EPS power assist curve control method and device

Abstract

The present application relates to an EPS power assist curve control method and device, and relates to the field of vehicle control technology. The method includes the following steps: detecting the slope value of the current driving road to obtain the current road slope value; comparing the current road slope value with a preset first slope threshold and a second slope threshold to obtain a slope comparison result; based on the slope comparison result, selecting a corresponding EPS power assist curve from a plurality of preset EPS power assist curves; and controlling the EPS system based on the selected EPS power assist curve. The present application configures a suitable EPS power assist curve based on different slope values. When the vehicle is driving, the slope value of the road on which the vehicle is driving is monitored, and a suitable EPS power assist curve is selected based on the slope value to control the EPS to ensure driving safety.

Description

Technical Field

[0001] The present application relates to the field of vehicle control technology, and in particular to a method and device for regulating an EPS power assist curve. Background Art

[0002] The EPS power assist curve is based on different vehicle speeds and different steering wheel input torques. The ECU controls the current of the power assist motor to meet the needs of power assist torque under different driving conditions. The EPS power assist curve considers the working conditions mostly for debugging on straight roads or stable roads. However, it is difficult to ensure the same feel on all roads when verifying on other working conditions such as icy roads, split roads, and sloped roads.

[0003] In actual driving, because the slope is too large, the mass of the vehicle will be transferred between the front and rear axles. When it is fully loaded and the mass of the vehicle is large, it will have a great impact on the steering feel. Therefore, the traditional EPS power assist curve control method has certain defects.

[0004] Therefore, how to consider the influencing factors of slope and meet the current EPS assist curve control needs is a technical problem that needs to be solved urgently. Summary of the invention

[0005] The present application provides an EPS assist curve control method and device, which configures a suitable EPS assist curve based on different slope values. When the vehicle is driving, the slope value of the road surface on which the vehicle is driving is monitored, and a suitable EPS assist curve is selected based on the slope value to control the EPS to ensure driving safety.

[0006] To achieve the above objectives, this application provides the following solutions.

[0007] In a first aspect, the present application provides an EPS power assist curve control method, the method comprising the following steps:

[0008] Detect the slope value of the current driving road and obtain the current road slope value;

[0009] Comparing the current road slope value with a preset first slope threshold and a second slope threshold to obtain a slope comparison result;

[0010] Based on the slope comparison result, a corresponding EPS power assist curve is selected from a plurality of preset EPS power assist curves;

[0011] Based on the selected EPS assist curve, the EPS system is controlled.

[0012] Specifically, it is assumed that the value of the first slope threshold is a, and the value of the second slope threshold is b;

[0013] The slope sensor detects the slope. When the slope is greater than the preset slope value a, the EPS automatically calls the debugged EPS power assist curve 2, i.e. the second EPS power assist curve, according to the slope sensor signal.

[0014] When the slope value is less than the preset value b, EPS automatically calls the debugged EPS power assist curve 3, i.e. the third EPS power assist curve, according to the slope sensor signal;

[0015] When it is between the preset slope value a and the preset slope value b, EPS automatically calls the debugged EPS assist curve 1 according to the slope sensor signal, that is, the first EPS assist curve. This curve is a curve debugged on a normal road surface. This curve can be a comprehensive curve verified under other working conditions.

[0016] Further, the selecting a corresponding EPS power assist curve from a plurality of preset EPS power assist curves based on the slope comparison result comprises the following steps:

[0017] When the current road slope value is between the first slope threshold and the second slope threshold, selecting a preset first EPS assist curve;

[0018] When the current road slope value is greater than the first slope threshold, selecting a preset second EPS assist curve;

[0019] When the current road slope value is less than the second slope threshold, a preset third EPS assist curve is selected.

[0020] Furthermore, the method further comprises the following steps:

[0021] The EPS assist curve is formulated based on the steering wheel torque value when the EPS system starts to provide assist, the steering wheel torque value when the EPS system provides the maximum assist torque, the gradient of the EPS assist characteristic curve, and the slope sensitivity coefficient.

[0022] Furthermore, the method also includes a slope induction coefficient calculation formula;

[0023] The slope induction coefficient calculation formula is:

[0024] in,

[0025] K2 is the slope induction coefficient;

[0026] T period is the expected steering wheel torque value;

[0027] Tf is the steering wheel torque value when the EPS system starts to provide power assistance;

[0028] Tmax is the steering wheel torque value when the EPS system provides maximum assist torque.

