A method for selecting proportional coefficients for variable angular transmission ratios

Abstract

The present invention relates to a method for selecting a proportional coefficient for a variable angular transmission ratio, comprising the following steps: S1, designing the variable angular transmission ratio in sections, defining 0-30 km / h as a low speed section, 30-70 km / h as a medium-low speed section, 70-120 km / h as a medium-high speed section, and greater than 120 km / h as a high speed section; S2, establishing quantitative evaluation criteria for steering sensitivity and handling stability; S3, obtaining an optimal proportional coefficient; and S4, establishing a quantitative relationship expression between vehicle speed u and the optimal proportional coefficient p through a fitting method. By designing proportional coefficients in different vehicle speed ranges to adjust the angular transmission ratio, the present invention can achieve a situation where steering sensitivity is prioritized at low and medium speeds, and handling stability is prioritized at medium and high speeds, thereby balancing ease of operation and safety for the driver.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile steer-by-wire technology, and more particularly to a method for selecting a proportional coefficient for a variable angular transmission ratio. Background Art

[0002] Variable angular transmission ratio is one of the key technologies for fully leveraging the performance advantages of steer-by-wire. Currently, the mainstream approach to designing the variable angular transmission ratio is to combine a constant yaw rate gain and a constant lateral acceleration gain. The core issue of this approach is determining the proportional coefficient between the two gains. However, in existing technologies, the determination of the proportional coefficient is primarily based on empirically fitting a curve that correlates the proportional coefficient with vehicle speed. There is no specific method for obtaining a mathematical equation for this relationship, resulting in considerable arbitrariness. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for selecting a proportional coefficient for a variable angular transmission ratio, which can select the proportional coefficient according to different vehicle speed ranges while taking into account the steering sensitivity and handling stability of the vehicle.

[0004] The technical solution adopted by the present invention to solve the technical problem is to construct a method for selecting a proportional coefficient for a variable angular transmission ratio, comprising the following steps:

[0005] S1. Design the variable angle transmission ratio in sections, defining 0-30 km / h as the low speed section, 30-70 km / h as the medium-low speed section, 70-120 km / h as the medium-high speed section, and greater than 120 km / h as the high speed section;

[0006] S2. Establish quantitative evaluation criteria for steering sensitivity and handling stability;

[0007] In the low and medium speed range, steering sensitivity is given priority. The yaw rate gain and yaw rate overshoot under steering wheel angle step input can both reflect the steering sensitivity of the vehicle. The quantitative evaluation standard J1 of steering sensitivity is obtained by weighting the yaw rate gain and yaw rate overshoot.

[0008] Prioritize handling stability in the medium and high speed range. Yaw rate, lateral acceleration, and sideslip angle values ​​can all reflect the vehicle's handling stability. A quantitative evaluation criterion for handling stability, J2, is derived by weighting these three factors.

[0009] S3, obtaining the optimal proportional coefficient;

[0010] In the low and medium speed range, the transient response of the vehicle under the steering wheel input is an important part of evaluating the steering sensitivity. Different proportional coefficients p and vehicle speeds u are selected to conduct steering wheel angle step tests, and the values ​​of J1 are compared. The proportional coefficient with the maximum J1 value at each vehicle speed is taken as the optimal proportional coefficient.

[0011] At medium and high speeds, the transient response of a vehicle under double lane change conditions is an important basis for evaluating handling stability. Double lane change tests were conducted using different proportional coefficients p and vehicle speeds u. The J2 values ​​were compared, and the optimal proportional coefficient was determined to be the one with the minimum J2 value at each vehicle speed.

[0012] S4. Establish a quantitative relationship expression between the vehicle speed u and the optimal proportional coefficient p through a fitting method.

[0013] According to the above scheme, in step S2, the method for establishing the quantitative evaluation standard J1 of steering sensitivity in the medium and low speed range is:

[0014] The steering sensitivity is evaluated by combining the yaw rate gain k and the yaw rate overshoot σ under the steering wheel step input. The expression is:

[0015]

[0016] Where a1 and a2 are the proportional coefficients of k and σ respectively.

