Multi-wheel independent steering assist tracking control method and device

Abstract

The application discloses a kind of multi-wheel independent steering assist force tracking control methods, process as follows: the target assist force of each steering wheel is calculated respectively, the maximum value of unit time vehicle assist force change, the total assist force change of vehicle, the maximum value of assist force collaborative change, the total amount of the absolute proportion of the relative difference of instantaneous assist force, the change multiple of the maximum allowable change of assist force, the scaling factor of the total amount of the absolute proportion of the relative difference of instantaneous assist force, the maximum value of the scaling factor of the total amount of the absolute proportion of the relative difference of instantaneous assist force, instantaneous assist force change tracking coefficient, assist force change tracking amount, assist force change tracking amount and current time instantaneous target assist force.The application also discloses a kind of multi-wheel independent steering assist force tracking control device.The application can solve the problem that each steering wheel reaches target assist force time is different, causes each steering wheel steering mechanical damage and working life reduction caused by assist force change too fast, can be widely applied in vehicle control field.

Description

Technical Field

[0001] This invention relates to the field of vehicle control, and in particular to a multi-wheel independent steering assist tracking control method and device. Background Technology

[0002] To improve vehicle passability, the steering angle of each steering wheel is controlled independently. Because there are many steering wheels and each wheel bears a different load, the amount of steering assistance required for each wheel also varies. Furthermore, the changes in steering assistance during the tracking control process are not uniform, leading to different times to reach the target assistance level. Additionally, excessively rapid changes in assistance can easily cause damage to the steering mechanism of each wheel and reduce its service life. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the above-mentioned background technology and provide a multi-wheel independent steering assist tracking control method and device, which can solve the problem that the steering assist increases or decreases inconsistently during the tracking control process, resulting in different times to reach the target assist and damage to the steering machinery of each steering wheel and reduced service life due to excessively rapid changes in assist.

[0004] This invention provides a multi-wheel independent steering assist tracking control method, the specific process of which is as follows: Calculate the relative difference between the target assist of each steering wheel and the instantaneous target assist of that steering wheel at the previous moment; obtain the maximum value of the overall vehicle assist change per unit time; calculate the total vehicle assist change; calculate the maximum value of the coordinated change of the overall vehicle assist per unit time; calculate the absolute percentage of the total change in the relative difference of the instantaneous assist of each steering wheel; calculate the change multiple of the maximum allowable change in assist of each steering wheel per unit time; calculate the scaling factor of the absolute percentage of the total change in the relative difference of the instantaneous assist of each steering wheel; calculate the maximum value of the scaling factor of the absolute percentage of the total change in the relative difference of the instantaneous assist of each steering wheel; calculate the tracking coefficient of the instantaneous assist change of each steering wheel; calculate the tracking amount of the instantaneous assist change of each steering wheel; and calculate the instantaneous target assist of each steering wheel at the current moment based on the tracking amount of the instantaneous assist change of each steering wheel and the instantaneous target assist of each steering wheel at the previous moment.

[0005] In the above technical solution, the specific process of calculating the relative difference between the target assist of each steering wheel and its instantaneous target assist at the previous moment is as follows: Calculate the relative difference between the target assist to be performed on each steering wheel and the instantaneous target assist of that steering wheel at the previous moment: ,in: ——No. The target assistance to be performed by each steering wheel; ——No. The instantaneous target assist of each steering wheel at a given moment; ——No. The relative difference in instantaneous assist to each steering wheel. —Steering wheel number, , The total number of steering wheels; the specific process of obtaining the maximum value of the change in vehicle power assist per unit time is as follows: Calculation principle of the maximum value of the change in vehicle power assist per unit time: The maximum increase in vehicle power assist per unit time is equal to the minimum allowable increase in power assist per unit time for all steering wheels that should have an instantaneous target power assist; the maximum decrease in vehicle power assist per unit time is equal to the minimum allowable decrease in power assist per unit time for all steering wheels that should have an instantaneous target power assist; the calculation formula is:

[0006] ,in: —The maximum increase in vehicle assist per unit time; —The maximum decrease in the overall vehicle steering assist within a unit of time; ——No. The maximum permissible increase in power assist per unit time for each steering wheel; ——No. The maximum permissible decrease in power assist for each steering wheel per unit time; the maximum increase and the maximum decrease in power assist for the entire vehicle per unit time satisfy the following characteristics: the maximum increase in power assist for the entire vehicle per unit time is not greater than the maximum permissible increase in power assist for each steering wheel per unit time, and the maximum decrease in power assist for the entire vehicle per unit time is not greater than the maximum permissible decrease in power assist for each steering wheel per unit time; the calculation formula is:

[0007] .

[0008] In the above technical solution, the calculation of the total vehicle assist change includes calculating the increase and decrease of the total vehicle assist. The specific process is as follows: Calculation of the increase in total vehicle assist: The increase in total vehicle assist is equal to the sum of the relative differences in the instantaneous assist of all steering wheels for which the instantaneous target assist should be increased; Calculation of the decrease in total vehicle assist: The decrease in total vehicle assist is equal to the sum of the absolute values ​​of the relative differences in the instantaneous assist of all steering wheels for which the instantaneous target assist should be decreased; The calculation formula is: The specific process for calculating the maximum value of the coordinated change in vehicle power steering within a unit time is as follows: The maximum value of the coordinated change in vehicle power steering within a unit time satisfies the following conditions: the maximum increase in coordinated vehicle power steering within a unit time is less than or equal to the corresponding maximum increase in vehicle power steering within a unit time, and the maximum decrease in coordinated vehicle power steering within a unit time is less than or equal to the corresponding maximum decrease in vehicle power steering within a unit time; and the ratio of the maximum increase in coordinated vehicle power steering within a unit time to the maximum decrease in coordinated vehicle power steering within a unit time is equal to the ratio of the total increase in vehicle power steering assist to the total decrease in vehicle power steering assist; the calculation formula is:

[0009] in: —The maximum increase in vehicle power assist coordination per unit time; —The maximum decrease in the overall vehicle power steering coordination per unit time; further, it can be seen that:

[0010] Furthermore, it can be seen that:

[0011] ;

[0012] It can be known that:

[0013] ,

[0014] Furthermore, it can be seen that: .

