A cruise control system and method based on internal model control

Abstract

The present invention discloses a cruise control method and system based on internal model control. After setting the target vehicle speed, the internal model controller module calculates the control vehicle speed, and executes the vehicle speed with the control vehicle speed as the vehicle speed execution target to obtain the actual vehicle speed; at the same time, the control vehicle speed is used as the input through the vehicle speed control estimation module to calculate the estimated vehicle speed after the vehicle speed is executed; the difference between the estimated vehicle speed and the actual vehicle speed is summed with the target vehicle speed, and the control vehicle speed is recalculated as the input of the internal model controller, and the above process is repeated to achieve low hysteresis following of the actual vehicle speed to the target vehicle speed. The present invention calculates the control vehicle speed that takes into account the response hysteresis of the vehicle speed execution process by summing the difference between the estimated vehicle speed and the actual vehicle speed with the target vehicle speed through the internal model controller module; the estimated vehicle speed is calculated by the vehicle speed control estimation module with the control vehicle speed as the input; finally, the vehicle speed is executed with the control vehicle speed as the vehicle speed execution target to obtain the actual vehicle speed, thereby achieving low hysteresis following control of the target vehicle speed.

Description

Technical Field

[0001] The present invention relates to the field of automobile cruise control, and in particular to a vehicle speed stabilization control of cruise control, which can be widely used in commercial vehicle models such as trucks, tractors, and hazardous chemicals vehicles. Background Art

[0002] The existing cruise control scheme usually uses the difference between the actual speed and the target speed, and uses the classic PID algorithm to calculate the speed adjustment amount. After the speed execution part calculates the incremental torque and the incremental injection amount, the speed adjustment amount is transmitted to the wheels by adjusting the injector injection, cylinder combustion and torque transmission, etc., to adjust the actual speed, and ultimately hope to achieve the actual speed following the target speed. At the same time, the PID parameters of the control need to be fully calibrated.

[0003] The speed adjustment amount calculated by the classic PID algorithm has changed after the speed execution process such as torque and injection amount calculation, injector injection, cylinder combustion and torque transmission. The speed adjustment amount calculated by the classic PID algorithm is not the current demand adjustment amount, that is, the calculated speed adjustment amount has a certain hysteresis relative to the demand adjustment amount. Therefore, when the classic PID algorithm is used for cruise control, the actual speed often has a certain volatility, which in turn affects the comfort and economy of the whole vehicle. Moreover, the more unreasonable the PID control parameter calibration is, the greater the volatility of the speed, and the greater the impact on the comfort and economy of the whole vehicle. Since the hysteresis in the speed execution process is objective, it is impossible to eliminate the fluctuation of the actual speed through the classic PID algorithm.

[0004] In addition, the mutual coupling between the parameters of the classic PID control leads to a large workload for PID parameter calibration, and the rationality of the calibration parameters has a great impact on the stability and smoothness of the vehicle speed control. In actual use, a large amount of calibration work will greatly extend the function development cycle, and the performance of the vehicle speed control may also be unstable. Summary of the invention

[0005] In view of the problems existing in the background technology, the purpose of the present invention is to propose a cruise control vehicle speed stability control system and method based on internal model control, which can reduce the influence of hysteresis in the vehicle speed execution process on the actual vehicle speed control, improve the following performance of the actual vehicle speed to the target vehicle speed, and reduce the fluctuation of the actual vehicle speed; at the same time, by reducing the calibration parameters, the calibration workload is reduced.

[0006] To achieve the above-mentioned purpose, the cruise control method based on internal model control designed by the present invention is characterized in that: after setting the target vehicle speed, the control vehicle speed is calculated, and the vehicle speed is executed with the control vehicle speed as the vehicle speed execution target to obtain the actual vehicle speed; at the same time, the control vehicle speed is used as input to calculate the estimated vehicle speed, and the difference between the estimated vehicle speed and the actual vehicle speed is positively fed back to the calculation of the control vehicle speed to realize the correction of the control vehicle speed.

[0007] Preferably, the controlled vehicle speed is calculated by an internal model controller, and the input is calculated by summing the difference between the estimated vehicle speed and the actual vehicle speed with the target vehicle speed.

[0008] As a preferred solution, a vehicle speed control estimation model is established according to the vehicle speed control response characteristics to achieve estimation from the controlled vehicle speed to the actual vehicle speed to obtain the estimated vehicle speed.