[0017] According to the above scheme, in step S2, the method for establishing the quantitative evaluation standard J2 of handling stability in the medium and high speed range is:

[0018] The vehicle's yaw rate w r , lateral acceleration a y The control stability is evaluated by combining the center of mass side slip angle β and the control stability, and the expression is:

[0019]

[0020] Where k1, k2, and k3 are w r 、a y , the proportional coefficient of β.

[0021] According to the above scheme, step S3 includes the following steps:

[0022] S3.1. Obtain the optimal proportionality coefficient p at different vehicle speeds in the medium and low speed ranges; conduct steering wheel angle step tests at each selected vehicle speed, and obtain quantitative evaluation standard values ​​for the vehicle's steering sensitivity at different vehicle speeds corresponding to the different proportionality coefficients;

[0023] S3.2. Obtain the optimal proportionality coefficient p at different vehicle speeds in the medium and high speed range; conduct double lane change tests at the selected different speeds, and obtain quantitative evaluation standard values ​​for the vehicle's handling stability at different vehicle speeds corresponding to the different proportionality coefficients.

[0024] According to the above scheme, step S4 includes the following steps:

[0025] S4.1. Establish a relationship between the optimal proportional coefficient p and vehicle speed u in the medium and low speed range. By fitting the nine sets of data obtained in step S3.1, the optimal proportional coefficient p at each vehicle speed in the medium and low speed range is obtained:

[0026] p=f1(u) (3)

[0027] Where u is the vehicle speed, f1(u) is the multi-term function to be fitted;

[0028] S4.2. Establish a relationship between the optimal proportional coefficient p and vehicle speed u in the medium- and high-speed range. By fitting the 11 sets of data obtained in step S3.2, the optimal proportional coefficient p at each vehicle speed in the medium- and high-speed range is obtained:

[0029] p=f2(u) (4)

[0030] Where u is the vehicle speed, and f2(u) is the multi-term function to be fitted.

[0031] The method for selecting a proportional coefficient for a variable angular transmission ratio according to the present invention has the following beneficial effects:

[0032] The present invention adjusts the angular transmission ratio by designing a proportional coefficient in different vehicle speed ranges, thereby achieving steering sensitivity as the main focus at medium and low vehicle speeds and handling stability as the main focus at medium and high vehicle speeds, taking into account both the ease of operation and safety of the driver. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0034] Figure 1 The present invention is a flow chart of a method for selecting a proportional coefficient for a variable angular transmission ratio. DETAILED DESCRIPTION

[0035] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0036] like Figure 1 As shown, the method for selecting the proportional coefficient of the variable angular transmission ratio of the present invention includes the following steps:

[0037] S1, adopts segmented concept to design variable angle transmission ratio.

[0038] S2. Establish quantitative evaluation criteria for steering sensitivity and handling stability.

[0039] Steering sensitivity is given priority in the low and medium speed ranges. The yaw rate gain value and yaw rate overshoot value under the steering wheel angle step input can both reflect the steering sensitivity of the vehicle. Therefore, the quantitative evaluation standard J1 of steering sensitivity is obtained by weighting the two parameter values.

[0040] In the medium and high speed range, handling stability is given priority. The yaw rate, lateral acceleration and sideslip angle value of the center of mass can all reflect the handling stability of the vehicle. Therefore, the three parameter values ​​are weighted and combined to obtain the quantitative evaluation standard J2 for handling stability.

[0041] S3, obtain the optimal proportional coefficient.

[0042] In the medium and low speed range, the transient response of the vehicle under steering wheel input is an important part of evaluating steering sensitivity. Therefore, different proportional coefficients p and vehicle speeds u are selected to carry out steering wheel angle step tests, and the values ​​of J1 are compared. The proportional coefficient with the maximum J1 value at each vehicle speed is taken as the optimal proportional coefficient.

[0043] In the medium and high speed range, the transient response of a vehicle under double lane change conditions is an important basis for evaluating handling stability. Therefore, different proportional coefficients p and vehicle speeds u are selected for double lane change tests, and the values ​​of J2 are compared. The proportional coefficient with the minimum J2 value at each vehicle speed is taken as the optimal proportional coefficient.

[0044] S4, establishing a quantitative relationship expression between the vehicle speed u and the optimal proportional coefficient p through a fitting method.

[0045] Preferably, step S1 specifically includes the following steps:

[0046] The variable angle transmission ratio is designed using a segmented approach, where 0-30km / h is defined as a low-speed segment, 30-70km / h as a medium-low-speed segment, 70-120km / h as a medium-high-speed segment, and greater than 120km / h as a high-speed segment.