[0015] In the above technical solution, the specific process of calculating the absolute percentage of the total change in the relative difference of instantaneous assistance to each steering wheel is as follows: Calculation of the absolute percentage of the total increase in the relative difference of instantaneous assistance to each steering wheel: The absolute percentage of the total increase in the relative difference of instantaneous assistance to each steering wheel is equal to the absolute value of the relative difference of instantaneous assistance to each steering wheel divided by the total increase in assistance force of the entire vehicle; Calculation of the absolute percentage of the total decrease in the relative difference of instantaneous assistance to each steering wheel: The absolute percentage of the total decrease in the relative difference of instantaneous assistance to each steering wheel is equal to the absolute value of the relative difference of instantaneous assistance to each steering wheel divided by the total decrease in assistance force of the entire vehicle; The calculation formula is as follows: ,in: ——No. The absolute percentage of the increase in the relative difference of instantaneous power assist of each steering wheel; ——No. The absolute percentage of the total decrease in the relative difference of instantaneous power assist for each steering wheel; the specific process of calculating the change multiple of the maximum permissible change in power assist for each steering wheel per unit time is as follows: Calculation of the increase multiple of the maximum permissible increase in power assist for each steering wheel per unit time: The increase multiple of the maximum permissible increase in power assist for each steering wheel per unit time is equal to the maximum permissible increase in power assist for that steering wheel per unit time divided by the maximum increase in power assist for the entire vehicle per unit time; Calculation of the decrease multiple of the maximum permissible decrease in power assist for each steering wheel per unit time: The decrease multiple of the maximum permissible decrease in power assist for each steering wheel per unit time is equal to the maximum permissible decrease in power assist for that steering wheel per unit time divided by the maximum decrease in power assist for the entire vehicle per unit time; the calculation formula is: ,in: ——No. The multiple by which the maximum permissible increase in assist power per unit time is increased for each steering wheel; ——No. The factor by which the maximum permissible decrease in the power assist of each steering wheel per unit time is reduced further reveals that:

[0016] Furthermore, it can be seen that: .

[0017] In the above technical solution, the specific process of calculating the scaling factor of the absolute percentage of the total change in the relative difference of instantaneous assist of each steering wheel is as follows: Calculation of the scaling factor of the absolute percentage of the increase in the relative difference of instantaneous assist of each steering wheel: The scaling factor of the absolute percentage of the increase in the relative difference of instantaneous assist of each steering wheel is equal to the absolute percentage of the increase in the relative difference of instantaneous assist of each steering wheel divided by the increase factor of the maximum allowable increase in assist per unit time for that steering wheel; Calculation of the scaling factor of the absolute percentage of the decrease in the relative difference of instantaneous assist of each steering wheel: The scaling factor of the absolute percentage of the decrease in the relative difference of instantaneous assist of each steering wheel is equal to the absolute percentage of the decrease in the relative difference of instantaneous assist of each steering wheel divided by the decrease factor of the maximum allowable decrease in assist per unit time for that steering wheel; The calculation formula is: in: ——No. The scaling factor representing the absolute percentage increase in the relative difference of instantaneous assist to each steering wheel; ——No. The scaling factor is the absolute percentage of the decrease in the relative difference of the instantaneous assist of each steering wheel.

[0018] In the above technical solution, the specific process of calculating the maximum value of the scaling factor of the absolute percentage of the total change in the relative difference of instantaneous assist of each steering wheel is as follows: Calculation of the maximum value of the scaling factor of the absolute percentage of the increase in the relative difference of instantaneous assist: Calculate the maximum value of the scaling factor of the absolute percentage of the increase in the relative difference of instantaneous assist of each steering wheel; Calculation of the maximum value of the scaling factor of the absolute percentage of the decrease in the relative difference of instantaneous assist: Calculate the maximum value of the scaling factor of the absolute percentage of the decrease in the relative difference of instantaneous assist of each steering wheel; The calculation formula is: in: —The maximum value of the scaling factor representing the absolute percentage of the increase in the relative difference of the instantaneous assist of the steering wheels; —The maximum value of the scaling factor representing the absolute percentage of the decrease in the relative difference of instantaneous steering wheel assist can be further used to determine: .

[0019] In the above technical solution, the specific process of calculating the instantaneous assist change tracking coefficient of each steering wheel is as follows: Instantaneous assist increase tracking coefficient of each steering wheel: The instantaneous assist increase tracking coefficient of each steering wheel is equal to the maximum value of the scaling factor of the absolute percentage increase in the relative difference of the instantaneous assist of that steering wheel divided by the absolute percentage increase in the relative difference of the instantaneous assist of that steering wheel; Instantaneous assist decrease tracking coefficient of each steering wheel: The instantaneous assist decrease tracking coefficient of each steering wheel is equal to the maximum value of the scaling factor of the absolute percentage decrease in the relative difference of the instantaneous assist of that steering wheel divided by the absolute percentage decrease in the relative difference of the instantaneous assist of that steering wheel; its calculation formula is: in: ——No. Instantaneous assist to each steering wheel increases the tracking coefficient; ——No. The instantaneous assist of each steering wheel decreases the tracking coefficient.

[0020] In the above technical solution, the specific process of calculating the instantaneous assist change tracking amount of each steering wheel is as follows: Instantaneous assist increase tracking amount of each steering wheel: The instantaneous assist increase tracking amount of each steering wheel is equal to the instantaneous assist increase tracking coefficient of that steering wheel multiplied by the maximum value of the coordinated increase of the overall vehicle assist per unit time; Instantaneous assist decrease tracking amount of each steering wheel: The instantaneous assist decrease tracking amount of each steering wheel is equal to the instantaneous assist decrease tracking coefficient of that steering wheel multiplied by the maximum value of the coordinated decrease of the overall vehicle assist per unit time; The calculation formula is: in: ——No. Instantaneous power assist to each steering wheel increases tracking accuracy; ——No. The instantaneous assist change tracking amount of each steering wheel; further, based on the steps of calculating the instantaneous assist change tracking coefficient of each steering wheel, it can be known that: Further, based on the step of calculating the maximum value of the scaling factor of the absolute proportion of the total change in the relative difference of the instantaneous assist of each steering wheel, it can be known that: Further, based on the scaling factor used to calculate the absolute proportion of the total change in the relative difference of instantaneous assist to each steering wheel, it can be concluded that: Further analysis based on the steps of calculating the maximum permissible change factor of the power assist for each steering wheel per unit time reveals that: Therefore, it can be concluded that: since the instantaneous increase in steering assist of each steering wheel is less than or equal to the maximum permissible increase in steering assist per unit time, and the instantaneous decrease in steering assist of each steering wheel is less than or equal to the maximum permissible decrease in steering assist per unit time, the steering assist of each steering wheel is prevented from exceeding the range of capability change per unit time, thereby avoiding the problems of steering structure damage and reduced service life.

