CN110435636A - It is a kind of to consider that cargo goes up and down the Optimal Control Strategy influenced on fork truck lateral stability - Google Patents

It is a kind of to consider that cargo goes up and down the Optimal Control Strategy influenced on fork truck lateral stability Download PDF

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CN110435636A
CN110435636A CN201910755348.4A CN201910755348A CN110435636A CN 110435636 A CN110435636 A CN 110435636A CN 201910755348 A CN201910755348 A CN 201910755348A CN 110435636 A CN110435636 A CN 110435636A
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fork truck
wheel
formula
cargo
angle
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CN110435636B (en
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肖本贤
张之路
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Hefei University of Technology
Hefei Polytechnic University
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Hefei Polytechnic University
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W10/00—Conjoint control of vehicle sub-units of different type or different function
    • B60W10/18—Conjoint control of vehicle sub-units of different type or different function including control of braking systems
    • B60W10/184—Conjoint control of vehicle sub-units of different type or different function including control of braking systems with wheel brakes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units
    • B60W30/02—Control of vehicle driving stability
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W40/00—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models
    • B60W40/10—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models related to vehicle motion
    • B60W40/112—Roll movement
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W40/00—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models
    • B60W40/12—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models related to parameters of the vehicle itself, e.g. tyre models
    • B60W40/13—Load or weight
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W40/00—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models
    • B60W40/12—Estimation or calculation of non-directly measurable driving parameters for road vehicle drive control systems not related to the control of a particular sub unit, e.g. by using mathematical models related to parameters of the vehicle itself, e.g. tyre models
    • B60W40/13—Load or weight
    • B60W2040/1315—Location of the centre of gravity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2530/00—Input parameters relating to vehicle conditions or values, not covered by groups B60W2510/00 or B60W2520/00
    • B60W2530/10—Weight
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
    • B60W2710/00—Output or target parameters relating to a particular sub-units
    • B60W2710/18—Braking system

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  • Engineering & Computer Science (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Automation & Control Theory (AREA)
  • Physics & Mathematics (AREA)
  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Forklifts And Lifting Vehicles (AREA)
  • Control Of Driving Devices And Active Controlling Of Vehicle (AREA)

Abstract

The present invention relates to a kind of consideration cargos to go up and down the Optimal Control Strategy influenced on fork truck lateral stability, include: to establish the auto model comprising goods weight and cargo lifting speed, determines ideal yaw velocity and ideal side slip angle under fork truck current running state；Detection obtains practical yaw velocity and practical side slip angle under fork truck current running state；It calculates and obtains rear-wheel corner and additional yaw moment；According to the rear-wheel corner and additional yaw moment, and jointly controls tactful, braked wheel selection rule with differential braking according to four-wheel steering and fork truck is jointly controlled.The present invention establishes a kind of new auto model comprising goods weight and cargo lifting speed, which considers influence of the cargo lifting to fork truck lateral stability；A kind of lateral stability controller of simplification particle swarm algorithm based on additional black hole mechanism is devised, which has the advantages that follow ideal performance index real-time, quickly.

Description

It is a kind of to consider that cargo goes up and down the Optimal Control Strategy influenced on fork truck lateral stability
Technical field
The present invention relates to the lateral stability control technology field of fork truck, the especially lifting of consideration cargo are laterally steady to fork truck The Optimal Control Strategy of qualitative effect.
Background technique
With the development of material flow industry, important equipment of the fork truck as transported material, application field is more and more, development Prospect is increasing.Different from conventional trucks such as automobiles, fork truck is since there are cargo liftings to have its particularity, to its stability Assessment needs to consider that cargo lifting causes fork truck synthesis gravity center shift to shadow caused by lateral stability under fork truck load condition It rings.