[0029] Specifically, the value of the T period is configured as the difference between the steering wheel torque without a slope sensor and the steering wheel torque with a slope sensor under the same working condition.

[0030] Specifically, the value of the T period is configured as the maximum value of the steering wheel torque when a ramp sensor is provided.

[0031] In a second aspect, the present application provides an EPS power assist curve control device, the device comprising:

[0032] A slope value detection module is used to detect the slope value of the current driving road and obtain the current road slope value;

[0033] A slope comparison module, which is used to compare the current road slope value with a preset first slope threshold and a second slope threshold to obtain a slope comparison result;

[0034] A curve selection module, which is used to select a corresponding EPS power assist curve from a plurality of preset EPS power assist curves based on the slope comparison result;

[0035] The EPS control module is used to control the EPS system based on the selected EPS power assist curve.

[0036] Specifically, it is assumed that the value of the first slope threshold is a, and the value of the second slope threshold is b;

[0037] The slope sensor detects the slope. When the slope is greater than the preset slope value a, the EPS automatically calls the debugged EPS power assist curve 2, i.e. the second EPS power assist curve, according to the slope sensor signal.

[0038] When the slope value is less than the preset value b, EPS automatically calls the debugged EPS power assist curve 3, i.e. the third EPS power assist curve, according to the slope sensor signal;

[0039] When it is between the preset slope value a and the preset slope value b, EPS automatically calls the debugged EPS assist curve 1 according to the slope sensor signal, that is, the first EPS assist curve. This curve is a curve debugged on a normal road surface. This curve can be a comprehensive curve verified under other working conditions.

[0040] Furthermore, the slope comparison module is further configured to select a preset first EPS assist curve when the current road slope value is between the first slope threshold and the second slope threshold;

[0041] The slope comparison module is further used to select a preset second EPS assist curve when the current road slope value is greater than the first slope threshold;

[0042] The slope comparison module is also used to select a preset third EPS assist curve when the current road slope value is less than the second slope threshold.

[0043] Furthermore, the device also includes:

[0044] The curve formulation module is used to formulate an EPS assist curve based on the steering wheel torque value when the EPS system starts to provide assist, the steering wheel torque value when the EPS system provides maximum assist torque, the EPS assist characteristic curve gradient and the slope induction coefficient.

[0045] Furthermore, the device is also provided with a slope induction coefficient calculation formula;

[0046] The slope induction coefficient calculation formula is:

[0047] in,

[0048] K2 is the slope induction coefficient;

[0049] T period is the expected steering wheel torque value;

[0050] Tf is the steering wheel torque value when the EPS system starts to provide power assistance;

[0051] Tmax is the steering wheel torque value when the EPS system provides maximum assist torque.

[0052] Specifically, the value of the T period is configured as the difference between the steering wheel torque without a slope sensor and the steering wheel torque with a slope sensor under the same working condition.

[0053] Specifically, the value of the T period is configured as the maximum value of the steering wheel torque when a ramp sensor is provided.

[0054] The beneficial effects of the technical solution provided by this application include:

[0055] The present application configures a suitable EPS assist curve based on different slope values. When the vehicle is driving, the slope value of the road on which the vehicle is driving is monitored, and a suitable EPS assist curve is selected based on the slope value to control the EPS to ensure driving safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Terminology explanation:

[0057] EPS: Electric Power Steering, electric power steering system.

[0058] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0059] Figure 1 This is a flowchart of the steps of the EPS power assist curve control method provided in the embodiment of the present application;

[0060] Figure 2 This is a structural block diagram of the EPS power assist curve control device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0062] The embodiments of the present application are further described in detail below in conjunction with the accompanying drawings.

[0063] The embodiment of the present application provides an EPS assist curve control method and device, which configures a suitable EPS assist curve based on different slope values. When the vehicle is driving, the slope value of the road surface on which the vehicle is driving is monitored, and a suitable EPS assist curve is selected based on the slope value to control the EPS to ensure driving safety.

[0064] In order to achieve the above technical effects, the overall idea of ​​this application is as follows:

[0065] A method for regulating an EPS power assist curve, the method comprising the following steps:

[0066] S1. Detect the slope value of the current driving road and obtain the current road slope value;

[0067] S2. Compare the current road slope value with a preset first slope threshold and a second slope threshold to obtain a slope comparison result;

[0068] S3. Based on the slope comparison result, a corresponding EPS power assist curve is selected from a plurality of preset EPS power assist curves;

[0069] S4. Control the EPS system based on the selected EPS assist curve.