[0021] In the above technical solution, the specific process of calculating the instantaneous target assist of each steering wheel at the current moment based on the instantaneous assist change tracking amount of each steering wheel and the instantaneous target assist of each steering wheel at the previous moment is as follows: The instantaneous target assist of each steering wheel at the current moment is calculated based on the instantaneous assist increase tracking amount, the instantaneous assist decrease tracking amount, and the instantaneous target assist of each steering wheel at the previous moment; the calculation formula is: in: ——No. The instantaneous target assist of each steering wheel at the current moment. —Update iteration time; Update the instantaneous target assist of each steering wheel at the previous moment: Update the instantaneous target assist of each steering wheel at the previous moment as follows: Each steering wheel needs to perform target assistance: After multiple iterations, the instantaneous target assistance of each steering wheel at the current moment equals the target assistance required for each steering wheel; Tracking time required: The instantaneous target assistance of each steering wheel at the current moment equals the tracking time required for each steering wheel to perform target assistance. in: ——No. The instantaneous target assist for each steering wheel increases to the tracking time required for it to perform the target assist at the current moment; ——No. The instantaneous target assist of each steering wheel decreases to the point where it needs to perform the target assist; combined with the steps of calculating the instantaneous assist change tracking amount of each steering wheel, it can be further concluded that: Further analysis of the steps involved in calculating the instantaneous assist change tracking coefficient for each steering wheel reveals that: This can be further simplified to: By combining the steps of calculating the absolute percentage of the total change in the relative difference of instantaneous assist to each steering wheel, we can further conclude that: This can be further simplified to:

[0022] Combined with the formula in the step of calculating the maximum value of the coordinated change of the whole vehicle's power assist per unit time Furthermore, it can be seen that: Therefore, it can be seen that the instantaneous target assistance of each steering wheel at the current moment is equal to the tracking time required for that steering wheel to execute the target assistance, thus avoiding the problem that the instantaneous target assistance of each steering vehicle increases and decreases at different rates.

[0023] The present invention also provides a multi-wheel independent steering assist tracking control device, which has a computer program that can execute a multi-wheel independent steering assist tracking control method.

[0024] The multi-wheel independent steering assist tracking control method and device of the present invention have the following beneficial effects:

[0025] 1. The tracking time required for each steering wheel to increase its instantaneous target assist to the level required for that steering wheel to receive the target assist is equal at all times; the tracking time required for each steering wheel to decrease its instantaneous target assist to the level required for that steering wheel to receive the target assist is also equal at all times, and the tracking time required for each steering wheel to increase its instantaneous target assist to the level required for that steering wheel to receive the target assist is also equal to the tracking time required for each steering wheel to decrease its instantaneous target assist to receive the target assist. In other words, the tracking time required for each steering wheel to receive its instantaneous target assist to receive the target assist is the same, avoiding the problem of inconsistent tracking rates for increases and decreases in instantaneous target assist across different steering vehicles.

[0026] 2. The instantaneous power assist increase tracking amount of each steering wheel; the instantaneous power assist decrease tracking amount of each steering wheel is less than or equal to the maximum allowable increase in power assist per unit time and the maximum allowable decrease in power assist per unit time of each wheel, respectively, to avoid the steering assist of each steering wheel exceeding the range of capacity change per unit time, thereby avoiding the problems of steering structure damage and reduced service life, and improving the durability and reliability of the system. Attached Figure Description

[0027] Figure 1 This is a schematic diagram illustrating the overall concept of the multi-round independent steering assist tracking control method of the present invention;

[0028] Figure 2 This is a schematic diagram of the overall process of the multi-round independent steering assist tracking control method of the present invention;

[0029] Figure 3This is a schematic diagram of the multi-wheel independent steering assist tracking control device of the present invention. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments, but these embodiments should not be construed as limiting the present invention.

[0031] See Figure 1 The present invention provides a multi-round independent steering assist tracking control method, the overall idea of ​​which is as follows:

[0032] Calculate the relative difference between the target assist of each steering wheel and the instantaneous target assist of that steering wheel at the previous moment; obtain the maximum value of the overall vehicle assist change per unit time; calculate the total assist change of the entire vehicle; calculate the maximum value of the coordinated assist change of the entire vehicle per unit time; calculate the absolute percentage of the total change in the relative difference of instantaneous assist of each steering wheel; calculate the multiple of the maximum allowable change in assist of each steering wheel per unit time; calculate the scaling factor of the absolute percentage of the total change in the relative difference of instantaneous assist of each steering wheel; calculate the maximum value of the scaling factor of the absolute percentage of the total change in the relative difference of instantaneous assist of each steering wheel; calculate the tracking coefficient of instantaneous assist change of each steering wheel; calculate the tracking amount of instantaneous assist change of each steering wheel; and calculate the instantaneous target assist of each steering wheel at the current moment based on the tracking amount of instantaneous assist change of each steering wheel and the instantaneous target assist of each steering wheel at the previous moment.

[0033] See Figure 2 The specific steps of the multi-wheel independent steering assist tracking control method of the present invention are as follows:

[0034] Step 1: Calculate the relative difference between the target assist required for each steering wheel and the instantaneous target assist at the previous moment for that steering wheel. The calculation formula is as follows:

[0035]

[0036] in: ——No. The target assistance to be performed by each steering wheel; ——No. The instantaneous target assist of each steering wheel at a given moment; ——No. The relative difference in instantaneous assist to each steering wheel. —Steering wheel number, , This represents the total number of steering wheels.

