CN110361967A - The construction method of sliding mode observer - Google Patents

The construction method of sliding mode observer Download PDF

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CN110361967A
CN110361967A CN201910420812.4A CN201910420812A CN110361967A CN 110361967 A CN110361967 A CN 110361967A CN 201910420812 A CN201910420812 A CN 201910420812A CN 110361967 A CN110361967 A CN 110361967A
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sliding mode
mode observer
sliding
state
state variable
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CN110361967B (en
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徐岩
刘辉
韩立金
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Beijing University of Technology
Beijing Institute of Technology BIT
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    • GPHYSICS
    • G05CONTROLLING; REGULATING
    • G05BCONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
    • G05B13/00Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion
    • G05B13/02Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric
    • G05B13/04Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric involving the use of models or simulators
    • G05B13/042Adaptive control systems, i.e. systems automatically adjusting themselves to have a performance which is optimum according to some preassigned criterion electric involving the use of models or simulators in which a parameter or coefficient is automatically adjusted to optimise the performance

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Abstract

The invention discloses a kind of construction methods of sliding mode observer, include the following steps, step 1, vehicle drive shaft is reduced to the system being made of spring and damping, the state space equation of sliding mode observer is established to the system, step 2, the output estimation error feedback term in utilization index Reaching Law and exponential function building sliding mode observer state space equation;Step 3, based on output estimation error feedback term building sliding mode observer equation and structure;The sliding mode observer that the present invention constructs can the torque estimation result in time to vehicle correct so that drive system torque estimated value approach actual value, alleviate chattering phenomenon, reduce phase delay, observed result is more accurate.

