub motor can be dynamically controlled in real time according to the vehicle status. Wheel hub motor speed control is a control method for wheel hub motor vehicles. In the process of wheel hub motor speed control, the upper limit of the angular acceleration of the speed increase or decrease of each wheel hub motor is different. It is easy for the angular acceleration of the wheel hub motor to be too large, exceeding the upper limit of the angular velocity of the wheel hub motor, which will cause damage to the wheel hub motor and reduce its service life. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the above-mentioned background technology and to provide an intelligent wheel hub motor vehicle angular acceleration limiting control method and device, so as to solve the problem that the wheel hub motor angular acceleration of multiple wheel hub motor vehicles is too large, exceeding the upper limit capacity range of the wheel hub motor angular velocity, thereby causing damage to the wheel hub motor and reducing its service life.

[0004] The present invention provides an intelligent wheel hub motor vehicle angular acceleration limiting control method, the specific process of the method is as follows: based on the steady-state target speed of each wheel hub motor and the dynamic target speed of the wheel hub at the previous moment, the speed difference value of each wheel hub motor is calculated, the total speed change of the whole vehicle is calculated based on the speed difference value of the wheel hub motor, the normalized ratio of the speed change of each wheel hub motor is calculated based on the total speed change of the whole vehicle, the maximum reference change angular acceleration of the center of the vehicle for each wheel hub motor is calculated based on the maximum allowable change angular acceleration of each wheel hub motor and in combination with the Ackerman steering model, the theoretical reference angular acceleration of the center speed change of the whole vehicle is calculated based on the maximum reference change angular acceleration of the center of the vehicle for each wheel hub motor, and the theoretical reference angular acceleration of the center speed change of the whole vehicle is calculated based on the theoretical reference angular acceleration of the center speed change of the whole vehicle. The reference angular acceleration of the vehicle center speed change is calculated based on the acceleration. The available angular acceleration of each wheel hub motor is calculated based on the reference angular acceleration of the vehicle center speed change and combined with the Ackerman steering model. The execution angular acceleration of each wheel hub motor is calculated based on the available angular acceleration of each wheel hub motor and the normalized ratio of the speed change of each wheel hub motor. The speed increase or decrease of each wheel hub motor is calculated based on the execution angular acceleration of each wheel hub motor and the speed difference value of each wheel hub motor. The dynamic target speed of each wheel hub motor at the previous moment and the speed increase or decrease of each wheel hub motor are calculated. The above steps are repeated. The dynamic target speed of each wheel hub motor at the current moment obtained after cyclic execution is equal to the steady-state target speed of the wheel hub motor.

[0005] In the above technical solution, the specific process of the step of calculating the speed difference value of each hub motor based on the steady-state target speed of each hub motor and the dynamic target speed of the hub at the previous moment is as follows: the speed difference value of each hub motor is equal to the steady-state target speed of each hub motor minus the dynamic target speed at the previous moment; the above calculation formula is: ΔW(k) i =W i -W(k-1) i , where: ΔW(k) i ——The speed difference of the i-th wheel hub motor; W i ——The steady-state target speed of the i-th wheel hub motor; W(k-1) i ——The dynamic target speed of the i-th wheel hub motor at the previous moment; i——The number of the wheel hub motor, i∈[1,n], n is the total number of wheel hub motors; The specific process of the step of calculating the total change in vehicle speed based on the speed difference value of the wheel hub motor is as follows: The total change in vehicle speed is equal to the sum of the absolute values ​​of the speed difference values ​​of each wheel hub motor; The above calculation formula is: Where: ΔW(k) all ——The total change in vehicle speed.

[0006] In the above technical solution, the specific process of the step of calculating the normalized ratio of the speed change of each hub motor based on the total speed change of the whole vehicle is as follows: the normalized ratio of the speed change of each hub motor is equal to the absolute value of the speed difference value of each hub motor divided by the total speed change of the whole vehicle; the above calculation formula is: Among them: r(i) is the normalized ratio of the i-th wheel hub motor speed change; further, it can be known that: Further, it can be simplified to: Furthermore, combined with the steps of calculating the total change in vehicle speed based on the speed difference of the hub motor, it can be seen that: Furthermore, we can also know that: 0≤r(i)≤1.

[0007] In the above technical solution, the step of calculating the maximum reference change angular acceleration of the center of the vehicle for each hub motor based on the maximum allowable change angular acceleration of each hub motor and in combination with the Ackerman steering model includes two aspects: calculating the maximum reference increase angular acceleration of the center of the vehicle for each hub motor based on the maximum allowable increase angular acceleration of each hub motor and in combination with the Ackerman steering model; and calculating the maximum reference decrease angular acceleration of the center of the vehicle for each hub motor based on the maximum allowable decrease angular acceleration of each hub motor and in combination with the Ackerman steering model. The specific process is as follows: Maximum reference increase angular acceleration of each hub motor: The maximum reference increase angular acceleration of the center of the vehicle for each hub motor is equal to the ratio of the turning radius at the center of the vehicle to the turning radius of the wheel corresponding to its hub motor multiplied by the maximum allowable increase angular acceleration of its hub motor; Maximum reference decrease angular acceleration of each hub motor: The maximum reference decrease angular acceleration of the center of the vehicle for each hub motor is equal to the ratio of the turning radius at the center of the vehicle to the turning radius of the wheel corresponding to its hub motor multiplied by the maximum allowable decrease angular acceleration of its hub motor; the above calculation formula is: Among them: a(o,i) plusmax ——The maximum reference angular acceleration of the center of the vehicle for the i-th wheel hub motor; a(o,i) plusmax ——The maximum reference angular acceleration reduction of the center of the vehicle for the i-th wheel hub motor; R(i)——The turning radius of the wheel corresponding to the i-th wheel hub motor; R0——The turning radius at the center of the vehicle; a(i) minusmax ——The maximum permissible additional angular acceleration of the i-th wheel hub motor; a(i) minusmax ——The maximum allowable reduced angular acceleration of the i-th wheel hub motor; further, the magnitudes of R(i) and R0 are obtained by calculating the magnitude of the steering wheel steering angle in combination with the Ackerman steering model; the magnitude of the steering wheel steering angle is obtained by the steering angle sensor; further, a(i) plusmax 、a(i) minusmax It represents the maximum angular acceleration corresponding to the increase and decrease of the wheel hub motor speed. If this limit is exceeded, the wheel hub motor will be damaged and the service life will be reduced. Further, it can be known that:

[0008]

[0009] In the above technical scheme, the step of calculating the theoretical reference angular acceleration of the vehicle center speed change based on the maximum reference change angular acceleration of the vehicle center for each hub motor includes two aspects: calculating the theoretical reference angular acceleration of the vehicle center speed increase based on the maximum reference increase angular acceleration of the vehicle center for each hub motor and calculating the theoretical reference angular acceleration of the vehicle center speed decrease based on the maximum reference decrease angular acceleration of the vehicle center for each hub motor. The specific process is as follows: theoretical reference angular acceleration of vehicle center speed increase: the theoretical reference angular acceleration of vehicle center speed increase is equal to the minimum value of the maximum reference increase angular acceleration of the vehicle center for each hub motor, and satisfies that the speed difference value of its hub motor is greater than or equal to zero; theoretical reference angular acceleration of vehicle center speed decrease: the theoretical reference angular acceleration of vehicle center speed decrease is equal to the minimum value of the maximum reference decrease angular acceleration of the vehicle center for each hub motor, and satisfies that the speed difference value of its hub motor is less than zero; the above calculation formula is: Among them: a plusmax ——The theoretical reference angular acceleration of the vehicle center speed; a plusmax ——The vehicle center speed decreases the theoretical reference angular acceleration; further, it can be known that: The step of calculating the reference angular acceleration of the center speed change of the whole vehicle based on the theoretical reference angular acceleration of the center speed change of the whole vehicle is to calculate the reference angular acceleration of the center speed change of the whole vehicle based on the theoretical reference angular acceleration of the center speed increase of the whole vehicle and the theoretical reference angular acceleration of the center speed decrease of the whole vehicle. The specific process is as follows: the reference angular acceleration of the center speed change of the whole vehicle is equal to the smaller value of the theoretical reference angular acceleration of the center speed increase of the whole vehicle and the theoretical reference angular acceleration of the center speed decrease of the whole vehicle; the above calculation formula is: a plusminusmax =min(a plusmax ,a minusmax ), where: a plusminusmax ——The reference angular acceleration of the vehicle center speed change; further, it can be known that: Furthermore, according to the steps of calculating the theoretical reference angular acceleration of the center speed change of the whole vehicle based on the maximum reference angular acceleration of each wheel hub motor at the center of the whole vehicle, it can be known that:

[0010] In the above technical solution, the specific process of the step of calculating the usable angular acceleration of each hub motor based on the reference angular acceleration of the center speed change of the whole vehicle and in combination with the Ackerman steering model is as follows: the usable angular acceleration of each hub motor is equal to the ratio of the turning radius of the wheel corresponding to the hub motor to the turning radius at the center of the whole vehicle multiplied by the theoretical reference angular acceleration of the center speed reduction of the whole vehicle, and then multiplied by the reference angular acceleration of the center speed change of the whole vehicle; the above calculation formula is: Among them: a(i) plusminusmax——The angular acceleration available for the i-th wheel hub motor; further, according to the reference angular acceleration based on the change of the center speed of the whole vehicle and combined with the Ackerman steering model, the steps for calculating the available angular acceleration of each wheel hub motor are known: Furthermore, according to the steps of calculating the maximum reference angular acceleration of the center of the vehicle for each hub motor based on the maximum allowable angular acceleration of each hub motor and combining the Ackerman steering model, it can be known that:

[0011] In the above technical solution, the specific process of the step of calculating the execution angular acceleration of each hub motor based on the usable angular acceleration of each hub motor and the normalized ratio of the speed change of each hub motor is as follows: the execution angular acceleration of each hub motor is equal to the usable angular acceleration of each hub motor multiplied by the normalized ratio of the speed change of its hub motor; the above calculation formula is: a(i) plusminus =a(i) plusminusmax *r(i)where: a(i) plusminus ——The i-th wheel hub motor performs angular acceleration; further, combined with the step of calculating the normalized ratio of the speed change of each wheel hub motor based on the total speed change of the whole vehicle, it can be known that: a(i) plusminus ≤a(i) plusminusmax ; According to the reference angular acceleration based on the change of the center speed of the whole vehicle and combined with the Ackerman steering model, the steps for calculating the angular acceleration that can be used by each hub motor are as follows: It can be seen that the angular acceleration executed by each hub motor is not only less than or equal to the maximum allowable increased angular acceleration of the hub motor, but also less than or equal to the maximum allowable decreased angular acceleration of the hub motor. This avoids the problem of angular acceleration exceeding its capacity due to drastic changes in the speed of each hub motor, avoids hub damage and reduced service life, and improves the service life and reliability of each hub motor.