[0009] Preferably, the vehicle speed control estimation model is simplified to a second-order hysteresis object, and its transfer function is:

[0010]

[0011] Among them, T1 and T2 are time constants determined by the dominant pole of the vehicle speed execution part, θ is a pure lag link parameter determined by the delay time of the vehicle speed execution part, k is a constant related to the compression ratio and displacement, and s is a complex variable.

[0012] Further preferably, the parameters T1, T2, θ, and k are obtained by fitting experimental data.

[0013] Further preferably, the transfer function used in the vehicle speed calculation is:

[0014]

[0015] Among them, G m- (s) is G m (s), f(s) is the constructed filter, and the filter transfer function is:

[0016]

[0017] Where, T f is the filter time constant; r is an integer, and r should be selected so that G IMC (s) is the rational canonical transfer function, and the above parameters are obtained by calibration.

[0018] To achieve the above object, the cruise control system based on internal model control designed by the present invention is characterized by comprising:

[0019] The internal model controller module sums the difference between the estimated vehicle speed and the actual vehicle speed with the target vehicle speed, and uses the sum result to calculate the controlled vehicle speed;

[0020] A vehicle speed control estimation module estimates the vehicle speed by taking the controlled vehicle speed as input to obtain an estimated vehicle speed;

[0021] The vehicle speed execution module executes the vehicle speed with the controlled vehicle speed as the vehicle speed execution target to obtain the actual vehicle speed;

[0022] The difference between the estimated vehicle speed and the actual vehicle speed is positively fed back to the internal model controller module to realize the correction of the controlled vehicle speed.

[0023] Preferably, the vehicle speed execution module includes expected torque and fuel injection amount calculation, fuel injection, in-cylinder combustion and torque transmission parts.

[0024] Preferably, the controlled vehicle speed is calculated by an internal model controller module, and the input is the sum of the difference between the estimated vehicle speed and the actual vehicle speed and the target vehicle speed.

[0025] Preferably, the vehicle speed control estimation module is a vehicle speed estimation model established according to the response characteristics of the vehicle speed execution module, which realizes the estimation from the controlled vehicle speed to the actual vehicle speed. The vehicle speed control estimation model is simplified to a second-order hysteresis object, and its transfer function is:

[0026]

[0027] Among them, T1 and T2 are time constants determined by the dominant pole of the vehicle speed execution part, θ is a pure lag link parameter determined by the delay time of the vehicle speed execution part, k is a constant related to the compression ratio and displacement, and s is a complex variable.

[0028] Further preferably, the parameters T1, T2, θ, and k are obtained by fitting experimental data.

[0029] Further preferably, the internal model controller module calculates and controls the vehicle speed using a transfer function:

[0030]

[0031] Among them, G m- (s) is G m (s), f(s) is the constructed filter, and the filter transfer function is:

[0032]

[0033] Where, T f is the filter time constant; r is an integer, and r should be selected so that G IMC (s) is the rational canonical transfer function, and the above parameters are obtained by calibration.

[0034] After setting the target speed, the control speed is first calculated by the internal model controller, and the speed is executed with the control speed as the speed execution target to obtain the actual speed; at the same time, the speed control estimation module is used as the input to calculate the estimated speed after the speed execution; the difference between the estimated speed and the actual speed is summed with the target speed, and the control speed is recalculated as the input of the internal model controller, and the above process is repeated to achieve low-hysteresis following of the actual speed to the target speed. The present invention uses the internal model controller module to take the sum of the difference between the estimated speed and the actual speed and the target speed as input to calculate the control speed that takes into account the response hysteresis during the speed execution process; the estimated speed is calculated by the speed control estimation module with the control speed as input; finally, the speed is executed with the control speed as the speed execution target to obtain the actual speed, thereby achieving low-hysteresis following control of the target speed.

[0035] The beneficial effects of the present invention are as follows: the present invention adds an internal model controller module and a vehicle speed control estimation module, eliminates the PID control module, and reduces the calibration workload of model parameters; the internal model controller takes into account the response hysteresis in the vehicle speed execution process, sums the difference between the estimated vehicle speed and the actual vehicle speed with the target vehicle speed, calculates the controlled vehicle speed through the internal model controller module, and executes the vehicle speed with the controlled vehicle speed as the vehicle speed execution target to obtain the actual vehicle speed, thereby achieving low-hysteresis following control of the actual vehicle speed to the target vehicle speed, and reducing the influence of vehicle speed fluctuations on the comfort and economy of the entire vehicle.