The lateral stability control of fork truck mainly makes yaw velocity and matter by the methods of four-wheel steering, differential braking Heart side drift angle reaches ideal performance indicator, and current truck stability control method focuses primarily upon under the general operating condition of fork truck Lateral stability control does not consider that particularity, that is, cargo lifting of fork truck causes fork truck synthesis gravity center shift to lateral stability Caused influence does not account for the special operation condition of the fork truck dynamic change of cargo lifting in the process of moving yet.And fork truck is herein Cargo rise and fall will lead to stability reduction under special operation condition, and truck stability mistake can even be occurred by influencing fork truck working efficiency The danger that fork truck caused by weighing topples.
Summary of the invention
The purpose of the present invention is to provide one kind to be capable of fast tracking ideal performance index under special operation condition, solve fork The considerations of cargo goes up and down the problem of caused lateral stability deficiency under vehicle turning condition, improves fork truck working efficiency cargo liter The Optimal Control Strategy influenced on fork truck lateral stability drops.
To achieve the above object, the invention adopts the following technical scheme: a kind of consideration cargo lifting is laterally steady to fork truck The Optimal Control Strategy of qualitative effect, the strategy the following steps are included:
(1) auto model comprising goods weight and cargo lifting speed is established, determines that fork truck is worked as according to the auto model Ideal yaw velocity ω under preceding driving statusdWith ideal side slip angle βd；
(2) detection obtains the practical yaw velocity ω under fork truck current running staterealWith practical side slip angle βreal, then ideal yaw velocity ωdWith practical yaw velocity ωrealActual difference Δ ω, and ideal side slip angle βdWith practical side slip angle βrealActual difference Δ β be respectively as follows: Δ ω=ωd-ωreal, Δ β=βd-βreal；
(3) according to the actual difference Δ ω and actual difference Δ β, using the simplification particle swarm algorithm of additional black hole mechanism It calculates and obtains rear-wheel corner δrWith additional yaw moment MBS；
(4) according to the rear-wheel corner δrWith additional yaw moment MBS, and combine control with differential braking according to four-wheel steering System strategy, braked wheel selection rule jointly control fork truck.
In the step (1), establish the auto model comprising goods weight and cargo lifting speed as follows into Row:
Fork truck differential equation of motion are as follows:
In formula, FyFor side force of tire, m is fork truck quality, vcFor side velocity, u is forward speed, and γ is around z-axis sideway Angular speed, MzFor tyre moment, IzFor around z-axis rotary inertia；Z-axis is the z-axis of cartesian coordinate system；
It is in a linear relationship between side force of tire and side drift angle under low speed, small angle tower vehicle condition, therefore, above formula variation are as follows:
In formula, FfFor front tyre lateral force, FrFor rear tyre lateral force, kfFor front-wheel cornering stiffness, krFor rear wheel-side Inclined rigidity, βfFor front-wheel side drift angle, βrFor rear-wheel side drift angle, lfFor the distance of fork truck mass center to front axle, lrIt is fork truck mass center to rear The distance of axis；The low speed refers to 0 to 15km/h, and the small angle tower refers to front wheel angle 0 to 0.5rad；
The cornering stiffness and side drift angle of front and back wheel determine the size of front and back tire action force:
In formula, δfFor front wheel angle, δrFor rear-wheel corner；β is side slip angle；
Formula (3) are substituted into formula (2), abbreviation is at side slip angle and yaw velocity expression formula are as follows:
Different from conventional forklift model, consider that fork truck synthesizes gravity center shift under cargo jacking conditions, above-mentioned fork truck mass center is extremely The distance l of front axlefAre as follows:
Wherein, lf0Distance of the center of gravity away from front axle centre line under description of the goods is not added for fork truck；y0For cargo under initial situation Horizontal distance of the center of gravity away from forklift front bridge center line, t are the cargo rise time, and α is fork truck back rake angle；Q is goods weight, and v is The cargo rate of climb；