[0070] The embodiments of the present application are further described in detail below in conjunction with the accompanying drawings.

[0071] See also Figure 1 As shown, the embodiment of the present application provides an EPS power assist curve control method, the method comprising the following steps:

[0072] S1. Detect the slope value of the current driving road and obtain the current road slope value;

[0073] S2. Compare the current road slope value with a preset first slope threshold and a second slope threshold to obtain a slope comparison result;

[0074] S3. Based on the slope comparison result, a corresponding EPS power assist curve is selected from a plurality of preset EPS power assist curves;

[0075] S4. Control the EPS system based on the selected EPS assist curve.

[0076] In an embodiment of the present application, a suitable EPS assist curve is configured based on different slope values. When the vehicle is driving, the slope value of the road surface on which the vehicle is driving is monitored, and a suitable EPS assist curve is selected based on the slope value to control EPS to ensure driving safety.

[0077] Further, the selecting a corresponding EPS power assist curve from a plurality of preset EPS power assist curves based on the slope comparison result comprises the following steps:

[0078] When the current road slope value is between the first slope threshold and the second slope threshold, selecting a preset first EPS assist curve;

[0079] When the current road slope value is greater than the first slope threshold, selecting a preset second EPS assist curve;

[0080] When the current road slope value is less than the second slope threshold, a preset third EPS assist curve is selected.

[0081] Specifically, it is assumed that the value of the first slope threshold is a, and the value of the second slope threshold is b;

[0082] The slope sensor detects the slope. When the slope is greater than the preset slope value a, the EPS automatically calls the debugged EPS power assist curve 2, i.e. the second EPS power assist curve, according to the slope sensor signal.

[0083] When the slope value is less than the preset value b, EPS automatically calls the debugged EPS power assist curve 3, i.e. the third EPS power assist curve, according to the slope sensor signal;

[0084] When it is between the preset slope value a and the preset slope value b, EPS automatically calls the debugged EPS assist curve 1 according to the slope sensor signal, that is, the first EPS assist curve. This curve is a curve debugged on a normal road surface. This curve can be a comprehensive curve verified under other working conditions.

[0085] Among them, the slope EPS assist characteristic curve is mainly described by the following parameters:

[0086] 1) Steering wheel torque value Tf when the EPS system starts to provide power assistance;

[0087] 2) Steering wheel torque value Tmax when the EPS system provides maximum assist torque;

[0088] 3) EPS power assist characteristic curve gradient K1;

[0089] 4) Slope sensitivity coefficient K2.

[0090] Combined with the analysis of the steering wheel torque without a slope sensor, it can be concluded that the torque range of the steering wheel with a slope sensor is roughly (1.5-4)Nm, and the value is a schematic value. The slope sensitivity coefficient K2 can be calculated by the following expression:

[0091]

[0092] The steering wheel torque corresponding to period T is the difference between the analysis of the steering wheel torque without the slope sensor and the steering wheel torque with the slope sensor, which is the expected steering wheel torque value;

[0093] At the same time, in order to enable the driver to have a certain road feel, the steering wheel power torque T with a ramp sensor is taken as the maximum power torque. When the driver's actual steering wheel torque reaches the maximum value Tmax, the EPS electric power steering system will provide the maximum power torque.

[0094] Matlab or simulink can be used for simulation, and the slope induction coefficient K2 can be simulated and analyzed by combining the vehicle speed at each stage;

[0095] Then the fitting is performed to obtain the relationship between the vehicle speed and the slope induction coefficient K2. After the expression of the vehicle speed induction coefficient K2 is fitted, the fitting effect is analyzed. The relevant evaluation index values ​​are generated by the matlab CurveFitting Tool system, as follows:

[0096] Square root error SSE = 0.0026;

[0097] Error system R = 0.9766;

[0098] The equation fitting coefficient AR = 0.955;

[0099] RMS error = 0.03;

[0100] It is more reasonable to use cubic fitting with reference to the above rating indicators to make the EPS assist characteristic curve of the downhill sensor in the full speed range.

[0101] Furthermore, the method further comprises the following steps:

[0102] The EPS assist curve is formulated based on the steering wheel torque value when the EPS system starts to provide assist, the steering wheel torque value when the EPS system provides the maximum assist torque, the gradient of the EPS assist characteristic curve, and the slope sensitivity coefficient.

