WO2016095106A1

WO2016095106A1 - Method and system for determining working state of vehicle in traction state

Info

Publication number: WO2016095106A1
Application number: PCT/CN2014/093957
Authority: WO
Inventors: 徐国卿; 徐坤
Original assignee: 中国科学院深圳先进技术研究院
Priority date: 2014-12-16
Filing date: 2014-12-16
Publication date: 2016-06-23

Abstract

A method and system for determining the working state of a vehicle in a traction state. The method comprises: measuring an output torque T of a vehicle motor and a wheel speed ω; estimating a adhesion moment T_d; calculating an output torque change value ΔT and an adhesion moment change value ΔT_d; and determining the working state of the vehicle according to the output torque change value ΔT and the adhesion moment change value ΔT_d. According to the method and the system, the working state of the vehicle in the traction state can be determined by just measuring the output torque output by the vehicle motor to wheels as well as wheel speed information, the determining process is simple and reliable, and output parameters in the method can be used in a vehicle slip control process. In addition, few sensors are needed, the implementation costs are low, and the reliability is high.

Description

A method and system for judging the working state of a vehicle in a traction state

Technical field

The invention relates to the technical field of vehicle working state detection, in particular to a method and system for judging the working state of a vehicle in a traction state.

Background technique

In the process of vehicle traction operation or braking control, when the driving force or braking force transmitted by the power system to the tire exceeds the critical value of the adhesion between the tire and the road (the maximum static friction force of the vehicle on the ground), the tire of the vehicle will idling Phenomenon, this phenomenon is the vehicle's unsteady working state (vehicle slipping state). Once the vehicle slips, the critical value of the maximum static friction between the vehicle and the ground will decrease, the ground dynamic friction resistance of the vehicle will decrease, the reaction force of the road to the vehicle will drop sharply, and the critical driving force for tire skidding will decrease. Whether it is in the process of car traction operation or braking control, when the car is in a slipping and unstable working state, it will seriously damage the safety and controllability of car driving. It is very important for the vehicle to ensure that the wheels of the vehicle are in a stable working state under different ground conditions.

The traditional judgment of vehicle stability is mainly based on the identification of the current slip rate and the judgment of the optimal slip rate. At present, many researchers have conducted a lot of research on the slip rate λ. The research results can be roughly divided into two categories: The class is to obtain the slip rate λ directly through the relationship between the vehicle chassis speed (the actual vehicle speed) and the wheel speed (wheel linear speed), and judge the stability of the vehicle through the slip rate and the change of the friction coefficient. It can be seen from the slip rate formula that the slip rate λ of a vehicle has a nonlinear relationship with the difference between the wheel speed and the vehicle chassis speed. Therefore, to obtain the slip rate parameters of the vehicle directly, the wheel speed and chassis speed must be accurately obtained. For the vehicle chassis speed, although there are many measurement methods at present, the sensor's sensitivity to the environment, high cost, and measurement accuracy limit the practical application, and vehicle vibration will also have a greater impact on the measurement results. The second type is called the state observer method, which obtains the relationship between wheel speed and slip rate λ through the wheel motion equation, estimates the current slip rate, judges the optimal slip rate under the current tire and road conditions, and then judges the working state of the vehicle This method avoids the parameter of vehicle speed, but the accuracy of this method is poor when the vehicle is in a low-speed state, and its practicability is not high. Moreover, the optimal slip rate is different under different tire and road contact conditions, which is difficult to judge in real time, and has very large limitations in practical applications, and the practical application effect is not good.

Summary of the invention

For this reason, the technical problem to be solved by the present invention is that the current common vehicle working state detection methods have technical problems that the actual vehicle speed cannot be accurately measured, or the judgment effect is not good when the vehicle is in a low speed state, and the optimal slip rate is difficult to judge in real time. Therefore, a method that can accurately identify the traction state only needs to measure the output torque of the vehicle motor and the wheel speed. To A method to determine whether the vehicle is in a stable working state or an unsteady working state.