Gravity center shift formula, that is, formula (5) is synthesized in conjunction with fork truck, obtains considering that fork truck includes goods weight and cargo lifting speed The auto model of degree:
In the step (1), the ideal yaw velocity ωdWith ideal side slip angle βdIt obtains as follows:
By ideal side slip angle βdIt is set as 0, it may be assumed that βd=0；
Ideal yaw velocity ωdAcquisition pattern it is as follows:
Forward speed u, front wheel angle δ of the fork truck under current running state are obtained using sensor measurementf, cargo rise Speed v and goods weight q；
The ideal yaw velocity ω for obtaining fork truck is calculated by formula (7)d:
Wherein, GrIt is front-wheel steer fork truck yaw velocity to the steady-state gain of front wheel steering angle,K is The truck stability factor,μ is tire and pavement maximum attachment coefficient, kfFor front-wheel cornering stiffness, krFor Rear-wheel cornering stiffness, lfFor the distance of fork truck mass center to front axle, lrFor the distance of fork truck mass center to rear axle, g is acceleration of gravity, m For fork truck quality, L=lf+lr。
Rear-wheel corner δ is obtained in the step (3)rWith additional yaw moment MBSCalculation method it is specific as follows:
(3a) generates 30 population individual α at randomi, each individual is about rear-wheel corner δrWith additional yaw moment MBS Bivector, using them as initial population Q1, i=1,2...30；
(3b) initializes population position, speed, calculates each particle fitness according to particle fitness calculation formula (8) Value；
minf(xi)=K1|β-βd|+K2|γ-γd| (8)
In formula, β and γ are wherein about rear-wheel corner δrWith additional yaw moment MBSFunction, specially each particle Corresponding yaw velocity and side slip angle value, βdFor ideal yaw velocity, γdFor ideal side slip angle, K1,K2For Normalization factor is chosen for respectivelyGlobal optimum's particle is to calculate resulting value most granule by formula (8) Son is set as Gbest；
(3c) updates population position to the 80% of maximum evolutionary generation using particle swarm algorithm is simplified, and simplifies population and calculates It is as follows that method updates particle position formula:
In formula, t indicates current iteration number, and P is particle current location, and V is the speed of particle, and ω is inertia weight, and c is Studying factors, r are the random number generated on [0,1], choose ω=0.8, c=1.48；
(3d) judges global optimum particle GbestWhether convergence criterion, i.e. G are metbestCorresponding rear-wheel corner δrWith it is attached Add yaw moment MBSWhether min f (x is meti)≤0.02, if satisfied, going to step (3f)；If not satisfied, continuing in next step Suddenly；
Number of threshold values l is arranged in (3e), generates random number p, if l > p, updates population position using formula (9)；If l < p, Population position is updated using formula (10), goes to step (3d) after updating every time；Black hole search mechanisms update particle position formula It is as follows:
In formula,Current global optimum when for the number of iterations being t, R are that the globally optimal solution of setting nearby searches for half Diameter, rand are random number on [0,1] generated；
(3f) exports rear-wheel corner δrWith additional yaw moment MBS。
In the step (4), the four-wheel steering and differential braking jointly control strategy, which both can use four It rotates to the yaw moment for sharing a part, reduces impact caused by differential braking, also compensate for four-wheel steering and individually control When the shortcomings that；Based on this, rear-wheel corner δ is added on the basis of formula (6)rWith additional yaw moment MBSTo obtain ideal control Effect, the truck models differential equation jointly controlled are as follows:
In formula, m is fork truck quality, and u is forward speed, and q is goods weight, and v is the cargo rate of climb, and α is fork truck hypsokinesis Angle, γ are around z-axis yaw velocity, and β is side slip angle；IzFor around z-axis rotary inertia, kfFor front-wheel cornering stiffness, krIt is rear Take turns cornering stiffness, lfFor the distance of fork truck mass center to front axle, lrFor the distance of fork truck mass center to rear axle, δfFor front wheel angle, δrFor Rear-wheel corner.