[0037] Furthermore, it can be seen that: if the first Each steering wheel needs to perform target assistance. Greater than the The instantaneous target assist of each steering wheel at a given moment Then the first The relative difference in instantaneous assist of each steering wheel A value greater than zero indicates that the instantaneous target assistance should increase; if the first... Each steering wheel needs to perform target assistance. equal to the The instantaneous target assist of each steering wheel at a given moment Then the first The relative difference in instantaneous assist of each steering wheel Equal to zero indicates that the instantaneous target assistance remains unchanged; if the first... Each steering wheel needs to perform target assistance. Less than the The instantaneous target assist of each steering wheel at a given moment Then the first The relative difference in instantaneous assist of each steering wheel A value less than zero indicates that the instantaneous target assistance should decrease.

[0038] Step 2: Obtain the maximum increase and the maximum decrease of the vehicle's power assist per unit time. The specific process is as follows:

[0039] The calculation principle for the maximum change in vehicle power assist per unit time is as follows: The maximum increase in vehicle power assist per unit time is equal to the minimum allowable increase in power assist at all steering wheels per unit time for the instantaneous target power assist; the maximum decrease in vehicle power assist per unit time is equal to the minimum allowable decrease in power assist at all steering wheels per unit time for the instantaneous target power assist.

[0040] The calculation formula is as follows:

[0041]

[0042] in: —The maximum increase in vehicle assist per unit time; —The maximum decrease in the overall vehicle steering assist within a unit of time; ——No. The maximum permissible increase in power assist per unit time for each steering wheel; ——No. The maximum permissible decrease in the power assist of each steering wheel per unit time;

[0043] The maximum increase and the maximum decrease in vehicle power assist per unit time must satisfy the following characteristics: the maximum increase in vehicle power assist per unit time is not greater than the maximum permissible increase in power assist for each steering wheel per unit time; and the maximum decrease in vehicle power assist per unit time is not greater than the maximum permissible decrease in power assist for each steering wheel per unit time.

[0044] The calculation formula is as follows:

[0045]

[0046] Among them, the maximum permissible increase in power assist per unit time for each steering wheel It represents the maximum allowable increase or decrease in the assist force of each steering wheel per unit time. It represents the maximum allowable change of the steering wheel's mechanical structure per unit time. Exceeding the maximum allowable change of the steering wheel may lead to damage to the steering mechanical structure and a reduced service life. This set of parameters is determined by the characteristics of the steering mechanism.

[0047] Step 3: The specific process for calculating the increase and decrease in total vehicle power steering is as follows:

[0048] Calculation of total vehicle assist force: The total vehicle assist force is equal to the sum of the relative differences in the instantaneous assist force of all steering wheels that should be increased by the instantaneous target assist force;

[0049] Calculation of the decrease in total power assist of the vehicle: The decrease in total power assist of the vehicle is equal to the sum of the absolute values ​​of the relative differences of the instantaneous power assist of all steering wheels that should decrease in instantaneous target power assist;

[0050] The calculation formula is as follows:

[0051]

[0052] Step 4: Calculate the maximum increase and the maximum decrease of the vehicle's power steering coordination per unit time. The specific process for this step is as follows:

[0053] The maximum increase in vehicle power assist coordination and the maximum decrease in vehicle power assist coordination within a unit of time satisfy the following conditions: the maximum increase in vehicle power assist coordination within a unit of time is less than or equal to the corresponding maximum increase in vehicle power assist within a unit of time, and the maximum decrease in vehicle power assist coordination within a unit of time is less than or equal to the corresponding maximum decrease in vehicle power assist within a unit of time; and the ratio of the maximum increase in vehicle power assist coordination to the maximum decrease in vehicle power assist within a unit of time is equal to the ratio of the total increase in vehicle power assist to the total decrease in vehicle power assist.

[0054] The calculation formula is as follows:

[0055]

[0056] in: —The maximum increase in vehicle power assist coordination per unit time; —The maximum decrease in the overall vehicle power steering coordination within a unit of time;

[0057] Furthermore, it can be seen that:

[0058]

[0059] Furthermore, it can be seen that:

[0060]

[0061] It can be known that:

[0062]

[0063] Furthermore, it can also be known that: .

[0064] Step 5: Calculate the absolute percentage of the total increase in the relative difference of instantaneous power assist for each steering wheel and the absolute percentage of the total decrease in the relative difference of instantaneous power assist for each steering wheel. The specific process for this step is as follows:

[0065] The absolute percentage of the total increase in the relative difference of instantaneous power assist for each steering wheel is calculated as follows: The absolute percentage of the total increase in the relative difference of instantaneous power assist for each steering wheel is equal to the absolute value of the relative difference of instantaneous power assist for each steering wheel divided by the total increase in power assist for the entire vehicle.

[0066] The absolute percentage of the total decrease in the relative difference of instantaneous assist of each steering wheel is calculated as follows: The absolute percentage of the total decrease in the relative difference of instantaneous assist of each steering wheel is equal to the absolute value of the relative difference of instantaneous assist of each steering wheel divided by the total decrease in assist of the whole vehicle.

[0067] The calculation formula is as follows:

[0068]

[0069] in: ——No. The absolute percentage of the increase in the relative difference of instantaneous power assist of each steering wheel; ——No. The absolute percentage of the total decrease in the relative difference of instantaneous assist to each steering wheel.

[0070] Step 6: Calculate the increase factor of the maximum permissible increase in power assist per unit time for each steering wheel and the decrease factor of the maximum permissible decrease in power assist per unit time for each steering wheel. The specific process for this step is as follows:

[0071] Calculation of the increase factor of the maximum permissible increase in power assist of each steering wheel per unit time: The increase factor of the maximum permissible increase in power assist of each steering wheel per unit time is equal to the maximum increase in power assist of the entire vehicle per unit time.

[0072] Calculation of the reduction factor of the maximum permissible decrease in power assist of each steering wheel per unit time: The reduction factor of the maximum permissible decrease in power assist of each steering wheel per unit time is equal to the maximum permissible decrease in power assist of the steering wheel per unit time divided by the maximum decrease in power assist of the whole vehicle per unit time.