[0012] In the above technical solution, the step of calculating the speed increase or decrease of each hub motor based on the execution angular acceleration of each hub motor and the speed difference value of each hub motor includes the judgment results of the two cases that the speed difference value of the hub motor is greater than or equal to zero and the speed difference value of the hub motor is less than zero. The specific process is as follows: the speed difference value of the hub motor is greater than or equal to zero: if the speed difference value of the hub motor is greater than or equal to zero, then the speed increase or decrease of the hub motor is equal to the execution angular acceleration of the hub motor multiplied by the task execution interval period; the speed difference value of the hub motor is less than zero: if the speed difference value of the hub motor is less than zero, then the speed increase or decrease of the hub motor is equal to the opposite of the execution angular acceleration of the hub motor multiplied by the task execution interval period; the above calculation formula is: Where: ΔW1(k) i ——the speed increase or decrease of the i-th wheel hub motor; Δt——the task execution interval period.

[0013] In the above technical solution, the specific process of the step of calculating the dynamic target speed of each hub motor at the current moment based on the dynamic target speed of each hub motor at the previous moment and the speed increase or decrease of each hub motor is as follows: the dynamic target speed of each hub motor at the current moment is equal to the dynamic target speed of the hub motor at the previous moment plus the speed increase or decrease of the hub motor; the above calculation formula is: W(k) i =W(k-1) i +ΔW1(k) i , where: W(k) i ——The dynamic target speed of the i-th wheel hub motor at the previous moment; further, the dynamic target speed of each wheel hub motor at the previous moment is updated to the dynamic target speed of its wheel hub motor at the current moment, that is, W(k-1) i =W(k) i ; Repeat the above steps, and the specific process of obtaining the dynamic target speed of each hub motor at the current moment equal to the steady-state target speed of the hub motor after cyclic execution is as follows: repeat the steps of calculating the speed difference value of each hub motor based on the steady-state target speed of each hub motor and the dynamic target speed of the hub at the previous moment according to the time interval as the task execution interval period, calculating the total amount of vehicle speed change based on the speed difference value of the hub motor, calculating the normalized proportion of the speed change of each hub motor based on the total amount of vehicle speed change, calculating the maximum reference angular acceleration of the center of the vehicle for each hub motor based on the maximum allowable change angular acceleration of each hub motor and combined with the Ackerman steering model, and calculating the center speed change of the vehicle based on the maximum reference angular acceleration of the center of the vehicle for each hub motor. Theoretical reference angular acceleration step, step of calculating the reference angular acceleration of the center speed change of the whole vehicle based on the theoretical reference angular acceleration of the center speed change of the whole vehicle, step of calculating the usable angular acceleration of each hub motor based on the reference angular acceleration of the center speed change of the whole vehicle and combined with the Ackerman steering model, step of calculating the execution angular acceleration of each hub motor based on the usable angular acceleration of each hub motor and the normalized ratio of the speed change of each hub motor, step of calculating the speed increase or decrease of each hub motor based on the execution angular acceleration of each hub motor and the speed difference value of each hub motor, and step of calculating the dynamic target speed of each hub motor at the current moment based on the dynamic target speed of each hub motor at the previous moment and the speed increase or decrease of each hub motor. After the cycle, the dynamic target speed of each hub motor at the current moment is equal to its steady-state target speed of the hub motor.

[0014] The present invention also provides an intelligent wheel hub motor vehicle angular acceleration limiting control device, which has a computer program, and the computer program can execute the intelligent wheel hub motor vehicle angular acceleration limiting control method.

[0015] The intelligent wheel hub motor vehicle angular acceleration limiting control method and device of the present invention have the following beneficial effects:

[0016] The angular acceleration executed by each hub motor is both less than or equal to the maximum allowable increasing angular acceleration of the hub motor and less than or equal to the maximum allowable decreasing angular acceleration of the hub motor, thereby avoiding the problem that the angular acceleration of each hub motor exceeds its capacity due to drastic changes in its speed, thereby damaging the hub and reducing its service life, thereby improving the service life and reliability of each hub motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall idea of ​​the intelligent wheel hub motor vehicle angular acceleration limiting control method of the present invention;

[0018] Figure 2 It is a schematic diagram of specific steps of the intelligent wheel hub motor vehicle angular acceleration limiting control method of the present invention;

[0019] Figure 3 It is a structural schematic diagram of the angular acceleration limiting control device of the intelligent wheel hub motor vehicle of the present invention. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments, but the embodiments should not be construed as limiting the present invention.