[0047] Preferably, step S2 specifically includes the following steps:

[0048] S2.1. Establish quantitative evaluation criteria for steering sensitivity in the low and medium speed ranges:

[0049] The steering sensitivity is evaluated by combining the yaw rate gain k and the yaw rate overshoot σ under the steering wheel step input. The expression is:

[0050]

[0051] Where a1 and a2 are the proportional coefficients of k and σ respectively, and their values ​​can be adjusted. Here they are both taken as 0.5.

[0052] S2.2, establish quantitative evaluation criteria for handling stability in the medium and high speed range:

[0053] The vehicle's yaw rate w r , lateral acceleration a y The control stability is evaluated by combining the center of mass side slip angle β and the control stability, and the expression is:

[0054]

[0055] Where k1, k2, and k3 are w r 、a y The proportional coefficients of , β can be adjusted, and are both taken as 1 / 3 here.

[0056] Preferably, step S3 specifically includes the following steps:

[0057] S3.1, obtain the optimal proportional coefficient p at different vehicle speeds in the medium and low speed range:

[0058] The present invention starts from a vehicle speed of 30 km / h and selects a simulated vehicle speed every 5 km / h, including 9 groups of vehicle speeds, including 30 km / h, 35 km / h...70 km / h;

[0059] The present invention starts from the proportional coefficient p=1, and selects a proportional coefficient every 0.05, including 9 groups of coefficients including 1, 0.95...0.65, and 0.6;

[0060] According to the selected different vehicle speeds, the steering wheel angle step test is carried out respectively, and the quantitative evaluation standard values ​​of the vehicle steering sensitivity at different vehicle speeds corresponding to different proportional coefficients are obtained, as shown in Table 1. ij Represents the quantitative evaluation standard value of the steering sensitivity corresponding to the i-th group of vehicle speed and the j-th group of proportional coefficient, where i, j = 1, 2...9:

[0061] Table 1 Quantitative evaluation standard values ​​of vehicle steering sensitivity at different speeds corresponding to different proportional coefficients

[0062]

[0063]

[0064] The proportional coefficients corresponding to the maximum steering sensitivity quantitative evaluation standard value are obtained from the nine sets of proportional coefficients at each vehicle speed: (30, b1), (35, b2)…(65, b8), (70, b9), where b1 to b9 are the optimal proportional coefficients corresponding to the nine sets of vehicle speeds.

[0065] S3.2, obtain the optimal proportional coefficient p for different vehicle speeds in the medium and high speed range:

[0066] The present invention starts from a vehicle speed of 70 km / h and selects a simulation speed every 5 km / h, including 11 groups of vehicle speeds, including 70 km / h, 75 km / h...120 km / h;

[0067] The present invention starts from the proportional coefficient p=1, and selects a proportional coefficient every 0.05, including 9 groups of proportional coefficients p, including 1, 0.95...0.65, and 0.6;

[0068] The double lane change test was carried out according to the selected different vehicle speeds, and the quantitative evaluation standard values ​​of the vehicle's handling stability at different vehicle speeds corresponding to different proportional coefficients were obtained, as shown in Table 2. ij Represents the quantitative evaluation standard value of the handling stability corresponding to the i-th group of vehicle speeds and the j-th group of proportional coefficients, where i = 1, 2...11 and j = 1, 2...9:

[0069] Table 2 Quantitative evaluation standard values ​​of vehicle handling stability at different speeds corresponding to different proportional coefficients

[0070]

[0071] The proportional coefficients corresponding to the minimum standard value of quantitative evaluation of handling stability are obtained from the 9 groups of proportional coefficients at each vehicle speed: (70, e1), (75, e2)…(115, e 10 )、(120,e 11 ), where e1 to e 11 is the optimal proportional coefficient corresponding to 11 groups of vehicle speeds;

[0072] Preferably, step S4 specifically includes the following steps:

[0073] S4.1. Establish the relationship between the optimal proportional coefficient p and vehicle speed u in the medium and low speed ranges:

[0074] By fitting the 9 sets of data obtained in step S3.1, the optimal proportional coefficient p at each vehicle speed in the medium and low speed range is obtained:

[0075] p=f1(u) (3)

[0076] Where u is the vehicle speed and f1(u) is the multi-term function to be fitted.