[0073] The calculation formula is as follows:

[0074]

[0075] in: ——No. The multiple by which the maximum permissible increase in assist power per unit time is increased for each steering wheel; ——No. The factor by which the maximum permissible decrease in assist power per unit time is reduced for each steering wheel.

[0076] Furthermore, it can be seen that:

[0077]

[0078] Furthermore, it can be seen that:

[0079] .

[0080] Step 7: The specific process for calculating the scaling factor of the absolute percentage increase in the relative difference of instantaneous assist to each steering wheel and the scaling factor of the absolute percentage decrease in the relative difference of instantaneous assist to each steering wheel is as follows:

[0081] Calculation of scaling factor for the absolute percentage increase of the relative difference in instantaneous assist of each steering wheel: The scaling factor for the absolute percentage increase of the relative difference in instantaneous assist of each steering wheel is equal to the absolute percentage increase of the relative difference in instantaneous assist of each steering wheel divided by the increase factor of the maximum allowable increase in assist per unit time of that steering wheel.

[0082] The scaling factor for the absolute percentage of the total decrease in the relative difference of the instantaneous assist of each steering wheel is calculated as follows: The scaling factor for the absolute percentage of the total decrease in the relative difference of the instantaneous assist of each steering wheel is equal to the absolute percentage of the total decrease in the relative difference of the instantaneous assist of each steering wheel divided by the factor by which the maximum allowable decrease in assist of that steering wheel per unit time is reduced.

[0083]

[0084] in: ——No. The scaling factor is the absolute percentage of the increase in the relative difference of the instantaneous assist of each steering wheel. ——No. The scaling factor is the absolute percentage of the decrease in the relative difference of the instantaneous assist of each steering wheel.

[0085] Step 8: The specific process for calculating the maximum value of the scaling factor for the absolute percentage increase of the relative difference in instantaneous assist of each steering wheel and the maximum value of the scaling factor for the absolute percentage decrease of the relative difference in instantaneous assist of each steering wheel is as follows:

[0086] Calculation of the maximum scaling factor for the absolute percentage increase in the relative difference of instantaneous assist: Calculate the maximum scaling factor for the absolute percentage increase in the relative difference of instantaneous assist for each steering wheel.

[0087] Calculation of the maximum scaling factor of the absolute percentage of the decrease in the relative difference of instantaneous assist: the maximum scaling factor of the absolute percentage of the decrease in the relative difference of instantaneous assist for each steering wheel.

[0088] The calculation formula is as follows:

[0089]

[0090] in: —The maximum value of the scaling factor representing the absolute percentage of the increase in the relative difference of the instantaneous assist of the steering wheels; —The maximum value of the scaling factor representing the absolute percentage of the decrease in the relative difference of instantaneous steering wheel assist.

[0091] Furthermore, it can be seen that:

[0092] .

[0093] Step 9: Calculate the tracking coefficient for the increase in instantaneous assist for each steering wheel based on the maximum value of the scaling factor for the absolute percentage increase in the relative difference of instantaneous assist between the steering wheels and the absolute percentage increase in the relative difference of instantaneous assist between each steering wheel. The specific process for calculating the tracking coefficient for the decrease in instantaneous assist for each steering wheel is as follows:

[0094] The tracking coefficient for the instantaneous assist increase of each steering wheel is equal to the maximum value of the scaling factor of the absolute percentage increase of the relative difference of the instantaneous assist of that steering wheel divided by the absolute percentage increase of the relative difference of the instantaneous assist of that steering wheel.

[0095] Tracking coefficient for instantaneous assist reduction of each steering wheel: The tracking coefficient for instantaneous assist reduction of each steering wheel is equal to the maximum value of the scaling factor of the absolute percentage of the total decrease in the relative difference of the instantaneous assist of that steering wheel divided by the absolute percentage of the total decrease in the relative difference of the instantaneous assist of that steering wheel.

[0096] The calculation formula is as follows:

[0097]

[0098] in: ——No. Instantaneous assist to each steering wheel increases the tracking coefficient; ——No. The instantaneous assist of each steering wheel decreases the tracking coefficient.

[0099] Step 10: Calculate the instantaneous assist increase tracking amount of each steering wheel based on the instantaneous assist increase tracking coefficient of each steering wheel and the maximum value of the coordinated increase of the whole vehicle assist per unit time; and calculate the instantaneous assist decrease tracking amount of each steering wheel based on the instantaneous assist decrease tracking coefficient of each steering wheel and the maximum value of the coordinated decrease of the whole vehicle assist per unit time.

[0100] The instantaneous increase in steering wheel assist tracking amount is equal to the instantaneous increase in steering wheel assist tracking coefficient multiplied by the maximum value of the overall vehicle assist coordinated increase per unit time;

[0101] The instantaneous decrease in power assist tracking amount of each steering wheel is equal to the instantaneous decrease in power assist tracking coefficient of that steering wheel multiplied by the maximum value of the overall vehicle power assist decrease per unit time.

[0102] The calculation formula is as follows:

[0103]

[0104] in: ——No. Instantaneous power assist to each steering wheel increases tracking accuracy; ——No. The instantaneous power assist of each steering wheel decreases in tracking amount;

[0105] Further information from step 9 indicates that:

[0106]

[0107] Further information from step 8 indicates that:

[0108]

[0109] Further information from step 7 indicates that:

[0110]

[0111] Further information from step 6 indicates that:

[0112]

[0113] Therefore, it can be concluded that: since the instantaneous increase in steering assist of each steering wheel is less than or equal to the maximum permissible increase in steering assist per unit time, and the instantaneous decrease in steering assist of each steering wheel is less than or equal to the maximum permissible decrease in steering assist per unit time, the steering assist of each steering wheel is prevented from exceeding the range of capability change per unit time, thereby avoiding the problems of steering structure damage and reduced service life.

[0114] Step 11: The specific process of calculating the instantaneous target assist of each steering wheel at the current moment based on the instantaneous assist change tracking amount of each steering wheel and the instantaneous target assist of each steering wheel at the previous moment is as follows:

[0115] The instantaneous target assist of each steering wheel at the current moment is calculated based on the tracking amount of the instantaneous assist increase of each steering wheel, the tracking amount of the instantaneous assist decrease of each steering wheel, and the instantaneous target assist of each steering wheel at the previous moment.