In order to solve the above technical problems, the present invention provides the following technical solutions:

A method for judging the working state of a vehicle in a traction state, including:

Measure the output torque T of the vehicle motor and the wheel speed ω;

Estimate the adhesion moment T _d ;

Calculate the output torque change value ΔT and the adhesion torque change value ΔT _d ;

According to the output torque change value ΔT and the adhesion torque change value ΔT _d , the vehicle working state in the traction state is judged.

As an optimization, before measuring the output torque T and wheel speed ω of the vehicle motor, it also includes:

Initialize the inertia constant J of the vehicle, which is related to the parameters of the vehicle.

As an optimization, before estimating the adhesion torque T _d, it also includes:

Filter the wheel speed ω.

As an optimization, the output torque T is obtained by measuring the input current of the motor. In the constant current state, the output torque T is equal to the product of the torque constant and the input current of the motor.

As an optimization, the adhesion torque T _d is based on the formula

Estimated, where

Is the derivative of the wheel speed ω.

As an optimization, according to the output torque change value ΔT and the adhesion torque change value ΔT _d , the working state of the vehicle in the traction state is judged, including:

When the output torque change value ΔT>0 and the adhesion torque change value ΔT _d >0, or when the output torque change value ΔT<0 and the adhesion torque change value ΔT _d <0, or when the output torque change value When ΔT=0 and the change value of adhesion torque ΔT _d >=0, it is determined that the vehicle in the traction state is in a stable working state;

When the output torque change value ΔT>0 and the adhesion torque change value ΔT _d <0, or when the output torque change value ΔT<0 and the adhesion torque change value ΔT _d >0, or when the output torque change value When ΔT=0 and the adhesion torque change value ΔT _d <0, it is determined that the vehicle in the traction state is in an unstable working state.

In the case of △T≠0,

when

And

When it is determined that the vehicle is in a critical transition state that is about to transition from a stable working state to an unsteady working state;

when

And

When, determine that the vehicle is in a stable working state;

when

And

When, determine that the vehicle is in an unstable working state;

when

And

When it is time, it is determined that the vehicle is at the critical transition point from the unstable working state to the stable working state;

In the case of △T=0,

When △T _d <0, it is determined that the vehicle is in an unstable working state;

When △T _d >=0, it is determined that the vehicle is in a stable working state;

Among them, ΔT(k) is the current calculated output torque change value, ΔT(k-1) is the last calculated output torque change value, ΔT _d (k) is the current calculated adhesion torque change value , ΔT _d (k-1) is the change value of the adhesion torque calculated last time.

As an optimization, the step of judging the working state of the vehicle in the traction state according to the output torque change value ΔT and the adhesion torque change value ΔT _d further includes: real-time determination of whether to limit the output torque T according to the determined vehicle working state control.

As an optimization, real-time determination of whether to implement limiting control on the output torque T according to the determined vehicle working state includes:

When it is determined that the vehicle is in an unsteady working state, the output torque T is controlled by limiting;

When it is determined that the vehicle is in a stable working state, the output torque T is not subject to limit control.

A system for judging the working state of a vehicle in a traction state, including:

The measurement module is used to measure the output torque T and wheel speed ω of the vehicle motor;

Estimation module for estimating the adhesion moment T _d ;

The calculation module is used to calculate the output torque change value ΔT and the adhesion torque change value ΔT _d ;

The judgment module is used to judge the working state of the vehicle in the traction state according to the output torque change value ΔT and the adhesion torque change value ΔT _d.

As an optimization, the system for judging the working status of the vehicle also includes:

The initialization module is used to obtain the inertia constant J of the vehicle; and/or

The filter module is used to filter the measured wheel speed ω; and/or

The limiter module is used to limit the output torque T when the vehicle in the traction state is in an unstable working state.

Compared with the prior art, the above-mentioned technical solution of the present invention has the following advantages:

The invention provides a method and system for judging the working state of a vehicle in a traction state. Based on the physical and mechanical theory of the vehicle slipping process, it only needs to measure the output torque of the vehicle motor to the wheels and wheel speed information to judge the state of the traction. The vehicle working state does not need to know the vehicle chassis speed and slip rate values, the determination process is simple and reliable, and the output parameters of this method can be used in the vehicle slip control process. This method is very suitable for the practical application of vehicle control. In addition, fewer sensors are required, implementation costs are low, and reliability is high. The invention is also suitable for detecting the slip state of four-wheel drive vehicles driven by motors and various robots and machine exoskeletons driven by motors.