Braked wheel selection rule in the step (4) are as follows: when left steering, as additional yaw moment MBSWhen greater than zero, system Driving wheel chooses inner rear wheel, as additional yaw moment MBSIt is small with zero when, braked wheel chooses outer front-wheel；When right turn, when additional sideway Torque MBSWhen greater than zero, braked wheel chooses outer front-wheel, as additional yaw moment MBSIt is small with zero when, braked wheel chooses inner rear wheel.
As shown from the above technical solution, the present invention has the advantages that first, the present invention establishes a kind of new comprising cargo The auto model of weight and cargo lifting speed, the model consider influence of the cargo lifting to fork truck lateral stability；Second, The present invention devises a kind of lateral stability controller of simplification particle swarm algorithm based on additional black hole mechanism, the control utensil There is the advantages of following ideal performance index real-time, quickly；Third solves lateral caused by cargo lifting under fork truck turning condition The problem of stability deficiency, improves fork truck working efficiency.
Detailed description of the invention
Fig. 1 is flow chart of the method for the present invention；
Fig. 2 is fork truck kinetic model figure in the present invention.
Specific embodiment
As shown in Figure 1, a kind of consider that cargo goes up and down the Optimal Control Strategy influenced on fork truck lateral stability, strategy packet Include following steps:
(1) auto model comprising goods weight and cargo lifting speed is established, determines that fork truck is worked as according to the auto model Ideal yaw velocity ω under preceding driving statusdWith ideal side slip angle βd；
(2) detection obtains the practical yaw velocity ω under fork truck current running staterealWith practical side slip angle βreal, then ideal yaw velocity ωdWith practical yaw velocity ωrealActual difference Δ ω, and ideal side slip angle βdWith practical side slip angle βrealActual difference Δ β be respectively as follows: Δ ω=ωd-ωreal, Δ β=βd-βreal；
(3) according to the actual difference Δ ω and actual difference Δ β, using the simplification particle swarm algorithm of additional black hole mechanism It calculates and obtains rear-wheel corner δrWith additional yaw moment MBS；
(4) according to the rear-wheel corner δrWith additional yaw moment MBS, and combine control with differential braking according to four-wheel steering System strategy, braked wheel selection rule jointly control fork truck.
In the step (1), establish the auto model comprising goods weight and cargo lifting speed as follows into Row:
Fork truck differential equation of motion are as follows:
In formula, FyFor side force of tire, m is fork truck quality, vcFor side velocity, u is forward speed, and γ is around z-axis sideway Angular speed, MzFor tyre moment, IzFor around z-axis rotary inertia；Z-axis is the z-axis of cartesian coordinate system；
It is in a linear relationship between side force of tire and side drift angle under low speed, small angle tower vehicle condition, therefore, above formula variation are as follows:
In formula, FfFor front tyre lateral force, FrFor rear tyre lateral force, kfFor front-wheel cornering stiffness, krFor rear wheel-side Inclined rigidity, βfFor front-wheel side drift angle, βrFor rear-wheel side drift angle, lfFor the distance of fork truck mass center to front axle, lrIt is fork truck mass center to rear The distance of axis；The low speed refers to 0 to 15km/h, and the small angle tower refers to front wheel angle 0 to 0.5rad；
The cornering stiffness and side drift angle of front and back wheel determine the size of front and back tire action force:
In formula, δfFor front wheel angle, δrFor rear-wheel corner；β is side slip angle；
Formula (3) are substituted into formula (2), abbreviation is at side slip angle and yaw velocity expression formula are as follows:
Different from conventional forklift model, consider that fork truck synthesizes gravity center shift under cargo jacking conditions, above-mentioned fork truck mass center is extremely The distance l of front axlefAre as follows:
Wherein, lf0Distance of the center of gravity away from front axle centre line under description of the goods is not added for fork truck；y0For cargo under initial situation Horizontal distance of the center of gravity away from forklift front bridge center line, t are the cargo rise time, and α is fork truck back rake angle；Q is goods weight, and v is The cargo rate of climb；