[0116] The calculation formula is as follows:

[0117]

[0118] in: ——No. The instantaneous target assist for each steering wheel at the current moment. —Update and iteration time.

[0119] Update the instantaneous target assist for each steering wheel at the previous moment: Update the instantaneous target assist for each steering wheel at the previous moment as follows: ;

[0120] Each steering wheel needs to perform target assistance: After multiple iterations and updates, the instantaneous target assistance of each steering wheel at the current moment is equal to the target assistance that the steering wheel needs to perform;

[0121] Tracking time required: The instantaneous target assist of each steering wheel at the current moment is equal to the tracking time required for it to perform the target assist.

[0122]

[0123] in: ——No. The instantaneous target assist for each steering wheel increases to the tracking time required for it to perform the target assist at the current moment; ——No. The instantaneous target assist of each steering wheel decreases to the tracking time required for it to perform target assist at the current moment;

[0124] Further, based on step 10, we can conclude that:

[0125]

[0126] Further, based on step 9, we can conclude that:

[0127]

[0128] This can be further simplified to:

[0129]

[0130] Further, based on step 5, we can conclude that:

[0131]

[0132] This can be further simplified to:

[0133]

[0134] Combined with the formula in step 4 Furthermore, it can be seen that:

[0135]

[0136] Therefore, it can be concluded that: the tracking time required for each steering wheel to increase its instantaneous target assist to the point where it can perform the target assist is equal; the tracking time required for each steering wheel to decrease its instantaneous target assist to the point where it can perform the target assist is also equal, and the tracking time required for each steering wheel to increase its instantaneous target assist to the point where it can perform the target assist is equal to the tracking time required for each steering wheel to perform the target assist. Thus, the fact that the instantaneous target assist of each steering wheel at the current moment equals the same tracking time for it to perform the target assist avoids the problem of inconsistent rates of increase and decrease in instantaneous target assist across different steering vehicles.

[0137] See Figure 3 The present invention provides a multi-wheel independent steering assist tracking control device, comprising the following parts:

[0138] Relative Difference Module: Calculates the relative difference between the target assist of each steering wheel and the instantaneous target assist of that steering wheel at the previous moment;

[0139] Maximum value of vehicle power steering change module: Gets the maximum value of the change in vehicle power steering within a unit of time;

[0140] Total Assist Change Module: Calculates the total assist change of the entire vehicle;

[0141] Maximum value module for coordinated change of vehicle power steering: Calculates the maximum value of coordinated change of vehicle power steering per unit time;

[0142] The module for absolute percentage of total change: calculates the absolute percentage of the total change in the relative difference of instantaneous assist to each steering wheel;

[0143] Change factor module: Calculates the change factor of the maximum permissible change in assist power per unit time for each steering wheel;

[0144] Scaling factor module: Calculates the scaling factor as the absolute percentage of the total change in the relative difference of the instantaneous assist of each steering wheel;

[0145] The maximum scaling factor module calculates the maximum scaling factor as the absolute percentage of the total change in the relative difference of the instantaneous assist of each steering wheel.

[0146] Tracking coefficient module: Calculates the tracking coefficient for the instantaneous power assist change of each steering wheel;

[0147] Tracking Module: Calculates the instantaneous power assist change tracking amount for each steering wheel;

[0148] Instantaneous target assist module: The instantaneous target assist of each steering wheel is calculated based on the tracking amount of the instantaneous assist change of each steering wheel and the instantaneous target assist of each steering wheel at the previous moment.

[0149] The technical advantages of the multi-wheel independent steering assist tracking control method and device of the present invention are as follows:

[0150] 1. The tracking time required for each steering wheel to increase its instantaneous target assist to the level required for that steering wheel to receive the target assist is equal at all times; the tracking time required for each steering wheel to decrease its instantaneous target assist to the level required for that steering wheel to receive the target assist is also equal at all times, and the tracking time required for each steering wheel to increase its instantaneous target assist to the level required for that steering wheel to receive the target assist is also equal to the tracking time required for each steering wheel to decrease its instantaneous target assist to receive the target assist. In other words, the tracking time required for each steering wheel to receive its instantaneous target assist to receive the target assist is the same, avoiding the problem of inconsistent tracking rates for increases and decreases in instantaneous target assist across different steering vehicles.

[0151] 2. The instantaneous power assist increase tracking amount of each steering wheel; the instantaneous power assist decrease tracking amount of each steering wheel is less than or equal to its maximum allowable increase in power assist per unit time and its maximum allowable decrease in power assist per unit time, respectively. This avoids the steering assist of each steering wheel from exceeding the range of capacity change per unit time, thereby avoiding problems such as steering structure damage and reduced service life, and improving the durability and reliability of the system.