Description of the drawings

FIG. 1 is a flowchart of a method for judging the working state of a vehicle in a traction state according to an embodiment of the present invention;

Figure 2 is a diagram of the relationship between the slip rate λ and the friction coefficient μ when the vehicle is on different roads;

Figure 3 is a schematic diagram of the force distribution when the wheel is working;

4 is a flowchart of a method for judging the working state of a vehicle in a towing state according to another embodiment of the present invention;

Fig. 5 is a schematic diagram of a system for judging the working state of a vehicle in a towing state according to an embodiment of the present invention.

Detailed ways

In order to enable those skilled in the art to better understand the solution of the present invention, the technical solution provided by the present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

In the following embodiments, d/dt represents the derivative of the variable; △ represents the small signal, which refers to the change at the time of detection.

Example 1

Fig. 1 shows a flowchart of a method for judging the working state of a vehicle in a traction state according to an embodiment of the present invention, and the method includes the following steps:

Step S1: Measure the output torque T of the vehicle motor and the wheel speed ω. Here, the output torque T can be obtained by measuring the input current of the motor. In the constant current state, the output torque T of the motor is equal to the product of the torque constant and the input current of the motor, and the wheel speed ω can be obtained by measuring the speed of the motor. To

Step S2: Estimate the adhesion moment T _d . Here, the adhesion torque T _d is based on the formula

Estimated, where J is the inertial variable of the vehicle,

Is the derivative of the wheel speed ω. The inertial variable J of the vehicle is related to the parameters of the vehicle. Its value does not change with the environment and time. It can be determined by measurement. Normally, the parameter J is a known quantity. However, for the first use of the vehicle, in step S2 Previously, the step of initializing the inertial variable J of the vehicle needs to be performed to determine the value of the parameter J. The derivation processing formula for wheel speed ω is

Where Δt represents the time difference between the two measurements before and after, and Δω represents the difference of the wheel speed ω (ω(k)-ω(k-1)) between the two measurements. From this, the adhesion torque T _d can be derived.

Preferably, before step S2, it may further include: filtering the wheel speed ω to filter out noise interference during measurement and improve the accuracy of the subsequent derivative calculation results. Further preferably, a low-pass filter can be used to filter the wheel speed ω.

Step S3: Calculate the output torque change value ΔT and the adhesion torque change value ΔT _d . Here, the output torque change value ΔT and the adhesion torque change value ΔT _d respectively represent the difference between the output torque T transmitted by the motor to the wheel and the wheel adhesion torque T _d for two consecutive measurements. The calculation formula is: ΔT=T(k)-T(k-1) and ΔT _d =T _d (k)-T _d (k-1), where T(k) represents the current measured and calculated output torque value, T(k -1) represents the output torque value of the motor during the last measurement calculation, T _d (k) represents the current estimated adhesion torque value, and T _d (k-1) represents the last estimated adhesion torque value. Thus, the output torque change value ΔT and the adhesion torque change value ΔT _d can be calculated.

Step S4: Judging the working state of the vehicle in the traction state according to the output torque change value ΔT and the adhesion torque change value ΔT _d. Specifically, there can be the following two criteria.

The first criterion is: when the output torque change value ΔT>0 and the adhesion torque change value ΔT _d >0, or when the output torque change value ΔT<0 and the adhesion torque change value ΔT _d <0, Or when the output torque change value ΔT=0 and the adhesion torque change value ΔT _d >=0, it is determined that the vehicle in the traction state is in a stable working state; when the output torque change value ΔT>0 and the adhesion torque change value ΔT _d <0, or when the output torque change value ΔT<0 and the adhesion torque change value ΔT _d >0, or when the output torque change value ΔT=0 and the adhesion torque change value ΔT _d <0, it is determined The vehicle in the towing state is in an unstable working state.