[0036] The present invention establishes a vehicle speed control estimation model and constructs an internal model controller of the system; the internal model controller takes the sum of the difference between the target vehicle speed and the actual vehicle speed and the estimated vehicle speed as input, and outputs a controlled vehicle speed that takes into account the response hysteresis of the vehicle speed execution process; the vehicle speed execution target is used to execute the vehicle speed to obtain the actual vehicle speed, thereby achieving low-hysteresis following control of the actual vehicle speed to the target vehicle speed, and reducing the impact of vehicle speed fluctuations on the comfort and economy of the entire vehicle. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 is a control flow chart of the present invention;

[0038] Figure 2 It is a design operation flow chart of the inner model controller module of the present invention. DETAILED DESCRIPTION

[0039] The technical solution of the present invention (including the preferred technical solution) is further described in detail below by means of the accompanying drawings and by listing some optional embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0041] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0042] like Figure 1 and Figure 2 As shown, the cruise control system based on internal model control designed by the present invention includes:

[0043] The internal model controller module sums the difference between the estimated vehicle speed and the actual vehicle speed with the target vehicle speed, and uses the sum result to calculate the controlled vehicle speed;

[0044] A vehicle speed control estimation module estimates the vehicle speed by taking the controlled vehicle speed as input to obtain an estimated vehicle speed;

[0045] The vehicle speed execution module executes the vehicle speed with the controlled vehicle speed as the vehicle speed execution target to obtain the actual vehicle speed;

[0046] The difference between the estimated vehicle speed and the actual vehicle speed is positively fed back to the internal model controller to correct the controlled vehicle speed.

[0047] In some embodiments of the present invention, the controlled vehicle speed is calculated by an internal model controller module, and the input is the sum of the difference between the estimated vehicle speed and the actual vehicle speed and the target vehicle speed.

[0048] In some embodiments of the present invention, the desired torque and fuel injection amount calculation, fuel injection, in-cylinder combustion and torque transmission processes are integrated into a vehicle speed execution module.

[0049] After setting the target speed, the control speed is first calculated by the internal model controller, and the speed is executed with the control speed as the speed execution target to obtain the actual speed; at the same time, the control speed is used as input through the speed control estimation module to calculate the estimated speed after the speed execution; the difference between the estimated speed and the actual speed is summed with the target speed, and the control speed is recalculated as the input of the internal model controller, and the above process is repeated to achieve low-hysteresis following of the actual speed to the target speed.

[0050] The present invention uses an internal model controller module to take the sum of the difference between the estimated vehicle speed and the actual vehicle speed and the target vehicle speed as input, and calculates the controlled vehicle speed that takes into account the response hysteresis during the vehicle speed execution process; the estimated vehicle speed is calculated by using the controlled vehicle speed as input through a vehicle speed control estimation module; finally, the vehicle speed is executed with the controlled vehicle speed as the vehicle speed execution target to obtain the actual vehicle speed, thereby achieving control of the actual vehicle speed.

[0051] The vehicle speed after execution is estimated by the vehicle speed control estimation module, and the difference between the estimated vehicle speed and the actual vehicle speed is summed with the target vehicle speed, which is input into the internal model controller module to calculate the control vehicle speed that takes into account the response hysteresis of the vehicle speed execution process; the vehicle speed is executed with the control vehicle speed as the vehicle speed execution target to obtain the actual vehicle speed, thereby realizing low-hysteresis following control of the actual vehicle speed to the target vehicle speed.

[0052] Embodiment 1

[0053] During driving, the actual vehicle speed is 100 km / h. If the driver sets the target vehicle speed to 110 km / h, the control process of the present invention is as follows:

[0054] First, the internal model controller takes the target speed 110km / h as input to calculate the control speed v1. The speed control estimation module calculates the estimated speed v2. The difference between the estimated speed and the actual speed (v2-100) is fed back to the internal model controller to correct the control speed v1 and obtain the corrected control speed v 11 In addition, the vehicle speed execution module controls the vehicle speed v 11 The vehicle speed is executed for the vehicle speed execution target to realize the control of the actual vehicle speed.

[0055] Embodiment 2

[0056] During driving, the actual vehicle speed is 120 km / h, and the driver sets the target vehicle speed to 110 km / h. The control process of the present invention is as follows:

[0057] First, the internal model controller uses the target speed 110km / h as input to calculate the control speed v1. The speed control estimation module calculates the estimated speed v2. The difference between the estimated speed and the actual speed (v2-120) is fed back to the internal model controller to correct the control speed v1 and obtain the corrected control speed v 11 In addition, the vehicle speed execution module controls the vehicle speed v 11 The vehicle speed is executed for the vehicle speed execution target to realize the control of the actual vehicle speed.