[0021] See also Figure 1 The present invention provides a method for limiting the angular acceleration of an intelligent wheel hub motor vehicle. The overall idea of ​​the method is as follows:

[0022] The speed difference of each wheel hub motor is calculated based on the steady-state target speed of each wheel hub motor and the dynamic target speed of the wheel hub at the previous moment. The total speed change of the whole vehicle is calculated based on the speed difference of the wheel hub motor. The normalized ratio of the speed change of each wheel hub motor is calculated based on the total speed change of the whole vehicle. The maximum reference angular acceleration of the center of the vehicle for each wheel hub motor is calculated based on the maximum allowable angular acceleration of each wheel hub motor and combined with the Ackerman steering model. The theoretical reference angular acceleration of the center speed change of the vehicle is calculated based on the maximum reference angular acceleration of the center of the vehicle for each wheel hub motor. The reference angular acceleration of the center speed change of the vehicle is calculated based on the theoretical reference angular acceleration of the center speed change of the vehicle. The available angular acceleration of each wheel hub motor is calculated based on the reference angular acceleration of the vehicle center speed change and the Ackerman steering model; the execution angular acceleration of each wheel hub motor is calculated based on the available angular acceleration of each wheel hub motor and the normalized ratio of the speed change of each wheel hub motor; the speed increase or decrease of each wheel hub motor is calculated based on the execution angular acceleration of each wheel hub motor and the speed difference value of each wheel hub motor; the dynamic target speed of each wheel hub motor at the current moment is calculated based on the dynamic target speed of each wheel hub motor at the previous moment and the speed increase or decrease of each wheel hub motor; the aforementioned steps are repeated, and the dynamic target speed of each wheel hub motor at the current moment obtained after cyclic execution is equal to the steady-state target speed of the wheel hub motor.

[0023] See also Figure 2 The specific steps of the intelligent wheel hub motor vehicle angular acceleration limiting control method of the present invention are as follows:

[0024] Step 1: Calculate the speed difference value of each hub motor based on the steady-state target speed of each hub motor and its dynamic target speed at the previous moment. The speed difference value of each hub motor is equal to the steady-state target speed of each hub motor minus its dynamic target speed at the previous moment.

[0025] The above calculation formula is:

[0026] ΔW(k) i =W i -W(k-1) i

[0027] Where: ΔW(k) i ——The speed difference of the i-th wheel hub motor; W i ——The steady-state target speed of the i-th wheel hub motor; W(k-1) i ——The dynamic target speed of the i-th hub motor at the previous moment; i——The number of the hub motor, i∈[1,n], n is the total number of hub motors.

[0028] Step 2: Calculate the total vehicle speed change based on the speed difference of the wheel hub motors. The total vehicle speed change is equal to the sum of the absolute values ​​of the speed difference of each wheel hub motor.

[0029] The above calculation formula is:

[0030]

[0031] Where: ΔW(k) all ——The total change in vehicle speed.

[0032] Step 3: Calculate the normalized ratio of the speed change of each wheel hub motor based on the total speed change of the vehicle.

[0033] The normalized ratio of the speed change of each hub motor is equal to the absolute value of the speed difference of each hub motor divided by the total speed change of the whole vehicle.

[0034] The above calculation formula is:

[0035]

[0036] Where: r(i) – the normalized ratio of the i-th wheel hub motor speed change;

[0037] Further, we know that:

[0038]

[0039] Further, it can be simplified to:

[0040]

[0041] Further, combined with step 2, we can know that:

[0042]

[0043] Furthermore, we can know that:

[0044] 0≤r(i)≤1

[0045] Step 4: including calculating the maximum reference increased angular acceleration of the center of the vehicle for each wheel hub motor based on the maximum allowable increased angular acceleration of each wheel hub motor in combination with the Ackerman steering model, and calculating the maximum reference decreased angular acceleration of the center of the vehicle for each wheel hub motor based on the maximum allowable decreased angular acceleration of each wheel hub motor in combination with the Ackerman steering model.

[0046] The maximum reference increased angular acceleration of each wheel hub motor: The maximum reference increased angular acceleration of the center of the vehicle for each wheel hub motor is equal to the ratio of the turning radius at the center of the vehicle to the turning radius of the wheel corresponding to its wheel hub motor multiplied by the maximum allowable increased angular acceleration of its wheel hub motor;

[0047] Maximum reference reduced angular acceleration of each hub motor: The maximum reference reduced angular acceleration of the center of the vehicle for each hub motor is equal to the ratio of the turning radius at the center of the vehicle to the turning radius of the wheel corresponding to its hub motor multiplied by the maximum allowable reduced angular acceleration of its hub motor.

[0048] The above calculation formula is:

[0049]

[0050] Among them: a(o,i) plusmax ——The maximum reference angular acceleration of the center of the vehicle for the i-th wheel hub motor; a(o,i) plusmax ——The maximum reference angular acceleration reduction of the center of the vehicle for the i-th wheel hub motor; R(i)——The turning radius of the wheel corresponding to the i-th wheel hub motor; R0——The turning radius at the center of the vehicle; a(i) minusmax ——The maximum permissible additional angular acceleration of the i-th wheel hub motor; a(i) minismax ——The maximum allowed reduced angular acceleration of the ith wheel hub motor.

[0051] Furthermore, the magnitudes of R(i) and R0 are obtained by calculating the magnitude of the steering wheel steering angle in combination with the Ackerman steering model; the magnitude of the steering wheel steering angle is obtained by a steering angle sensor.

[0052] Furthermore, a(i) plusmax 、a(i) minusmax It represents the maximum angular acceleration corresponding to the increase and decrease of the hub motor speed. If this limit is exceeded, the hub motor will be damaged and its service life will be reduced.

[0053] Further, we know that:

[0054]

[0055] Step 5: including calculating the theoretical reference angular acceleration for increasing the center speed of the vehicle based on the maximum reference angular acceleration increase of the center of the vehicle for each hub motor, and calculating the theoretical reference angular acceleration for decreasing the center speed of the vehicle based on the maximum reference angular acceleration decrease of the center of the vehicle for each hub motor.