[0152] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

[0153] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

Claims

1. A multi-wheel independent steering assist tracking control method, characterized in that: The specific process of this method is as follows: Calculate the relative difference between the target assist of each steering wheel and the instantaneous target assist of that steering wheel at the previous moment, obtain the maximum value of the change in vehicle assist per unit time, calculate the total change in vehicle assist, calculate the maximum value of the coordinated change in vehicle assist per unit time, calculate the absolute percentage of the total change in the relative difference of instantaneous assist of each steering wheel, calculate the change multiple of the maximum allowable change in assist of each steering wheel per unit time, calculate the scaling factor of the absolute percentage of the total change in the relative difference of instantaneous assist of each steering wheel, calculate the maximum value of the scaling factor of the absolute percentage of the total change in the relative difference of instantaneous assist of each steering wheel, calculate the tracking coefficient of instantaneous assist change of each steering wheel, calculate the tracking amount of instantaneous assist change of each steering wheel, and calculate the instantaneous target assist of each steering wheel at the current moment based on the tracking amount of instantaneous assist change of each steering wheel and the instantaneous target assist of each steering wheel at the previous moment. The specific process for calculating the relative difference between the target assist of each steering wheel and its instantaneous target assist at the previous moment is as follows: Calculate the relative difference between the target assist required for each steering wheel and the instantaneous target assist of that steering wheel at the previous moment: ， in: ——No. The target assistance to be performed by each steering wheel; ——No. The instantaneous target assist of each steering wheel at a given moment; ——No. The relative difference in instantaneous assist to each steering wheel. —Steering wheel number, , This refers to the total number of steering wheels; The specific process for obtaining the maximum value of the change in vehicle assist within a unit of time is as follows: The calculation principle for the maximum change in vehicle power assist per unit time is as follows: The maximum increase in vehicle power assist per unit time is equal to the minimum allowable increase in power assist for all steering wheels that should have the instantaneous target power assist per unit time; the maximum decrease in vehicle power assist per unit time is equal to the minimum allowable decrease in power assist for all steering wheels that should have the instantaneous target power assist per unit time. The calculation formula is as follows: ， in: —The maximum increase in vehicle assist per unit time; —The maximum decrease in the overall vehicle steering assist within a unit of time; ——No. The maximum permissible increase in power assist per unit time for each steering wheel; ——No. The maximum permissible decrease in the power assist of each steering wheel per unit time; The maximum increase in vehicle power assist per unit time and the maximum decrease in vehicle power assist per unit time satisfy the following: the maximum increase in vehicle power assist per unit time is not greater than the maximum permissible increase in power assist for each steering wheel per unit time, and the maximum decrease in vehicle power assist per unit time is not greater than the maximum permissible decrease in power assist for each steering wheel per unit time. The calculation formula is as follows: 。 2. The multi-wheel independent steering assist tracking control method according to claim 1, characterized in that: The steps for calculating the change in total vehicle power steering include calculating both the increase and decrease in total vehicle power steering, and the specific process is as follows: Calculation of total power assist increase for the whole vehicle: The total power assist increase for the whole vehicle is equal to the sum of the relative differences of the instantaneous power assist of all steering wheels that should be increased by the instantaneous target power assist; Calculation of the decrease in total power assist of the vehicle: The decrease in total power assist of the vehicle is equal to the sum of the absolute values ​​of the relative differences of the instantaneous power assist of all steering wheels that should decrease in instantaneous target power assist; The calculation formula is as follows: The specific process for calculating the maximum value of the vehicle's power assist coordination change per unit time is as follows: The maximum value of the change in vehicle power assist coordination per unit time satisfies the following: the maximum increase in vehicle power assist coordination per unit time is less than or equal to the maximum increase in vehicle power assist per unit time, and the maximum decrease in vehicle power assist coordination per unit time is less than or equal to the maximum decrease in vehicle power assist per unit time, and the ratio of the maximum increase in vehicle power assist coordination to the maximum decrease in vehicle power assist coordination per unit time is equal to the ratio of the total increase in vehicle power assist to the total decrease in vehicle power assist. The calculation formula is as follows: in: —The maximum increase in vehicle power assist coordination per unit time; —The maximum decrease in the overall vehicle power steering coordination within a unit of time; Furthermore, it can be seen that: ， Furthermore, it can be seen that: ； It can be known that: ， Furthermore, it can be seen that: .

3. The multi-wheel independent steering assist tracking control method according to claim 2, characterized in that: The specific process for calculating the absolute percentage of the total change in the relative difference of instantaneous assist to each steering wheel is as follows: The absolute percentage of the total increase in the relative difference of instantaneous power assist for each steering wheel is calculated as follows: The absolute percentage of the total increase in the relative difference of instantaneous power assist for each steering wheel is equal to the absolute value of the relative difference of instantaneous power assist for each steering wheel divided by the total increase in power assist for the entire vehicle. The absolute percentage of the total decrease in the relative difference of instantaneous assist of each steering wheel is calculated as follows: The absolute percentage of the total decrease in the relative difference of instantaneous assist of each steering wheel is equal to the absolute value of the relative difference of instantaneous assist of each steering wheel divided by the total decrease in assist of the whole vehicle. The calculation formula is as follows: ， in: ——No. The absolute percentage of the increase in the relative difference of instantaneous power assist of each steering wheel; ——No. The absolute percentage of the total decrease in the relative difference of instantaneous assist to each steering wheel; The specific process for calculating the multiple of the maximum permissible change in assist power per unit time for each steering wheel is as follows: Calculation of the increase factor of the maximum permissible increase in power assist of each steering wheel per unit time: The increase factor of the maximum permissible increase in power assist of each steering wheel per unit time is equal to the maximum permissible increase in power assist of that steering wheel per unit time divided by the maximum increase in power assist of the whole vehicle per unit time. Calculation of the reduction factor of the maximum permissible decrease in power assist of each steering wheel per unit time: The reduction factor of the maximum permissible decrease in power assist of each steering wheel per unit time is equal to the maximum permissible decrease in power assist of that steering wheel per unit time divided by the maximum decrease in power assist of the whole vehicle per unit time. The calculation formula is as follows: ， in: ——No. The multiple by which the maximum permissible increase in assist power per unit time is increased for each steering wheel; ——No. The factor by which the maximum permissible decrease in assist power per unit time is reduced for each steering wheel. Furthermore, it can be seen that: ， Furthermore, it can be seen that: 。 4. The multi-wheel independent steering assist tracking control method according to claim 3, characterized in that: The specific process for calculating the scaling factor of the absolute percentage of the total change in the relative difference of instantaneous assist of each steering wheel is as follows: Calculation of scaling factor for the absolute percentage increase of the relative difference in instantaneous assist of each steering wheel: The scaling factor for the absolute percentage increase of the relative difference in instantaneous assist of each steering wheel is equal to the absolute percentage increase of the relative difference in instantaneous assist of each steering wheel divided by the increase factor of the maximum allowable increase in assist per unit time of that steering wheel. The scaling factor for the absolute percentage of the total decrease in the relative difference of the instantaneous assist of each steering wheel is calculated as follows: The scaling factor for the absolute percentage of the total decrease in the relative difference of the instantaneous assist of each steering wheel is equal to the absolute percentage of the total decrease in the relative difference of the instantaneous assist of each steering wheel divided by the factor by which the maximum allowable decrease in assist of that steering wheel per unit time is reduced. The calculation formula is as follows: in: ——No. The scaling factor representing the absolute percentage increase in the relative difference of instantaneous assist to each steering wheel; ——No. The scaling factor is the absolute percentage of the decrease in the relative difference of the instantaneous assist of each steering wheel.