[0058] Since the influence of response hysteresis has been considered at the input end of the vehicle speed execution module, the hysteresis between the actual vehicle speed and the target vehicle speed is greatly reduced after execution by the vehicle speed execution module, achieving better tracking between the actual vehicle speed and the target vehicle speed during cruising, and reducing the impact of vehicle speed fluctuations on the comfort and economy of the vehicle.

[0059] The speed control estimation module is a speed estimation model established according to the response characteristics of the speed execution module, which realizes the estimation from the controlled speed to the actual speed. The actual speed execution module is relatively complex and may be a high-order control system with large hysteresis characteristics. Taking into account the accuracy and practicality of the model, the model of the speed control estimation module can be simplified to a second-order hysteresis object, and its transfer function is:

[0060]

[0061] Among them, T1 and T2 are time constants determined by the dominant pole of the vehicle speed execution part, θ is a pure lag link parameter determined by the delay time of the vehicle speed execution part, k is a constant related to the compression ratio and displacement, and s is a complex variable. Preferably, the parameters T1, T2, θ, and k are obtained by fitting experimental data.

[0062] The model of the vehicle speed control estimation module is divided into two parts: G m (s) = G m+ (s)G m- (s); where G m+ (s) is G m (s) contains all delays and zeros in the right half plane, and its static gain is 1; G m- (s) is G m The minimum phase part of (s).

[0063] When calculating the controlled vehicle speed, the transfer function of the internal model controller module is:

[0064]

[0065] Among them, G m -(s) is G m(s), f(s) is the constructed filter, and the transfer function of the filter is:

[0066]

[0067] Where, T f is the filter time constant; r is an integer, and r should be selected so that G IMC (s) is the rational canonical transfer function, and the above parameters are obtained by calibration.

[0068] According to the dynamic response characteristics of vehicle speed, constants such as T1, T2, θ, k, etc. in the model can be determined, and then G m (s) Minimum phase part G m- (s), and the constant T f By calibrating r and r, a cruise control system based on internal model control can be established.

[0069] For a specific vehicle model, the dynamic characteristics of the expected torque and injection amount calculation, fuel injection, in-cylinder combustion and torque transmission are basically stable. Through experimental measurement, when the cruise is turned on, the actual vehicle speed output by the vehicle speed execution module changes with the input target vehicle speed. The recorded data is imported into MATLAB for model parameter identification, and the model parameters T1, T2, θ, k and other constants of the vehicle speed control estimation module are obtained.

[0070] After the vehicle speed control estimation module model is determined, the internal model controller module is designed.

[0071] First, according to the transfer function G of the vehicle speed control estimation module m (s), calculate G m The minimum phase partial transfer function G of (s) m -(s); The filter transfer function f(s) of the internal model controller module has been determined. To ensure that the internal model transfer function is a rational regular transfer function and that the system has good stability, its time constant T f and r should be fully calibrated, and r is an integer during calibration; after the filter f(s) is determined, the internal model controller transfer function is:

[0072]

[0073] After the internal model controller module is designed, the cruise control internal model controller is placed in the EECU. When the cruise state is activated, the target speed and the actual speed are read, and the speed control estimation module estimates the speed; the difference between the estimated speed and the actual speed is summed with the target speed and input into the internal model controller module, and the internal model controller module calculates the control speed taking into account the response hysteresis during the speed execution process; finally, the speed execution module takes the control speed as the execution target, calculates the expected torque and injection amount, performs fuel injection, in-cylinder combustion and torque transmission, and finally realizes high followability control of the actual speed and the target speed, reducing speed fluctuations.

[0074] The cruise control method based on internal model control designed by the present invention is characterized in that: after setting the target vehicle speed, the control vehicle speed is first calculated by the internal model controller module, and the vehicle speed is executed with the control vehicle speed as the vehicle speed execution target to obtain the actual vehicle speed; at the same time, the control vehicle speed is used as input, and the estimated vehicle speed is calculated by the vehicle speed estimation module, and the difference between the estimated vehicle speed and the actual vehicle speed is positively fed back to the internal model controller module to realize the correction of the control vehicle speed.

[0075] In some embodiments of the present invention, the controlled vehicle speed is calculated by an internal model controller, and the input is the sum of the difference between the estimated vehicle speed and the actual vehicle speed and the target vehicle speed.