The second criterion is: in the case of △T≠0, when

And

When it is determined that the vehicle is in a stable working state;

And

When, it is determined that the vehicle is in an unstable working state;

And

In the case of △T=0, when △T _d <0, it is judged that the vehicle is in an unstable working state; when △T _d >=0, it is judged that the vehicle is in a stable working state;

In short, for the case of △T≠0, when the output torque and the adhesion torque have the same changing trend, that is, both become larger or both become smaller, the vehicle is in a stable working state, otherwise it is in an unstable working state. In the case of ΔT=0, the vehicle is in a special state of motion at this moment, and the output torque of the vehicle does not change, which is relatively rare. At this moment, if ΔT _d > 0, it means that the adhesion moment between the wheels and the ground is increasing, indicating that the vehicle is in a stable working state, or ΔT _d =0, indicating that the adhesion moment between the wheels and the ground is stable, and the vehicle is in a stable state. Working state; on the contrary, it indicates that the vehicle is in an unstable working state.

For the case of ΔT≠0 and ΔT _d =0, since the torque T transmitted by the motor of the vehicle to the wheels is the cause of the change in the adhesion torque between the wheels and the ground, when ΔT≠0, T _d must change, so when ΔT≠0 The state of ΔT _d = 0 is unlikely to occur, so this state does not need to be considered.

The principle of the method for judging the working state of the vehicle in the traction state according to the embodiment of the present invention will be described in detail below.

The driving force of the vehicle forward comes from the friction between the wheels and the ground. The driving force of the power system to the wheels is converted into the driving force of the vehicle and the friction and heat generated by the wheels and the ground. Therefore, the vehicle speed in the traction state is lower than the rotation speed of the wheels (linear wheel speed); in the braking state, the vehicle speed is greater than the rotation speed of the wheels (linear wheel speed). The expression of vehicle slip rate λ is:

λ={(ωr-ν)/max(ωr,ν,ε)}

Among them: ω represents the wheel angular velocity, r represents the wheel radius, ν represents the vehicle speed, and ε is a small constant that prevents the denominator of the formula from being zero.

The method for judging the working state of a vehicle provided in this embodiment is only applicable to a vehicle in a traction state, so

λ={(ωr-ν)/ωr}, where ωr≠0 (1) To

The slip rate λ of a car reflects the interaction relationship between the vehicle tires and the ground, through the change relationship between the slip rate λ and the friction factor μ

It can judge the stability of the vehicle when it is working. Studies have shown that: on different ground (dry ground, watery road and icy surface), there is a regular non-linear relationship between the slip rate λ and the friction coefficient μ of the car. As shown in Figure 2, it is a schematic diagram of the λ-μ relationship when the car is on different roads. It can be seen that in the three road environments, the friction and slip rate of the vehicle have similar changing trends: in the stable zone, The increase in the slip rate of the vehicle is accompanied by the increase in friction. The friction provides adhesion to the vehicle so that the vehicle can work normally; when the vehicle is working in a critical state and in an unstable zone, the friction of the vehicle reaches its maximum value. When the force is not following the increase in the slip rate of the vehicle, the wheels of the vehicle slip.

The correlation between the vehicle slip coefficient λ and the friction coefficient μ can be divided into two areas, one area is a stable area, and the other part is called an unstable area (slip area).

If the slip rate λ and the friction factor μ satisfy the formula

This shows that the vehicle is running in a stable working state, and the friction force of the vehicle changes with the change of the slip rate at this time.

If the slip rate λ and the friction system μ satisfy the formula

It means that the car is running in a critical state, when the friction force of the car reaches the maximum value and no longer follows the change of slip rate.

If the slip rate λ and the friction system μ satisfy the formula

It shows that the car is working in an unstable working state (slip state), and the friction of the wheel at this time decreases with the increase of the slip rate.

The direct causal relationship between the change of wheel friction and the change of slip rate and the stability of the car at work can be achieved through

It is obtained by rigorous analysis and derivation, and the derivation process is shown in formula (2):

Among them: N represents the normal phase pressure of the car wheel against the ground, which is a constant; F _d represents the adhesion (friction force) between the wheel and the ground.