[0077] S4.2. Establish the relationship between the optimal proportional coefficient p and vehicle speed u in the medium and high speed range:

[0078] By fitting the 11 sets of data obtained in step S3.2, the optimal proportional coefficient p for each vehicle speed in the medium and high speed range is obtained:

[0079] p=f2(u) (4)

[0080] Where u is the vehicle speed, and f2(u) is the multi-term function to be fitted.

[0081] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A method for selecting a proportional coefficient for a variable angular transmission ratio, characterized in that: The steps include: S1, segmented design of variable angle transmission ratio, segmented into low speed range, medium-low speed range, medium-high speed range and high speed range; S2. Establish quantitative evaluation criteria for steering sensitivity and handling stability; In the low and medium speed range, steering sensitivity is given priority. The yaw rate gain and yaw rate overshoot under the steering wheel angle step input can both reflect the steering sensitivity of the vehicle. The quantitative evaluation standard J1 of steering sensitivity is obtained by weighting the yaw rate gain and yaw rate overshoot. Prioritize handling stability in the medium and high speed range. Yaw rate, lateral acceleration, and sideslip angle values ​​can all reflect the vehicle's handling stability. A quantitative evaluation criterion for handling stability, J2, is derived by weighting these three factors. S3, obtaining the optimal proportional coefficient; In the low and medium speed range, the transient response of the vehicle steering wheel input is an important part of evaluating steering sensitivity. Different proportional coefficients p and vehicle speeds u are selected to conduct steering wheel angle step tests, and the values ​​of J1 are compared. The proportional coefficient with the maximum J1 value at each vehicle speed is taken as the optimal proportional coefficient. In the medium and high speed range, the transient response of the vehicle under double lane change conditions is an important basis for evaluating handling stability. Double lane change tests were conducted with different proportional coefficients p and vehicle speeds u. The J2 values ​​were compared and the optimal proportional coefficient was taken as the one with the minimum J2 value at each vehicle speed. S4. Establishing a quantitative relationship expression between the vehicle speed u and the optimal proportional coefficient p by a fitting method; In step S2, the method for establishing the quantitative evaluation standard J1 of steering sensitivity in the medium and low speed range is: The yaw rate gain k and yaw rate overshoot under the steering wheel step input are To comprehensively evaluate the steering sensitivity, the expression is: （1） In the formula, a1 and a2 are k, The proportionality coefficient of In step S2, the method for establishing the quantitative evaluation standard J2 of handling stability in the medium and high speed range is: The vehicle's yaw rate w r , lateral acceleration a y and the center of mass slip angle To comprehensively evaluate the handling stability, the expression is: （2） Where k1, k2, and k3 are w r 、a y 、 The proportionality coefficient of The step S3 comprises the following steps: S3.

1. Obtain the optimal proportionality coefficient p at different vehicle speeds in the medium and low speed ranges; conduct steering wheel angle step tests at each selected vehicle speed, and obtain quantitative evaluation standard values ​​for the vehicle's steering sensitivity at different vehicle speeds corresponding to the different proportionality coefficients; S3.

2. Obtain the optimal proportionality coefficient p at different vehicle speeds in the medium and high speed range; conduct double lane change tests at the selected different speeds, and obtain quantitative evaluation standard values ​​for the vehicle's handling stability at different vehicle speeds corresponding to the different proportionality coefficients.

2. The method for selecting a proportional coefficient for a variable angular transmission ratio according to claim 1, characterized in that: The step S4 comprises the following steps: S4.

1. Establish a relationship between the optimal proportional coefficient p and vehicle speed u in the medium and low speed range. By fitting the nine sets of data obtained in step S3.1, the optimal proportional coefficient p at each vehicle speed in the medium and low speed range is obtained: （3） Where u is the vehicle speed, f1(u) is the multi-term function to be fitted; S4.

2. Establish a relationship between the optimal proportional coefficient p and vehicle speed u in the medium- and high-speed range. By fitting the 11 sets of data obtained in step S3.2, the optimal proportional coefficient p at each vehicle speed in the medium- and high-speed range is obtained: （4） Where u is the vehicle speed, and f2(u) is the multi-term function to be fitted.

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