Gravity center shift formula, that is, formula (5) is synthesized in conjunction with fork truck, obtains considering that fork truck includes goods weight and cargo lifting speed The auto model of degree:
In the step (1), the ideal yaw velocity ωdWith ideal side slip angle βdIt obtains as follows:
By ideal side slip angle βdIt is set as 0, it may be assumed that βd=0；
Ideal yaw velocity ωdAcquisition pattern it is as follows:
Forward speed u, front wheel angle δ of the fork truck under current running state are obtained using sensor measurementf, cargo rise Speed v and goods weight q；
The ideal yaw velocity ω for obtaining fork truck is calculated by formula (7)d:
Wherein, GrIt is front-wheel steer fork truck yaw velocity to the steady-state gain of front wheel steering angle,K is The truck stability factor,μ is tire and pavement maximum attachment coefficient, kfFor front-wheel cornering stiffness, krFor Rear-wheel cornering stiffness, lfFor the distance of fork truck mass center to front axle, lrFor the distance of fork truck mass center to rear axle, g is acceleration of gravity, m For fork truck quality, L=lf+lr。
Rear-wheel corner δ is obtained in the step (3)rWith additional yaw moment MBSCalculation method it is specific as follows:
(3a) generates 30 population individual α i at random, and each individual is about rear-wheel corner δrWith additional yaw moment MBS Bivector, using them as initial population Q1, i=1,2...30；
(3b) initializes population position, speed, calculates each particle fitness according to particle fitness calculation formula (8) Value；
minf(xi)=K1|β-βd|+K2|γ-γd| (8)
In formula, β and γ are wherein about rear-wheel corner δrWith additional yaw moment MBSFunction, specially each particle Corresponding yaw velocity and side slip angle value, βdFor ideal yaw velocity, γdFor ideal side slip angle, K1,K2For Normalization factor is chosen for respectivelyGlobal optimum's particle is to calculate resulting value most granule by formula (8) Son is set as Gbest；
(3c) updates population position to the 80% of maximum evolutionary generation using particle swarm algorithm is simplified, and simplifies population and calculates It is as follows that method updates particle position formula:
In formula, t indicates current iteration number, and P is particle current location, and V is the speed of particle, and ω is inertia weight, and c is Studying factors, r are the random number generated on [0,1], choose ω=0.8, c=1.48；
(3d) judges global optimum particle GbestWhether convergence criterion, i.e. G are metbestCorresponding rear-wheel corner δrWith it is attached Add yaw moment MBSWhether minf (x is meti)≤0.02, if satisfied, going to step (3f)；If not satisfied, continuing next step；
Number of threshold values l is arranged in (3e), generates random number p, if l > p, updates population position using formula (9)；If l < p, Population position is updated using formula (10), goes to step (3d) after updating every time；Black hole search mechanisms update particle position formula It is as follows:
In formula,Current global optimum when for the number of iterations being t, R are the neighbouring search radius of globally optimal solution of setting, Rand is random number on [0,1] generated；
(3f) exports rear-wheel corner δrWith additional yaw moment MBS。
In the step (4), the four-wheel steering and differential braking jointly control strategy, which both can use four It rotates to the yaw moment for sharing a part, reduces impact caused by differential braking, also compensate for four-wheel steering and individually control When the shortcomings that；Based on this, rear-wheel corner δ is added on the basis of formula (6)rWith additional yaw moment MBSTo obtain ideal control Effect, the truck models differential equation jointly controlled are as follows:
In formula, m is fork truck quality, and u is forward speed, and q is goods weight, and v is the cargo rate of climb, and α is fork truck hypsokinesis Angle, γ are around z-axis yaw velocity, and β is side slip angle；IzFor around z-axis rotary inertia, kfFor front-wheel cornering stiffness, krIt is rear Take turns cornering stiffness, lfFor the distance of fork truck mass center to front axle, lrFor the distance of fork truck mass center to rear axle, δfFor front wheel angle, δrFor Rear-wheel corner.