As shown in Figure 3, it is a schematic diagram of the force distribution when the vehicle wheels are working. Through the analysis of the force distribution of the wheel model, it can be seen that the adhesion force between the wheel and the ground when the wheel rotates and the driving force of the wheel driving the vehicle forward are a pair of interaction forces. When the output driving force of the vehicle motor is greater than the maximum friction between the wheel and the ground When the force is applied, the wheels will slip. When there is a slipping state, the rotation speed of the wheel will increase at this time, and the resistance of the wheel is composed of the adhesion force of the wheel and the ground and the inertia force of the wheel rotation. According to the dynamic theory of wheel rotation motion, the torque distribution of the wheel during operation satisfies formula (3): To

which is

Among them: J is the inertia constant of the tire; T is the output torque of the motor; F _d is the adhesion force between the wheel and the ground; T _d is the torque generated by the friction between the wheel and the ground on the wheel, that is, the wheel adhesion moment, due to the force The frictional torque is also the driving torque for driving the wheels forward; the torque produced by the frictional force is subtracted from the output torque of the motor. When the difference is greater than 0, it is the slipping torque of the wheel, that is, the frictional force of the wheel is less than the driving force of the wheel. The wheels slip, and the excess energy is consumed by the slipping heat. Using the product of the inertia force of the wheel and the rate of change of the wheel angular velocity, the wheel slip moment can be calculated.

The dynamic formula of the longitudinal motion of the car is:

MV=(F _d -F _dr )t (4)

Among them: M represents the mass of the car; V represents the vehicle speed; F _dr is the inertial resistance when the wheel rotates, which is a constant.

The formula for calculating the driving force for wheel acceleration is:

F _d ＝μ*N (5)

According to the μ-λ relationship curve in Figure 2, g is used to represent the slope of the curve at a certain operating point of the curve. Assuming that the μ-λ curve shows a linear relationship within a short distance, the value of the slope g of the curve at the operating point i can be Expressed as:

That is, Δμ=g*Δλ (6)

At the working point i, the following equation can be obtained from the slip rate:

This is the small signal linearization formula in control.

From formula (3), we can get:

From formula (4), we can get:

From formulas (5) and (6), we can get: ΔF _d =N*Δμ=N*g*Δλ (10)

From formula (7), we know:

From formulas (1) and (10), we can see:

V _i =(1-λ _i )rω _i ; (12)

Δλ=ΔF _d /g*N; (13)

So the expression of Δω can be converted to:

From formula (8), formula (9) and formula (14), we can know:

After Laplace transform of formula (15), we can get:

Finally, we can get the linear open-loop transfer function of the vehicle stability factor:

K is a static gain parameter, it shows that when the slip rate increases, the motor's driving torque can be reduced. The expression of K is:

The value of the time parameter τ is:

Assuming that near a certain operating point, the torque applied by the motor to the wheels has a step change △T, and its amplitude is ε, then there is:

△T=ε·1(t) (20)

Among them, 1(t) represents a unit step signal.

According to formula (17) and formula (20), and the principle of inverse Laplace transform, we can get:

From formula (21), we can get: To

According to formula (3), the calculation formula of _{T d value is:}

From formula (18), (19), (22) and formula (23), we can know:

when

When the value of is less than 0, then 1-e ^-t/τ <0, so there must be a time constant τ less than 0; at this time, the parameter g must also be less than 0, and finally we can deduce:

It can be seen that the working state of the vehicle is an unstable working state.

The same goes for:

when

When the value of is greater than 0, then 1-e ^-t/τ <0, so there must be a time constant τ greater than 0; at this time, the parameter g must also be greater than 0, and finally we can deduce:

It can be seen that the working state of the vehicle is a stable working state.

Therefore, from the above derivation, it can be concluded that by

The value can get the working status of the vehicle.