Description

The construction method of sliding mode observer
Technical field
The invention belongs to sliding formwork control technical fields, more particularly to a kind of construction method of sliding mode observer.
Background technique
When calculating drive shaft torque using line integral method in the prior art, wheel speed sensor, motor rotation will receive Become error influence, signals of rotational speed sensor noise, external interference etc. also due to integral action in torque estimation result by It gradually adds up, estimated value and actual value is finally made to generate large error, when Assumption torque initial value and actual value have deviation, evaluated error May be very big, application difficult in practice.
Luenberger observer has preferable observation effect, but vehicle for the system for being mainly shown as linear characteristic It is typical non-thread since there are the non-linear factors such as Coulomb damping, air drag and backlash in power drive system Property system, while more simplification has been carried out in transmission system modeling process, there is likely to be unknown disturbances in real system, Zero can not be leveled off to using the evaluated error that Systems with Linear Observation device exports drive system, and the system mode of estimation is difficult to converge to System virtual condition.
Therefore, it is necessary to be fed back using practical can measure, torque estimation result is corrected, enable estimated value with With actual value, and the influence of external interference is resisted, that is, needs to design a sliding mode observer and driving shaft torque is observed.
Summary of the invention
The purpose of the present invention is to provide a kind of construction methods of sliding mode observer, and building process is simple, utilization index letter Number realizes that under nonlinear state, the torque estimated value of drive system and the deviation of actual value reduce, and eliminates drive system shape State approaches buffeting when sliding-mode surface, reduces phase delay, so that the sliding mode observer observed result accuracy of building is higher.
The technical scheme adopted by the invention is that the construction method of sliding mode observer specifically includes the following steps:
Step 1, vehicle drive shaft is reduced to the system being made of spring and damping, the state for establishing sliding mode observer is empty Between equation, the general type of sliding mode observer such as formula (1):
If x is state variable,Y is output quantity,For state estimation error,It is defeated Evaluated error out, v are the feedback term of output estimation error, GnFor gain matrix,
For motor speed,To export revolving speed, TsFor output shaft torque, CtFor retarder damping, CvFor wheel damping, CsFor Drive shaft damping, JvIt is equivalent to the sum of the equivalent inertia of wheel and wheel inertia, J for car bodypFor the rotor inertia of motor B, irFor Final driver ratio, ksFor drive shaft rigidity, i is final driver ratio, TpFor driving torque, TvFor vehicle load torque;
Step 2, using exponentially approaching rule and exponential function, the output estimation error feedback term of sliding mode observer is set;
Step 3, sliding mode observer equation and structure are established.
Further, in step 2 output estimation error feedback term are as follows:
V=- ε sigmoid (s)-qs ε > 0, q > 0
Wherein ε is sliding formwork gain, and q is exponential approach gain, and s is drive system state at a distance from sliding-mode surface,It is any Positive integer.
Further, the equation for the sliding mode observer that step 3 is established are as follows:
WhereinIt is state variable x1Measured value,It is state variable x2Measured value,For state variable x3Measurement Value, s1Be state variable be x1When drive system state at a distance from sliding-mode surface, s2Be state variable be x2When drive system state At a distance from sliding-mode surface, q1It is state variable x1Exponential approach gain, q2It is state variable x2Exponential approach gain, ε1It is shape State variable x1Sliding formwork gain, ε2It is state variable x2Sliding formwork gain, L1、L2For feedback gain;
The state error of sliding mode observerEquation are as follows:
Further, sliding mode observer sliding formwork gain selection should meet the following conditions:
Wherein e3It is state variable x3State estimation error.
The beneficial effects of the present invention are: the process that the present invention constructs sliding mode observer is simple, index letter is used in building Number eliminates the buffeting generated when drive system state approach sliding-mode surface, when so that the sliding mode observer of building being used to detect, detection Order of accuarcy is high.
Detailed description of the invention
In order to more clearly explain the embodiment of the invention or the technical proposal in the existing technology, to embodiment or will show below There is attached drawing needed in technical description to be briefly described, it should be apparent that, the accompanying drawings in the following description is only this Some embodiments of invention for those of ordinary skill in the art without creative efforts, can be with It obtains other drawings based on these drawings.
Fig. 1 is dynamical system simplified model figure.
Fig. 2 is torque sliding mode observer structure chart.
Fig. 3 is that the present invention cuts down result figure to the torsional oscillation of linear model.
Fig. 4 is that the present invention cuts down result figure to the torsional oscillation of nonlinear model.
Specific embodiment
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete Site preparation description, it is clear that described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.It is based on Embodiment in the present invention, it is obtained by those of ordinary skill in the art without making creative efforts every other Embodiment shall fall within the protection scope of the present invention.
The construction method of sliding mode observer, specifically includes the following steps:
Step 1: vehicle drive shaft being reduced to the system being made of spring and damping, structure is as shown in Figure 1, establish sliding formwork The state space equation of observer, shown in the general type of sliding mode observer such as formula (1):
X is state variable in formula (1),Y is output quantity, ifFor state estimation error,For output estimation error, v is the feedback term of output estimation error, GnFor gain matrix,
WhereinFor motor speed,To export revolving speed, TsFor output shaft torque, CtFor retarder damping, CvFor wheel resistance Buddhist nun, CsFor drive shaft damping, JvIt is equivalent to the sum of the equivalent inertia of wheel and wheel inertia, J for car bodypIt is used for the rotor of motor B Amount, irFor final driver ratio, ksFor drive shaft rigidity, i is final driver ratio, TpFor driving torque, TvIt is negative for vehicle Set torque;
Step 2: using exponentially approaching rule and exponential function, the output estimation error feedback term v of sliding mode observer is set;