[0056] The theoretical reference angular acceleration of the vehicle center speed increase: The theoretical reference angular acceleration of the vehicle center speed increase is equal to the minimum value of the maximum reference angular acceleration of the vehicle center for each wheel hub motor, and the speed difference value of the wheel hub motor is greater than or equal to zero;

[0057] Theoretical reference angular acceleration for reducing the center speed of the vehicle: The theoretical reference angular acceleration for reducing the center speed of the vehicle is equal to the minimum value of the maximum reference angular acceleration of the center of the vehicle for each wheel hub motor, and the speed difference value of the wheel hub motor is less than zero.

[0058] The above calculation formula is:

[0059]

[0060] Among them: a plusmax ——The theoretical reference angular acceleration of the vehicle center speed; a plusmax ——The center speed of the vehicle decreases by the theoretical reference angular acceleration.

[0061] Further, we know that:

[0062]

[0063] Step 6: Calculate the reference angular acceleration of the vehicle center speed change based on the theoretical reference angular acceleration of the vehicle center speed increase and the theoretical reference angular acceleration of the vehicle center speed decrease.

[0064] The reference angular acceleration of the change in the center speed of the whole vehicle is equal to the smaller value of the theoretical reference angular acceleration of the increase in the center speed of the whole vehicle and the theoretical reference angular acceleration of the decrease in the center speed of the whole vehicle.

[0065] The above calculation formula is:

[0066] a plusminusmax =min(a plusmax,a minusmax )

[0067] Among them: a plusminusmax ——Reference angular acceleration of the vehicle’s center speed change.

[0068] Further, we know that:

[0069]

[0070] Further, according to step 5:

[0071]

[0072] Step 7: To ensure that the speed change of each wheel hub meets the Ackerman model of the vehicle, the available angular acceleration of each wheel hub motor is calculated based on the reference angular acceleration of the vehicle center speed change and combined with the Ackerman steering model.

[0073] The angular acceleration that can be used by each wheel hub motor is equal to the ratio of the turning radius of the wheel corresponding to the wheel hub motor to the turning radius at the center of the vehicle multiplied by the theoretical reference angular acceleration of the vehicle center speed reduction, and then multiplied by the reference angular acceleration of the vehicle center speed change. The calculation formula is:

[0074]

[0075] Among them: a(i) plusminusmax ——The i-th wheel hub motor can use angular acceleration.

[0076] Further, according to step 7:

[0077]

[0078] Further, according to step 4:

[0079]

[0080] Step 8: Calculate the execution angular acceleration of each wheel hub motor based on the available angular acceleration of each wheel hub motor and the normalized ratio of the speed change of each wheel hub motor.

[0081] The angular acceleration of each hub motor is equal to the normalized ratio of the available angular acceleration of each hub motor multiplied by its hub motor speed change.

[0082] The above calculation formula is:

[0083] a(i) plusminus =a(i) plusminusmax *r(i)

[0084] Among them: a(i) plusminus ——The i-th wheel hub motor performs angular acceleration.

[0085] Further, combined with step 3, we can know that:

[0086] a(i) plusminus ≤a(i) plusminusmax

[0087] According to step 7:

[0088]

[0089] It can be seen that the angular acceleration executed by each hub motor is not only less than or equal to the maximum allowable increased angular acceleration of the hub motor, but also less than or equal to the maximum allowable decreased angular acceleration of the hub motor. This avoids the problem of angular acceleration exceeding its capacity due to drastic changes in the speed of each hub motor, avoids hub damage and reduced service life, and improves the service life and reliability of each hub motor.

[0090] Step 9: Calculating the increase or decrease in the speed of each hub motor based on the angular acceleration of each hub motor and the speed difference of each hub motor includes judging the results of the two cases: the speed difference of the hub motor is greater than or equal to zero and the speed difference of the hub motor is less than zero. The specific process is as follows:

[0091] The speed difference of the hub motor is greater than or equal to zero: if the speed difference of the hub motor is greater than or equal to zero, the increase or decrease in the speed of the hub motor is equal to the execution angular acceleration of the hub motor multiplied by the task execution interval period;

[0092] The speed difference of the hub motor is less than zero: If the speed difference of the hub motor is less than zero, the increase or decrease of the hub motor speed is equal to the negative number of the hub motor execution angular acceleration multiplied by the task execution interval period. The calculation formula is:

[0093]

[0094] Where: ΔW1(k) i ——the speed increase or decrease of the i-th wheel hub motor; Δt——the task execution interval period.

[0095] Step 10: Calculate the dynamic target speed of each hub motor at the current moment based on the dynamic target speed of each hub motor at the previous moment and the speed increase or decrease of each hub motor.

[0096] The dynamic target speed of each hub motor at the current moment is equal to the dynamic target speed of the hub motor at the previous moment plus the speed increase or decrease of the hub motor;

[0097] The above calculation formula is:

[0098] W(k) i =W(k-1)i +ΔW1(k) i

[0099] Where: W(k) i ——The dynamic target speed of the i-th wheel hub motor at the previous moment.

[0100] Further, the dynamic target speed of each hub motor at the previous moment is updated to the dynamic target speed of the hub motor at the current moment, that is, W(k-1) i =W(k) i ;

[0101] Step 11: Repeat steps 1 to 10 according to the time interval as the task execution interval period. After a cycle, the dynamic target speed of each hub motor at the current moment is equal to the steady-state target speed of the hub motor.