[0103] Furthermore, the method also includes a slope induction coefficient calculation formula;

[0104] The slope induction coefficient calculation formula is:

[0105] in,

[0106] K2 is the slope induction coefficient;

[0107] T period is the expected steering wheel torque value;

[0108] Tf is the steering wheel torque value when the EPS system starts to provide power assistance;

[0109] Tmax is the steering wheel torque value when the EPS system provides maximum assist torque.

[0110] Specifically, the value of the T period is configured as the difference between the steering wheel torque without a slope sensor and the steering wheel torque with a slope sensor under the same working condition.

[0111] Specifically, the value of the T period is configured as the maximum value of the steering wheel torque when a ramp sensor is provided.

[0112] See also Figure 2 As shown, based on the same inventive concept as the method embodiment, the embodiment of the present application provides an EPS power assist curve control device, which includes:

[0113] A slope value detection module is used to detect the slope value of the current driving road and obtain the current road slope value;

[0114] A slope comparison module, which is used to compare the current road slope value with a preset first slope threshold and a second slope threshold to obtain a slope comparison result;

[0115] A curve selection module, which is used to select a corresponding EPS power assist curve from a plurality of preset EPS power assist curves based on the slope comparison result;

[0116] The EPS control module is used to control the EPS system based on the selected EPS power assist curve.

[0117] In an embodiment of the present application, a suitable EPS assist curve is configured based on different slope values. When the vehicle is driving, the slope value of the road surface on which the vehicle is driving is monitored, and a suitable EPS assist curve is selected based on the slope value to control EPS to ensure driving safety.

[0118] Furthermore, the slope comparison module is further configured to select a preset first EPS assist curve when the current road slope value is between the first slope threshold and the second slope threshold;

[0119] The slope comparison module is further used to select a preset second EPS assist curve when the current road slope value is greater than the first slope threshold;

[0120] The slope comparison module is also used to select a preset third EPS assist curve when the current road slope value is less than the second slope threshold.

[0121] Specifically, it is assumed that the value of the first slope threshold is a, and the value of the second slope threshold is b;

[0122] The slope sensor detects the slope. When the slope is greater than the preset slope value a, the EPS automatically calls the debugged EPS power assist curve 2, i.e. the second EPS power assist curve, according to the slope sensor signal.

[0123] When the slope value is less than the preset value b, EPS automatically calls the debugged EPS power assist curve 3, i.e. the third EPS power assist curve, according to the slope sensor signal;

[0124] When it is between the preset slope value a and the preset slope value b, EPS automatically calls the debugged EPS assist curve 1 according to the slope sensor signal, that is, the first EPS assist curve. This curve is a curve debugged on a normal road surface. This curve can be a comprehensive curve verified under other working conditions.

[0125] Among them, the slope EPS assist characteristic curve is mainly described by the following parameters:

[0126] 1) Steering wheel torque value Tf when the EPS system starts to provide power assistance;

[0127] 2) Steering wheel torque value Tmax when the EPS system provides maximum assist torque;

[0128] 3) EPS power assist characteristic curve gradient K1;

[0129] 4) Slope sensitivity coefficient K2.

[0130] Combined with the analysis of the steering wheel torque without a slope sensor, it can be concluded that the torque range of the steering wheel with a slope sensor is roughly (1.5-4)Nm, and the value is a schematic value. The slope sensitivity coefficient K2 can be calculated by the following expression:

[0131]

[0132] The steering wheel torque corresponding to period T is the difference between the analysis of the steering wheel torque without the slope sensor and the steering wheel torque with the slope sensor;

[0133] At the same time, in order to enable the driver to have a certain road feel, the steering wheel power torque T with a ramp sensor is taken as the maximum power torque. When the driver's actual steering wheel torque reaches the maximum value Tmax, the EPS electric power steering system will provide the maximum power torque.

[0134] Matlab or simulink can be used for simulation, and the slope induction coefficient K2 can be simulated and analyzed by combining the vehicle speed at each stage;

[0135] Then the fitting is performed to obtain the relationship between the vehicle speed and the slope induction coefficient K2. After the expression of the vehicle speed induction coefficient K2 is fitted, the fitting effect is analyzed. The relevant evaluation index values ​​are generated by the matlab CurveFitting Tool system, as follows:

[0136] Square root error SSE = 0.0026;

[0137] Error system R = 0.9766;

[0138] The equation fitting coefficient AR = 0.955;

[0139] RMS error = 0.03;

[0140] It is more reasonable to use cubic fitting with reference to the above rating indicators to make the EPS assist characteristic curve of the downhill sensor in the full speed range.