Feedback term of the utilization index Reaching Law as output estimation error, so that torque estimated value rapidly converges to reality Value, shown in exponentially approaching rule such as formula (2):
V=- ε sgn (s)-qs ε > 0, q > 0 (2)
Wherein ε is sliding formwork gain, and q is exponential approach gain, and s is drive system state at a distance from sliding-mode surface;Index becomes Nearly rule converges to any point in state space on sliding-mode surface with exponential form, and convergence rate increases with exponential approach gain q And accelerate, but the excessive state variable that will lead to of exponential approach gain has biggish chatter on sliding-mode surface;Drive system state Far from sliding-mode surface, i.e., when s absolute value is larger, drive system state can fast approach sliding-mode surface, so that s=0;Drive system state Close to sliding-mode surface, i.e., when s absolute value is smaller, the speed of drive system state approach sliding-mode surface is gradually reduced, and switches item-ε sgn (s) it can guarantee that drive system reaches sliding-mode surface in finite time;
The symbolization function sgn (s) in the feedback term of output estimation error, so that drive system state reaches sliding formwork With certain speed when face, sliding-mode surface can be crossed under effect of inertia, then control action is reversed, subtracts drive system state Speed reversely approaches sliding-mode surface, repeatedly, causes to buffet, and the present invention eliminates drive system using exponential function sigmoid (s) State approaches the buffeting generated when sliding-mode surface, shown in the calculating of exponential function such as formula (3):
WhereinFor any positive integer;
With the sgn (s) in formula (3) replacement formula (2), the feedback term such as formula (4) of output error in sliding mode observer It is shown:
V=- ε sigmoid (s)-qs ε > 0, q > 0 (4)
Step 3, sliding mode observer equation and structure are established;
According to the state space equation of sliding mode observer, sliding-mode surface function S is set are as follows:
Gain matrix GnForm beWherein L ∈ R1 ×2, I is unit matrix, and L is the coefficient matrix of 1*2, and R indicates that L is real number matrix;
Then shown in the expression formula of sliding mode observer such as formula (5):
Wherein JpFor the rotor inertia of motor B, JvIt is equivalent to the sum of the equivalent inertia of wheel and wheel inertia, T for car bodyv For vehicle load torque, CtFor retarder damping, CvFor wheel damping, CsFor drive shaft damping, ksFor drive shaft rigidity, TPIt is Force system driving torque,It is state variable x1Measured value,It is state variable x2Measured value,For state variable x3's Measured value, s1Be state variable be x1When drive system state at a distance from sliding-mode surface, s2Be state variable be x2When drive system State is at a distance from sliding-mode surface, q1It is state variable x1Exponential approach gain, q2It is state variable x2Exponential approach gain, ε1 It is state variable x1Sliding formwork gain, ε2It is state variable x2Sliding formwork gain, L1、L2For feedback gain;
The error of sliding mode observerEquation are as follows:
Shown in the error such as formula (7) for the state variable and virtual condition that sliding mode observer measures:
e1It is state variable x1State estimation error, e2It is state variable x2State estimation error, e3It is state variable x3State estimation error;
Utilize the stability of Lyapunov Theory of Stability verifying sliding mode observer, the Lyapunov function of sliding mode observer As shown in formula (8):
Wherein S is the matrix that drive system state is formed with sliding-mode surface distance s;
It substitutes into formula (7) and can obtain to formula (8) derivation, and by derivation result:
By formula (9) it is found that being the stability for guaranteeing sliding mode observer, the sliding formwork gain of sliding mode observer is answered when choosing Meet following condition:
1)e1> 0 and e2> 0,
2)e1> 0 and e2< 0,
3)e1< 0 and e2> 0,
4)e1< 0 and e2< 0,
JPFor the rotor inertia of motor B, ε is sliding formwork gain, and i is transmission ratio, and e is state estimation error;
Condition is chosen to the synovial membrane gain of sliding mode observer and carries out computational short cut, is derived as guaranteeing the progressive of sliding mode observer The sliding formwork gain of stability, sliding mode observer should meet following condition:
Utilization index Reaching Law and exponential function in the sliding mode observer that the present invention constructs construct the anti-of output estimation error Item is presented, so that drive system state can slow down in time when close to sliding-mode surface, alleviate drive system trembling near sliding-mode surface Phenomenon of shaking reduces phase delay, so that the observed result of sliding mode observer so that the speed of estimated value approach actual value is faster It is more accurate.
Embodiment
Transmission system simplified model is built in Matlab/Simulink, and the delay of power source is considered in modeling process Characteristic and power source, the frictional resistance of actuated element etc. imitate sliding mode observer observation effect based on this simplified model True verifying, as a result as shown in Figure 3 and Figure 4, from the figure 3, it may be seen that sliding mode observer has good observing capacity in a linear system, The observed result of sliding mode observer can be good at tracking the virtual condition of vehicle, reach good observation effect, sliding formwork in Fig. 4 Observer is still able to maintain preferable observed result in nonlinear model, exists to stablize between observed result and actual torque and miss Difference, sliding mode observer is when being observed driving shaft torque, directly by the torque command of power drive system as system Torque output is inputted in sliding mode observer and is calculated, due to the presence of frictional resistance moment, so that the reality output of power source turns There are steady state difference value between square and torque command, being reflected in is stable state observation error on sliding mode observer observed result, still Error can guarantee within 5% substantially.
Each embodiment in this specification is all made of relevant mode and describes, same and similar portion between each embodiment Dividing may refer to each other, and each embodiment focuses on the differences from other embodiments.Especially for system reality For applying example, since it is substantially similar to the method embodiment, so being described relatively simple, related place is referring to embodiment of the method Part explanation.
The foregoing is merely illustrative of the preferred embodiments of the present invention, is not intended to limit the scope of the present invention.It is all Any modification, equivalent replacement, improvement and so within the spirit and principles in the present invention, are all contained in protection scope of the present invention It is interior.