[0102] See also Figure 3 The intelligent wheel hub motor vehicle angular acceleration limiting control device of the present invention comprises the following parts:

[0103] Speed ​​difference value module: calculates the speed difference value of each wheel hub motor based on the steady-state target speed of each wheel hub motor and the dynamic target speed of the wheel hub at the previous moment;

[0104] Speed ​​change total amount module: calculates the total speed change of the vehicle based on the speed difference value of the hub motor;

[0105] Normalization ratio module: calculates the normalization ratio of each wheel hub motor speed change based on the total speed change of the vehicle;

[0106] Maximum reference angular acceleration module: Calculates the maximum reference angular acceleration of the vehicle center for each wheel hub motor based on the maximum allowable angular acceleration of each wheel hub motor and in combination with the Ackerman steering model;

[0107] Theoretical reference angular acceleration module: Calculates the theoretical reference angular acceleration of the vehicle center speed change based on the maximum reference angular acceleration of each wheel hub motor at the center of the vehicle;

[0108] Speed ​​change reference angular acceleration module: calculates the reference angular acceleration of the center speed change of the vehicle based on the theoretical reference angular acceleration of the center speed change of the vehicle;

[0109] Available angular acceleration module: Calculates the available angular acceleration of each wheel hub motor based on the reference angular acceleration of the vehicle center speed change and the Ackerman steering model;

[0110] Execution angular acceleration module: Calculates the execution angular acceleration of each hub motor based on the available angular acceleration of each hub motor and the normalized ratio of the speed change of each hub motor;

[0111] Speed ​​increase / decrease module: calculates the speed increase / decrease of each hub motor based on the angular acceleration of each hub motor and the speed difference of each hub motor;

[0112] Current moment dynamic target speed module: calculates the current moment dynamic target speed of each wheel hub motor based on the previous moment dynamic target speed of each wheel hub motor and the speed increase or decrease of each wheel hub motor;

[0113] Steady-state target speed module: Repeat the above steps, and the dynamic target speed of each hub motor at the current moment obtained after cyclic execution is equal to the steady-state target speed of the hub motor.

[0114] The technical effects of the intelligent wheel hub motor vehicle angular acceleration limiting control method and device of the present invention are as follows:

[0115] The angular acceleration executed by each hub motor is both less than or equal to the maximum allowable increasing angular acceleration of the hub motor and less than or equal to the maximum allowable decreasing angular acceleration of the hub motor, thereby avoiding the problem that the angular acceleration of each hub motor exceeds its capacity due to drastic changes in its speed, thereby damaging the hub and reducing its service life, thereby improving the service life and reliability of each hub motor.

[0116] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

[0117] The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A method for limiting angular acceleration of a smart hub motor vehicle, characterized in that: The specific steps of this method are as follows: Calculate the speed difference value of each wheel hub motor based on the steady-state target speed of each wheel hub motor and the dynamic target speed of the wheel hub at the previous moment; Calculate the total vehicle speed change based on the speed difference of the wheel hub motor; Calculate the normalized ratio of the speed change of each wheel hub motor based on the total speed change of the vehicle; Based on the maximum allowable angular acceleration of each wheel hub motor and combined with the Ackerman steering model, the maximum reference angular acceleration of the center of the vehicle for each wheel hub motor is calculated; The theoretical reference angular acceleration of the vehicle center speed change is calculated based on the maximum reference angular acceleration of the vehicle center for each wheel hub motor; Calculate the reference angular acceleration of the center speed change of the whole vehicle based on the theoretical reference angular acceleration of the center speed change of the whole vehicle; The available angular acceleration of each wheel hub motor is calculated based on the reference angular acceleration of the vehicle center speed change and combined with the Ackerman steering model; Calculate the execution angular acceleration of each hub motor based on the available angular acceleration of each hub motor and the normalized ratio of the speed change of each hub motor; Calculating the increase or decrease in the speed of each hub motor based on the angular acceleration of each hub motor and the speed difference value of each hub motor; Calculate the dynamic target speed of each wheel hub motor at the current moment based on the dynamic target speed of each wheel hub motor at the previous moment and the speed increase or decrease of each wheel hub motor; Repeat the above steps, and the dynamic target speed of each hub motor at the current moment obtained after the cyclic execution is equal to the steady-state target speed of the hub motor.

2. The intelligent wheel hub motor vehicle angular acceleration limiting control method according to claim 1 is characterized in that: The specific process of the step of calculating the speed difference value of each wheel hub motor based on the steady-state target speed of each wheel hub motor and the dynamic target speed of the wheel hub at the previous moment is as follows: The speed difference of each hub motor is equal to the steady-state target speed of each hub motor minus its dynamic target speed at the previous moment; The above calculation formula is: in: ——No. The speed difference of the wheel hub motors; ——No. Steady-state target speed of each wheel motor; ——No. The dynamic target speed of each wheel hub motor at the last moment; ——The number of the hub motor, , is the total number of hub motors; The specific process of the step of calculating the total amount of vehicle speed change based on the speed difference value of the hub motor is as follows: The total change in vehicle speed is equal to the sum of the absolute values ​​of the speed differences of each wheel hub motor; The above calculation formula is: in: ——The total change in vehicle speed.