Analyze the situation when ΔT=0: At this time, the above division operation cannot be used directly, so this special case needs to be considered separately. When ΔT=0, it means that the motor outputs a constant torque, that is, the amount of change is zero. At this time, in a transient state, when in a stable region, there will be ΔT _d > 0, and there should be ΔT _d =0. In addition, when the road suddenly changes from a high-adhesion road to a low-adhesion road, even if the motor output torque remains unchanged, that is, ΔT=0, we will observe a decrease in adhesion, that is, ΔT _d <0, so it is unstable In the area, ΔT _d <0. Therefore, based on the above judgment, the criterion in this special situation is given:

If ΔT=0 and ΔT _d <0, the vehicle is in an unstable working state;

If ΔT=0 and ΔT _d >=0, the vehicle is in a stable working state.

In actual detection, the detection of the output torque and wheel adhesion torque transmitted by the motor of the car is discrete, so ΔT _d and ΔT represent the output torque T transmitted by the motor to the wheel and the wheel adhesion torque T _d Check the difference of the calculated value twice in succession. The calculation formula is: ΔT _d =T _d (k)-T _d (k-1) and ΔT=T(k)-T(k-1). Therefore, in practical applications, the description of the method for judging vehicle working stability is as follows:

(1). When ΔT _d >0 and ΔT>0, then

Assuming dT(s)>0, so dT _d (s)>0, that is, the adhesion of the wheel to the ground increases with the increase of the motor output torque, indicating that the vehicle is in a stable working state.

(2). When ΔT _d <0 and ΔT<0, then

The adhesion of the wheels to the ground decreases as the output torque of the motor decreases, indicating that the vehicle is in a stable working state.

(3). When ΔT _d <0 and ΔT>0, then

The adhesion of the wheels to the ground decreases with the increase of the output torque of the vehicle motor, indicating that the wheels have slipped and the vehicle is in an unstable working state.

(4). When ΔT _d >0 and ΔT<0, then

That is, the adhesion of the wheels to the ground increases as the output torque of the motor decreases, indicating that the vehicle is in an unstable working area and the working state of the vehicle moves to a stable area.

(5). When ΔT=0, the vehicle is in a special state of motion at this moment, and the output torque of the vehicle does not change. This state is relatively rare. If ΔT _d >=0 at this moment, it means that the adhesion moment between the wheels and the ground is increasing or balancing, which means that the vehicle is in a stable working state; otherwise, it means that the vehicle is in an unstable working state.

Therefore, it is possible to judge the working state of the vehicle under the traction state by the change value of the output torque of the vehicle motor and the change value of the adhesion torque of the wheels, without knowing the vehicle chassis speed and slip rate value, the judgment process is simple and reliable, and the method The output parameters can be used in the vehicle slip control process, this method is very suitable for the practical application of vehicle control. In addition, fewer sensors are required, implementation costs are low, and reliability is high.

Example 2

Fig. 4 shows a flowchart of a method for judging the working state of a vehicle in a traction state according to another embodiment of the present invention, and the method includes the following steps:

Step S21: Initialize the inertia constant J of the vehicle.

Step S22: Measure the output torque T of the vehicle motor and the wheel speed ω.

Step S23: filtering the wheel speed ω, preferably a low-pass filter may be used to filter the wheel speed ω.

Step S24: Estimate the adhesion moment T _d . According to the formula

To estimate the adhesion moment T _d , where

Is the derivative of the wheel speed ω.

Step S25: Calculate the output torque change value ΔT and the adhesion torque change value ΔT _d .

Step S26: Judging the working state of the vehicle in the traction state according to the output torque change value ΔT and the adhesion torque change value ΔT _d.

Step S27: Determine in real time whether to implement limiting control on the output torque T according to the determined operating state of the vehicle, which specifically includes: when the vehicle is in an unstable operating state, deciding to implement limiting control on the output torque T of the vehicle motor , To make the vehicle return to a stable working state; when the vehicle is in a stable working state, it is decided not to implement limiting control on the output torque T of the vehicle motor. The output torque T is controlled by limiting, that is, the value of the output torque T is limited to a small value to reduce the wheel speed ω, so that the vehicle slowly stabilizes and no longer slips, and finally runs stably at a low speed.