Claims (4)

1. the construction method of sliding mode observer, which is characterized in that specifically includes the following steps:
Step 1, vehicle drive shaft is reduced to the system being made of spring and damping, establishes the state space side of sliding mode observer Journey, the general type of sliding mode observer such as formula (1):
If x is state variable,Y is output quantity,For state estimation error,For output estimation Error, v are the feedback term of output estimation error, GnFor gain matrix,
For Motor speed,To export revolving speed, TsFor output shaft torque, CtFor retarder damping, CvFor wheel damping, CsFor drive shaft resistance Buddhist nun, JvIt is equivalent to the sum of the equivalent inertia of wheel and wheel inertia, J for car bodypFor the rotor inertia of motor B, irFor main reducing gear Transmission ratio, ksFor drive shaft rigidity, i is final driver ratio, TpFor driving torque, TvFor vehicle load torque;
Step 2, using exponentially approaching rule and exponential function, the output estimation error feedback term of sliding mode observer is set;
Step 3, sliding mode observer equation and structure are established.
2. the construction method of sliding mode observer according to claim 1, which is characterized in that output estimation in the step 2 The feedback term of error are as follows:
V=- ε sigmoid (s)-qs ε > 0, q > 0
Wherein ε is sliding formwork gain, and q is exponential approach gain, and s is drive system state at a distance from sliding-mode surface,It is arbitrarily just whole Number.
3. the construction method of sliding mode observer according to claim 1, which is characterized in that the sliding formwork that the step 3 is established The equation of observer are as follows:
WhereinIt is state variable x1Measured value,It is state variable x2Measured value,For state variable x3Measured value, s1 Be state variable be x1When drive system state at a distance from sliding-mode surface, s2Be state variable be x2When drive system state and cunning The distance of die face, q1It is state variable x1Exponential approach gain, q2It is state variable x2Exponential approach gain, ε1It is that state becomes Measure x1Sliding formwork gain, ε2It is state variable x2Sliding formwork gain, L1、L2For feedback gain;
The state error of sliding mode observerEquation are as follows:
4. the construction method of sliding mode observer according to claim 1, which is characterized in that the sliding mode observer sliding formwork increases Benefit, which is chosen, to meet the following conditions:
Wherein e3It is state variable x3State estimation error.
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CN113824114A (en) * 2021-11-22 2021-12-21 广东电网有限责任公司惠州供电局 Power distribution network state estimation method, device, system and medium based on sliding mode observation
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Publication number Priority date Publication date Assignee Title
CN112526880A (en) * 2020-11-25 2021-03-19 哈尔滨工业大学 Real-time estimation method for road surface height in vehicle driving process
CN112526880B (en) * 2020-11-25 2022-06-10 哈尔滨工业大学 Real-time estimation method for road surface height in vehicle driving process
CN113824114A (en) * 2021-11-22 2021-12-21 广东电网有限责任公司惠州供电局 Power distribution network state estimation method, device, system and medium based on sliding mode observation
CN113824114B (en) * 2021-11-22 2022-03-18 广东电网有限责任公司惠州供电局 Power distribution network state estimation method, device, system and medium based on sliding mode observation
CN114785216A (en) * 2022-05-12 2022-07-22 合肥工业大学 Design method of self-adaptive gain sliding-mode observer
CN114785216B (en) * 2022-05-12 2024-03-26 合肥工业大学 Design method of self-adaptive gain sliding mode observer

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