[0076] As a preferred solution, a vehicle speed control estimation model is established according to the vehicle speed control response characteristics to achieve estimation from the controlled vehicle speed to the actual vehicle speed to obtain the estimated vehicle speed.

[0077] Preferably, the vehicle speed control estimation model is simplified to a second-order hysteresis object, and its transfer function is:

[0078]

[0079] Among them, T1 and T2 are time constants determined by the dominant pole of the vehicle speed execution part, θ is a pure lag link parameter determined by the delay time of the vehicle speed execution part, k is a constant related to the compression ratio and displacement, and s is a complex variable. Preferably, the parameters T1, T2, θ, and k are obtained by fitting experimental data.

[0080] The vehicle speed control estimation model is divided into two parts: G m (s) = G m+ (s)G m- (s); where G m+ (s) is G m (s) contains all delays and zeros in the right half plane, and its static gain is 1; G m- (s) is G m The minimum phase part of (s).

[0081] Further preferably, when calculating the controlled vehicle speed, the transfer function of the internal model controller module is:

[0082]

[0083] Among them, G m -(s) is G m (s), f(s) is the constructed filter, and the transfer function of the filter is:

[0084]

[0085] Where, T f is the filter time constant; r is an integer, and r should be selected so that G IMC (s) is the rational canonical transfer function, and the above parameters are obtained by calibration.

[0086] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0087] Those skilled in the art will readily appreciate that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, combinations, replacements, improvements, etc. made within the spirit and principles of the present invention are included within the protection scope of the present invention.

Claims

1. A cruise control method based on internal model control, characterized in that: After setting the target speed, the controlled speed is calculated, and the speed is executed with the controlled speed as the speed execution target to obtain the actual speed; at the same time, the estimated speed is calculated with the controlled speed as input; Among them: The transfer function for calculating the control speed is: Among them, G m- (s) is G m (s) is the minimum phase part, f(s) is the constructed filter; The vehicle speed is estimated by taking the controlled vehicle speed as input to obtain the estimated vehicle speed, thus realizing the estimation from the controlled vehicle speed to the actual vehicle speed; it is simplified into a second-order hysteresis object, and its transfer function is: Among them, T1 and T2 are time constants determined by the dominant pole of the vehicle speed execution part, θ is the pure lag link parameter determined by the delay time of the vehicle speed execution part, k is a constant related to the compression ratio and displacement, and s is a complex variable; The difference between the estimated vehicle speed and the actual vehicle speed is positively fed back into the calculation of the controlled vehicle speed, and the controlled vehicle speed is recalculated after being summed with the target vehicle speed to achieve correction of the controlled vehicle speed.

2. The cruise control method based on internal model control according to claim 1, characterized in that: The parameters T1, T2, θ, and k are obtained by fitting the experimental data.

3. The cruise control method based on internal model control according to claim 1, characterized in that: The transfer function of the filter is: Where, T f is the filter time constant; r is an integer, and r should be selected so that G IMC (s) is the rational canonical transfer function, and the above parameters are obtained by calibration.

4. A cruise control system based on internal model control, characterized in that: include: The vehicle speed control estimation module uses the controlled vehicle speed as input to estimate the vehicle speed and obtain the estimated vehicle speed. Its transfer function is: Among them, T1 and T2 are time constants determined by the dominant pole of the vehicle speed execution part, θ is the pure lag link parameter determined by the delay time of the vehicle speed execution part, k is a constant related to the compression ratio and displacement, and s is a complex variable; The vehicle speed execution module executes the vehicle speed with the controlled vehicle speed as the vehicle speed execution target to obtain the actual vehicle speed; The internal model controller module is used to calculate the control speed by using the transfer function with the target speed as input; receive the difference between the estimated speed and the actual speed, and sum it with the target speed, and recalculate the control speed using the sum result; the transfer function for calculating the control speed is: Among them, G m- (s) is G m (s) is the minimum phase part, f(s) is the constructed filter; The difference between the estimated vehicle speed and the actual vehicle speed is positively fed back to the internal model controller module to recalculate the controlled vehicle speed, thereby realizing the correction of the controlled vehicle speed.

5. The cruise control method based on internal model control according to claim 4, characterized in that: The parameters T1, T2, θ, and k are obtained by fitting the experimental data.

6. The cruise control method based on internal model control according to claim 4, characterized in that: The transfer function of the filter is: Where, T f is the filter time constant; r is an integer, and r should be selected so that G IMC (s) is the rational canonical transfer function, and the above parameters are obtained by calibration.

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