[0141] Furthermore, the device also includes:

[0142] The curve formulation module is used to formulate an EPS assist curve based on the steering wheel torque value when the EPS system starts to provide assist, the steering wheel torque value when the EPS system provides maximum assist torque, the EPS assist characteristic curve gradient and the slope induction coefficient.

[0143] Furthermore, the device is also provided with a slope induction coefficient calculation formula;

[0144] The slope induction coefficient calculation formula is:

[0145] in,

[0146] K2 is the slope induction coefficient;

[0147] T period is the expected steering wheel torque value;

[0148] Tf is the steering wheel torque value when the EPS system starts to provide power assistance;

[0149] Tmax is the steering wheel torque value when the EPS system provides maximum assist torque.

[0150] Specifically, the value of the T period is configured as the difference between the steering wheel torque without a slope sensor and the steering wheel torque with a slope sensor under the same working condition.

[0151] Specifically, the value of the T period is configured as the maximum value of the steering wheel torque when a ramp sensor is provided.

[0152] It should be noted that the EPS power assist curve control device provided in the embodiment of the present application, and its corresponding technical problems, technical means and technical effects are similar to the principles of the EPS power assist curve control method in terms of principle.

[0153] It should be noted that, in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0154] The above is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A method for regulating EPS power assist curve, characterized in that: The method comprises the following steps: Detect the slope value of the current driving road and obtain the current road slope value; Comparing the current road slope value with a preset first slope threshold and a second slope threshold to obtain a slope comparison result; Based on the slope comparison result, a corresponding EPS power assist curve is selected from a plurality of preset EPS power assist curves; Controlling the EPS system based on the selected EPS power assist curve; The method further comprises the following steps: The EPS assist curve is formulated based on the steering wheel torque value when the EPS system starts to provide assist, the steering wheel torque value when the EPS system provides the maximum assist torque, the EPS assist characteristic curve gradient and the slope induction coefficient; The method also includes a slope induction coefficient calculation formula; The slope induction coefficient calculation formula is: in, K2 is the slope induction coefficient; T period is the expected steering wheel torque value; Tf is the steering wheel torque value when the EPS system starts to provide power assistance; Tmax is the steering wheel torque value when the EPS system provides maximum assist torque.

2. The EPS power assist curve control method according to claim 1, characterized in that: The step of selecting a corresponding EPS power assist curve from a plurality of preset EPS power assist curves based on the slope comparison result comprises the following steps: When the current road slope value is between the first slope threshold and the second slope threshold, selecting a preset first EPS assist curve; When the current road slope value is greater than the first slope threshold, selecting a preset second EPS assist curve; When the current road slope value is less than the second slope threshold, a preset third EPS assist curve is selected.

3. The EPS power assist curve control method according to claim 1, characterized in that: The value of the T period is configured as the difference between the steering wheel torque without a slope sensor and the steering wheel torque with a slope sensor under the same working condition.

4. The EPS power assist curve control method according to claim 1, characterized in that: The value of the T period is configured as the maximum value of the steering wheel torque when a slope sensor is provided.

5. An EPS power assist curve control device, characterized in that: The device comprises: A slope value detection module is used to detect the slope value of the current driving road and obtain the current road slope value; A slope comparison module, which is used to compare the current road slope value with a preset first slope threshold and a second slope threshold to obtain a slope comparison result; A curve selection module, which is used to select a corresponding EPS power assist curve from a plurality of preset EPS power assist curves based on the slope comparison result; An EPS control module, which is used to control the EPS system based on the selected EPS power assist curve; The device also includes: A curve formulation module, which is used to formulate an EPS power-assistance curve based on a steering wheel torque value when the EPS system starts to provide power assistance, a steering wheel torque value when the EPS system provides a maximum power-assistance torque, an EPS power-assistance characteristic curve gradient, and a slope induction coefficient; The device is also equipped with a slope induction coefficient calculation formula; The slope induction coefficient calculation formula is: in, K2 is the slope induction coefficient; T period is the expected steering wheel torque value; Tf is the steering wheel torque value when the EPS system starts to provide power assistance; Tmax is the steering wheel torque value when the EPS system provides maximum assist torque.

6. The EPS power assist curve control device according to claim 5, characterized in that: The slope comparison module is further configured to select a preset first EPS assist curve when the current road slope value is between the first slope threshold and the second slope threshold; The slope comparison module is further used to select a preset second EPS assist curve when the current road slope value is greater than the first slope threshold; The slope comparison module is also used to select a preset third EPS assist curve when the current road slope value is less than the second slope threshold.

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