Repeat steps S22 to S27, where in step S27, when it is found that the vehicle in the traction state has changed from a stable working state to an unsteady working state, the output torque is controlled by limiting; in the next detection, if the vehicle is When it is still in an unstable working state, the output torque will continue to be controlled by limiting. If the vehicle has been converted from an unstable working state to a stable working state, the limiting control on the output torque will be cancelled so that the driver can Take over the control, otherwise, the vehicle will always maintain the limit value of the previous attached road to limit the output torque of the motor. Even after the road is converted to a high adhesion road, the limit control of the output torque cannot be cancelled, resulting in The vehicle cannot use the adhesion of high-adhesion roads to achieve normal acceleration of the vehicle. This embodiment provides a method for judging the working state of a vehicle in a traction state. Based on the physical and mechanical theory of the vehicle slipping process, it only needs to measure the output torque of the vehicle motor to the wheels and wheel speed information to determine the state of the vehicle in the traction state. The vehicle working state does not need to know the vehicle chassis speed and slip rate values, the determination process is simple and reliable, and the output parameters of the method can be used in the vehicle slip control process. This method is very suitable for the practical application of vehicle control. In addition, fewer sensors are required, implementation costs are low, and reliability is high. The invention is also suitable for detecting the slip state of four-wheel drive vehicles driven by motors and various robots and machine exoskeletons driven by motors.

Example 3

As shown in Figure 5, the present invention also provides a system for judging the working state of a vehicle in a towing state, including:

The measurement module 32 is used to measure the output torque T and wheel speed ω of the vehicle motor;

The estimation module 34 is used to estimate the adhesion moment T _d ;

The calculation module 35 is used to calculate the output torque change value ΔT and the adhesion torque change value ΔT _d ;

The determination module 36 is configured to determine the working state of the vehicle in the traction state according to the output torque change value ΔT and the adhesion torque change value ΔT _d.

This embodiment provides a system for judging the working state of the vehicle in the traction state. It only needs to measure the output torque of the vehicle motor to the wheels and wheel speed information to judge the working state of the vehicle in the traction state, without knowing the vehicle. To The determination process of the chassis speed and slip rate value is simple and reliable, and the output parameters of this method can be used in the vehicle slip control process, which is very suitable for the practical application of vehicle control.

In addition to the aforementioned modules, the system may also include: an initialization module 31 for obtaining the inertia constant J of the vehicle. The initialization module 31 is usually activated only when the vehicle is used for the first time to determine the value of the parameter J. For subsequent use of the vehicle, since the inertia constant J is a known value, the initialization module 31 does not need to be activated.

Preferably, the system may further include: a filtering module 33 for filtering the measured wheel speed ω to filter out noise interference during measurement and improve the accuracy of subsequent derivative calculation results. Further preferably, a low-pass filter can be used to filter the wheel speed ω.

Optimally, the system may further include: an amplitude limiting module 37, which is used to implement amplitude limiting control on the output torque of the vehicle motor when the vehicle is in an unstable working state. That is, when the vehicle is in an unstable working state, the output torque T is limited to a small value, and the wheel speed is reduced, so that the vehicle gradually gets rid of the slipping state and is in a stable working state of low-speed driving.

This embodiment provides a system for judging the working state of a vehicle in a traction state. It only needs to measure the output torque of the vehicle motor to the wheels and wheel speed information to judge the working state of the vehicle in the traction state without knowing the vehicle chassis. The speed and slip rate value, the determination process is simple and reliable, and the output parameters of this method can be used in the vehicle slip control process, this method is very suitable for the practical application of vehicle control. In addition, fewer sensors are required, implementation costs are low, and reliability is high.