3. The intelligent wheel hub motor vehicle angular acceleration limiting control method according to claim 2 is characterized in that: The specific process of the step of calculating the normalized ratio of the speed change of each wheel hub motor based on the total speed change of the whole vehicle is as follows: The normalized ratio of the speed change of each wheel hub motor is equal to the absolute value of the speed difference of each wheel hub motor divided by the total speed change of the whole vehicle; The above calculation formula is: in: ——No. Normalized ratio of the speed change of each wheel hub motor; Further, we know that: Further, it can be simplified to: Furthermore, combined with the steps of calculating the total change in vehicle speed based on the speed difference of the hub motor, it can be seen that: Furthermore, we can know that: 。 4. The intelligent wheel hub motor vehicle angular acceleration limiting control method according to claim 3 is characterized in that: The step of calculating the maximum reference change angular acceleration of the center of the vehicle for each hub motor based on the maximum allowable change angular acceleration of each hub motor in combination with the Ackerman steering model includes two aspects: calculating the maximum reference increase angular acceleration of the center of the vehicle for each hub motor based on the maximum allowable increase angular acceleration of each hub motor in combination with the Ackerman steering model and calculating the maximum reference decrease angular acceleration of the center of the vehicle for each hub motor based on the maximum allowable decrease angular acceleration of each hub motor in combination with the Ackerman steering model. The specific process is as follows: The maximum reference increased angular acceleration of each wheel hub motor: The maximum reference increased angular acceleration of the center of the vehicle for each wheel hub motor is equal to the ratio of the turning radius at the center of the vehicle to the turning radius of the wheel corresponding to its wheel hub motor multiplied by the maximum allowable increased angular acceleration of its wheel hub motor; The maximum reference reduced angular acceleration of each wheel hub motor: The maximum reference reduced angular acceleration of the center of the vehicle for each wheel hub motor is equal to the ratio of the turning radius at the center of the vehicle to the turning radius of the wheel corresponding to its wheel hub motor multiplied by the maximum allowable reduced angular acceleration of its wheel hub motor; The above calculation formula is: in: ——The vehicle center is for the The maximum reference increase of the angular acceleration of the wheel hub motor; ——The vehicle center is for the The maximum reference reduction angular acceleration of each wheel hub motor; ——No. The turning radius of the wheel corresponding to each wheel hub motor; ——Turning radius at the center of the vehicle; ——No. The maximum permissible increase in angular acceleration for each wheel hub motor; ——No. The maximum permissible reduction in angular acceleration of each wheel hub motor; Furthermore, , The size of is obtained by calculating the steering wheel steering angle in combination with the Ackerman steering model; the steering wheel steering angle is obtained by the steering angle sensor; Furthermore, , It represents the maximum angular acceleration corresponding to the increase and decrease of the wheel hub motor speed. If this limit is exceeded, the wheel hub motor will be damaged and its service life will be reduced. Further, we know that: 。 5. The intelligent wheel hub motor vehicle angular acceleration limiting control method according to claim 4 is characterized in that: The step of calculating the theoretical reference angular acceleration of the vehicle center speed change based on the maximum reference change angular acceleration of the vehicle center for each hub motor includes two aspects: calculating the theoretical reference angular acceleration of the vehicle center speed increase based on the maximum reference increase angular acceleration of the vehicle center for each hub motor and calculating the theoretical reference angular acceleration of the vehicle center speed decrease based on the maximum reference decrease angular acceleration of the vehicle center for each hub motor. The specific process is as follows: The theoretical reference angular acceleration of the vehicle center speed increase: The theoretical reference angular acceleration of the vehicle center speed increase is equal to the minimum value of the maximum reference angular acceleration of the vehicle center for each wheel hub motor, and the speed difference value of the wheel hub motor is greater than or equal to zero; Theoretical reference angular acceleration of vehicle center speed reduction: Theoretical reference angular acceleration of vehicle center speed reduction is equal to the minimum value of the maximum reference angular acceleration of the vehicle center for each wheel hub motor, and the speed difference value of the wheel hub motor is less than zero; The above calculation formula is: in: ——The vehicle center speed increases by the theoretical reference angular acceleration; ——The theoretical reference angular acceleration of the vehicle center speed reduction; Further, we know that: The step of calculating the reference angular acceleration of the center speed change of the whole vehicle based on the theoretical reference angular acceleration of the center speed change of the whole vehicle is to calculate the reference angular acceleration of the center speed change of the whole vehicle based on the theoretical reference angular acceleration of the center speed increase of the whole vehicle and the theoretical reference angular acceleration of the center speed decrease of the whole vehicle. The specific process is as follows: The reference angular acceleration of the vehicle center speed change is equal to the smaller value of the theoretical reference angular acceleration of the vehicle center speed increase and the theoretical reference angular acceleration of the vehicle center speed decrease; The above calculation formula is: in: ——Reference angular acceleration of vehicle center speed change; Further, we know that: Furthermore, according to the steps of calculating the theoretical reference angular acceleration of the center speed change of the whole vehicle based on the maximum reference angular acceleration of each wheel hub motor at the center of the whole vehicle, it can be known that: 。 6. The intelligent wheel hub motor vehicle angular acceleration limiting control method according to claim 5 is characterized in that: The specific process of calculating the usable angular acceleration of each wheel hub motor based on the reference angular acceleration of the vehicle center speed change and the Ackerman steering model is as follows: Each wheel hub motor can use an angular acceleration equal to the ratio of the turning radius of the wheel corresponding to the wheel hub motor to the turning radius at the center of the vehicle multiplied by the theoretical reference angular acceleration of the vehicle center speed reduction, multiplied by the reference angular acceleration of the vehicle center speed change; The above calculation formula is: in: ——No. Each wheel hub motor can use angular acceleration; Furthermore, according to the reference angular acceleration based on the change of the center speed of the whole vehicle and combined with the Ackerman steering model, the steps for calculating the angular acceleration that can be used for each hub motor are as follows: Furthermore, according to the steps of calculating the maximum reference angular acceleration of the center of the vehicle for each hub motor based on the maximum allowable angular acceleration of each hub motor and combining the Ackerman steering model, it can be known that: 。 7. The intelligent wheel hub motor vehicle angular acceleration limiting control method according to claim 6 is characterized in that: The specific process of calculating the angular acceleration of each hub motor based on the angular acceleration available to each hub motor and the normalized ratio of the speed change of each hub motor is as follows: The execution angular acceleration of each hub motor is equal to the usable angular acceleration of each hub motor multiplied by the normalized ratio of its hub motor speed change; The above calculation formula is: in: ——No. The wheel hub motor performs angular acceleration; Furthermore, combined with the step of calculating the normalized ratio of the speed change of each wheel hub motor based on the total speed change of the whole vehicle, it can be known that: According to the reference angular acceleration based on the change of the center speed of the vehicle and the Ackerman steering model, the steps for calculating the angular acceleration that can be used by each wheel hub motor are as follows: It can be seen that the angular acceleration executed by each hub motor is not only less than or equal to the maximum allowable increased angular acceleration of the hub motor, but also less than or equal to the maximum allowable decreased angular acceleration of the hub motor. This avoids the problem of angular acceleration exceeding its capacity due to drastic changes in the speed of each hub motor, avoids hub damage and reduced service life, and improves the service life and reliability of each hub motor.