5. The multi-wheel independent steering assist tracking control method according to claim 4, characterized in that: The specific process for calculating the maximum value of the scaling factor for the absolute percentage of the total change in the relative difference of the instantaneous assist of each steering wheel is as follows: Calculation of the maximum scaling factor for the absolute percentage increase in the relative difference of instantaneous assist: Calculate the maximum scaling factor for the absolute percentage increase in the relative difference of instantaneous assist for each steering wheel. Calculation of the maximum scaling factor of the absolute percentage of the decrease in the relative difference of instantaneous assist: the maximum scaling factor of the absolute percentage of the decrease in the relative difference of instantaneous assist for each steering wheel. The calculation formula is as follows: in: —The maximum value of the scaling factor representing the absolute percentage of the increase in the relative difference of the instantaneous assist of the steering wheels; —The maximum value of the scaling factor representing the absolute percentage of the decrease in the relative difference of instantaneous steering wheel assist. Furthermore, it can be seen that: 。 6. The multi-wheel independent steering assist tracking control method according to claim 5, characterized in that: The specific process for calculating the instantaneous assist change tracking coefficient for each steering wheel is as follows: The tracking coefficient for the instantaneous assist increase of each steering wheel is equal to the maximum value of the scaling factor of the absolute percentage increase of the relative difference of the instantaneous assist of that steering wheel divided by the absolute percentage increase of the relative difference of the instantaneous assist of that steering wheel. Tracking coefficient for instantaneous assist reduction of each steering wheel: The tracking coefficient for instantaneous assist reduction of each steering wheel is equal to the maximum value of the scaling factor of the absolute percentage of the total decrease in the relative difference of the instantaneous assist of that steering wheel divided by the absolute percentage of the total decrease in the relative difference of the instantaneous assist of that steering wheel. The calculation formula is as follows: in: ——No. Instantaneous assist to each steering wheel increases the tracking coefficient; ——No. The instantaneous assist of each steering wheel decreases the tracking coefficient.

7. The multi-wheel independent steering assist tracking control method according to claim 6, characterized in that: The specific process for calculating the instantaneous power assist change tracking amount of each steering wheel is as follows: Instantaneous power assist increase tracking amount for each steering wheel: The instantaneous power assist increase tracking amount for each steering wheel is equal to the instantaneous power assist increase tracking coefficient of that steering wheel multiplied by the maximum value of the coordinated increase in the overall vehicle power assist per unit time; Instantaneous power assist reduction tracking amount for each steering wheel: The instantaneous power assist reduction tracking amount for each steering wheel is equal to the instantaneous power assist reduction tracking coefficient of that steering wheel multiplied by the maximum value of the overall vehicle power assist reduction per unit time. The calculation formula is as follows: in: ——No. Instantaneous power assist to each steering wheel increases tracking accuracy; ——No. The instantaneous power assist of each steering wheel decreases in tracking amount; Further analysis based on the calculation steps for the instantaneous assist change tracking coefficient of each steering wheel reveals that: Further, based on the step of calculating the maximum value of the scaling factor of the absolute proportion of the total change in the relative difference of the instantaneous assist of each steering wheel, it can be known that: Further, based on the scaling factor used to calculate the absolute proportion of the total change in the relative difference of instantaneous assist to each steering wheel, it can be concluded that: Further analysis based on the steps of calculating the maximum permissible change factor of the power assist for each steering wheel per unit time reveals that: Therefore, it can be concluded that: since the instantaneous increase in steering assist of each steering wheel is less than or equal to the maximum permissible increase in steering assist per unit time, and the instantaneous decrease in steering assist of each steering wheel is less than or equal to the maximum permissible decrease in steering assist per unit time, the steering assist of each steering wheel is prevented from exceeding the range of capability change per unit time, thereby avoiding the problems of steering structure damage and reduced service life.

8. The multi-wheel independent steering assist tracking control method according to claim 7, characterized in that: The specific process for calculating the instantaneous target assist of each steering wheel at the current moment based on the instantaneous assist change tracking amount of each steering wheel and the instantaneous target assist of each steering wheel at the previous moment is as follows: The instantaneous target assist of each steering wheel at the current moment is calculated based on the tracking amount of the instantaneous assist increase of each steering wheel, the tracking amount of the instantaneous assist decrease of each steering wheel, and the instantaneous target assist of each steering wheel at the previous moment. The calculation formula is as follows: in: ——No. The instantaneous target assist of each steering wheel at the current moment. —Update and iteration time; Update the instantaneous target assist for each steering wheel at the previous moment: Update the instantaneous target assist for each steering wheel at the previous moment as follows: ; Each steering wheel needs to perform target assistance: After multiple iterations and updates, the instantaneous target assistance of each steering wheel at the current moment is equal to the target assistance that each steering wheel needs to perform. Tracking time required: The instantaneous target assist of each steering wheel at the current moment is equal to the tracking time required for each steering wheel to perform the target assist. in: ——No. The instantaneous target assist for each steering wheel increases to the tracking time required for it to perform the target assist at the current moment; ——No. The instantaneous target assist of each steering wheel decreases to the tracking time required for it to perform target assist at the current moment; Further analysis of the steps involved in calculating the instantaneous power assist change tracking amount for each steering wheel reveals that: Further analysis of the steps involved in calculating the instantaneous assist change tracking coefficient for each steering wheel reveals that: This can be further simplified to: By combining the steps of calculating the absolute percentage of the total change in the relative difference of instantaneous assist to each steering wheel, we can further conclude that: This can be further simplified to: Combined with the formula in the step of calculating the maximum value of the coordinated change of the whole vehicle's power assist per unit time Furthermore, it can be seen that: Therefore, it can be seen that the instantaneous target assistance of each steering wheel at the current moment is equal to the tracking time required for that steering wheel to execute the target assistance, thus avoiding the problem that the instantaneous target assistance of each steering vehicle increases and decreases at different rates.

9. A multi-wheel independent steering assist tracking control device, comprising a computer program, characterized in that: The computer program is capable of executing the multi-wheel independent steering assist tracking control method as described in any one of claims 1 to 8.

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