Obviously, the above-mentioned embodiments are merely examples for clear description, and are not intended to limit the implementation manners. For those of ordinary skill in the art, other changes or modifications in different forms can be made on the basis of the above description. It is unnecessary and impossible to list all the implementation methods here. The obvious changes or changes derived from this are still within the protection scope created by the present invention. To

Claims

A method for judging the working state of a vehicle in a traction state, characterized in that it comprises:

Measure the output torque T of the vehicle motor and the wheel speed ω;

Estimate the adhesion moment T d ;

Calculate the output torque change value ΔT and the adhesion torque change value ΔT d ;

According to the output torque change value ΔT and the adhesion torque change value ΔT d , the working state of the vehicle in the traction state is judged.
The method according to claim 1, characterized in that, before the step of measuring the output torque T of the vehicle motor and the wheel rotation speed ω, the method further comprises:

The inertial constant J of the vehicle is initialized, and the inertial constant J is related to the parameters of the vehicle.
The method according to claim 1 or 2, characterized in that, before the step of estimating the adhesion moment Td, the method further comprises:

Filter processing is performed on the wheel rotation speed ω.
The method according to any one of claims 1-3, wherein the output torque T is obtained by measuring the input current of the motor, and in a constant current state, the output torque T is equal to the torque constant and The product of motor input current.
The method according to any one of claims 1-4, wherein the adhesion torque T d is based on the formula
Estimated, where
Is the derivative of the wheel speed ω.
The method according to any one of claims 1-5, wherein the judging the working state of the vehicle in the traction state according to the output torque change value ΔT and the adhesion torque change value ΔT d includes :

When the output torque change value ΔT>0 and the adhesion torque change value ΔT d >0, or when the output torque change value ΔT<0 and the adhesion torque change value ΔT d <0 , Or when the output torque change value ΔT=0 and the adhesion torque change value ΔT d >=0, it is determined that the vehicle in the traction state is in a stable working state;

When the output torque change value ΔT>0 and the adhesion torque change value ΔT d <0, or when the output torque change value ΔT<0 and the adhesion torque change value ΔT d >0 , Or when the output torque change value ΔT=0 and the adhesion torque change value ΔT d <0, it is determined that the vehicle in the traction state is in an unstable working state.
The method according to any one of claims 1 to 6, wherein the judging the working state of the vehicle in the traction state according to the output torque change value ΔT and the adhesion torque change value ΔT d includes :

In the case of △T≠0,

when
And
When it is determined that the vehicle is in a critical transition state that is about to transition from a stable working state to an unsteady working state;

when
And
When, determine that the vehicle is in a stable working state;

when
And
When, determine that the vehicle is in an unstable working state;

when
And
When it is time, it is determined that the vehicle is at the critical transition point from the unstable working state to the stable working state;

In the case of △T=0,

When △T d <0, it is determined that the vehicle is in an unstable working state;

When △T d >=0, it is determined that the vehicle is in a stable working state;

Among them, ΔT(k) is the current calculated output torque change value, ΔT(k-1) is the last calculated output torque change value, ΔT d (k) is the current calculated adhesion torque change value , ΔT d (k-1) is the change value of the adhesion torque calculated last time.
The method according to any one of claims 1-7, wherein the step of judging the working state of the vehicle in the traction state according to the output torque change value ΔT and the adhesion torque change value ΔT d After that, it also includes: determining in real time whether to implement limiting control on the output torque T according to the determined vehicle working state.
The method according to claim 8, wherein the real-time determination of whether to implement limiting control on the output torque T according to the determined vehicle operating state comprises:

When it is determined that the vehicle is in an unsteady working state, limit the amplitude control of the output torque T;

When it is determined that the vehicle is in a stable working state, the output torque T is not subject to limit control.
A system for judging the working state of a vehicle in a traction state, which is characterized in that it includes:

A measurement module for measuring the output torque T and the wheel speed ω of the vehicle motor; To

An estimation module for estimating the adhesion moment T d ;

A calculation module for calculating the output torque change value ΔT and the adhesion torque change value ΔT d ;

The determination module is used to determine the working state of the vehicle in the traction state according to the output torque change value ΔT and the adhesion torque change value ΔT d.
The system of claim 10, further comprising:

The initialization module is used to obtain the inertial constant J of the vehicle; and/or

A filtering module for filtering the measured wheel speed ω; and/or

The limiter module is used to limit the output torque T when the vehicle in the traction state is in an unstable working state. To