8. The intelligent wheel hub motor vehicle angular acceleration limiting control method according to claim 7 is characterized in that: The step of calculating the increase or decrease of the speed of each hub motor based on the angular acceleration of each hub motor and the speed difference of each hub motor includes two situations where the judgment results are that the speed difference of the hub motor is greater than or equal to zero and the speed difference of the hub motor is less than zero. The specific process is as follows: The speed difference of the hub motor is greater than or equal to zero: if the speed difference of the hub motor is greater than or equal to zero, the speed increase or decrease of the hub motor is equal to the hub motor execution angular acceleration multiplied by the task execution interval period; The speed difference value of the hub motor is less than zero: if the speed difference value of the hub motor is less than zero, the speed increase or decrease of the hub motor is equal to the negative number of the hub motor execution angular acceleration multiplied by the task execution interval period; The above calculation formula is: in: ——No. The speed increase or decrease of each wheel hub motor; ——Task execution interval period.

9. The intelligent wheel hub motor vehicle angular acceleration limiting control method according to claim 8, characterized in that: The specific process of calculating the dynamic target speed of each wheel hub motor at the current moment based on the dynamic target speed of each wheel hub motor at the previous moment and the speed increase or decrease of each wheel hub motor is as follows: The dynamic target speed of each hub motor at the current moment is equal to the dynamic target speed of the hub motor at the previous moment plus the speed increase or decrease of the hub motor; The above calculation formula is: in: ——No. The dynamic target speed of each wheel hub motor at the current moment; Furthermore, the dynamic target speed of each hub motor at the previous moment is updated to the dynamic target speed of the hub motor at the current moment, that is, ; Repeat the above steps, and the specific process of obtaining the dynamic target speed of each hub motor at the current moment equal to the steady-state target speed of the hub motor after cyclic execution is as follows: Repeat the steps of calculating the speed difference of each wheel hub motor based on the steady-state target speed of each wheel hub motor and the dynamic target speed of the wheel hub at the previous moment according to the time interval as the task execution interval period, calculating the total speed change of the whole vehicle based on the speed difference of the wheel hub motor, calculating the normalized proportion of the speed change of each wheel hub motor based on the total speed change of the whole vehicle, calculating the maximum reference angular acceleration of the center of the vehicle for each wheel hub motor based on the maximum allowable angular acceleration of each wheel hub motor and in combination with the Ackerman steering model, calculating the theoretical reference angular acceleration of the center speed change of the vehicle based on the maximum reference angular acceleration of the center of the vehicle for each wheel hub motor, and calculating the normalized proportion of the speed change of each wheel hub motor based on the total speed change of the whole vehicle. The steps of calculating the reference angular acceleration of the center speed change of the whole vehicle, calculating the available angular acceleration of each hub motor based on the reference angular acceleration of the center speed change of the whole vehicle and combining the Ackerman steering model, calculating the execution angular acceleration of each hub motor based on the available angular acceleration of each hub motor and the normalized ratio of the speed change of each hub motor, calculating the speed increase or decrease of each hub motor based on the execution angular acceleration of each hub motor and the speed difference of each hub motor, and calculating the dynamic target speed of each hub motor at the current moment based on the dynamic target speed of each hub motor at the previous moment and the speed increase or decrease of each hub motor. After the cycle, the dynamic target speed of each hub motor at the current moment is equal to its steady-state target speed of the hub motor.

10. An intelligent wheel hub motor vehicle angular acceleration limiting control device, having a computer program, characterized in that: The computer program can execute the intelligent wheel hub motor vehicle angular acceleration limiting control method as described in any one of claims 1 to 9.

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