Braked wheel selection rule in the step (4) are as follows: when left steering, as additional yaw moment MBSWhen greater than zero, system Driving wheel chooses inner rear wheel, as additional yaw moment MBSIt is small with zero when, braked wheel chooses outer front-wheel；When right turn, when additional sideway Torque MBSWhen greater than zero, braked wheel chooses outer front-wheel, as additional yaw moment MBSIt is small with zero when, braked wheel chooses inner rear wheel.
As shown in Fig. 2, fork truck is moved forward with speed u, fork truck back rake angle is α, and loading cargo mass is q, process of turning Middle cargo rises a distance s with the speed of v, and fork truck synthesizes center of gravity and is changed to o ', cargo weight by o since cargo rises center of gravity Horizontal distance of the heart away from forklift front bridge center line is by y0Variation is y ', and fork truck synthesizes the distance of center of gravity to front axle by lf0Variation is lf, the distance of fork truck synthesis center of gravity to rear axle is by lr0Variation is lr。
In conclusion the present invention establishes a kind of new auto model comprising goods weight and cargo lifting speed, it should Model considers influence of the cargo lifting to fork truck lateral stability；The present invention devises a kind of letter based on additional black hole mechanism Change the lateral stability controller of particle swarm algorithm, which has the advantages that follow ideal performance index real-time, quickly；This Invention solves the problems, such as that cargo goes up and down caused lateral stability deficiency under fork truck turning condition, improves fork truck work effect Rate.

Claims (6)

1. a kind of consider that cargo goes up and down the Optimal Control Strategy influenced on fork truck lateral stability, it is characterised in that: strategy packet Include following steps:
(1) auto model comprising goods weight and cargo lifting speed is established, fork truck current line is determined according to the auto model Sail the ideal yaw velocity ω under statedWith ideal side slip angle βd；
(2) detection obtains the practical yaw velocity ω under fork truck current running staterealWith practical side slip angle βreal, then Ideal yaw velocity ωdWith practical yaw velocity ωrealActual difference Δ ω, and ideal side slip angle βdWith reality Border side slip angle βrealActual difference Δ β be respectively as follows: Δ ω=ωd-ωreal, Δ β=βd-βreal；
(3) it according to the actual difference Δ ω and actual difference Δ β, is calculated using the simplification particle swarm algorithm of additional black hole mechanism Obtain rear-wheel corner δrWith additional yaw moment MBS；
(4) according to the rear-wheel corner δrWith additional yaw moment MBS, and jointly control plan according to four-wheel steering and differential braking Slightly, braked wheel selection rule jointly controls fork truck.
2. according to claim 1 consider that cargo goes up and down the Optimal Control Strategy influenced on fork truck lateral stability, special Sign is: in the step (1), establish the auto model comprising goods weight and cargo lifting speed as follows into Row:
Fork truck differential equation of motion are as follows:
In formula, FyFor side force of tire, m is fork truck quality, vcFor side velocity, u is forward speed, and γ is around z-axis yaw angle speed Degree, MzFor tyre moment, IzFor around z-axis rotary inertia；Z-axis is the z-axis of cartesian coordinate system；
It is in a linear relationship between side force of tire and side drift angle under low speed, small angle tower vehicle condition, therefore, above formula variation are as follows:
In formula, FfFor front tyre lateral force, FrFor rear tyre lateral force, kfFor front-wheel cornering stiffness, krIt is rigid for rear-wheel lateral deviation Degree, βfFor front-wheel side drift angle, βrFor rear-wheel side drift angle, lfFor the distance of fork truck mass center to front axle, lrFor fork truck mass center to rear axle Distance；The low speed refers to 0 to 15km/h, and the small angle tower refers to front wheel angle 0 to 0.5rad；
The cornering stiffness and side drift angle of front and back wheel determine the size of front and back tire action force:
In formula, δfFor front wheel angle, δrFor rear-wheel corner；β is side slip angle；
Formula (3) are substituted into formula (2), abbreviation is at side slip angle and yaw velocity expression formula are as follows:
Different from conventional forklift model, consider that fork truck synthesizes gravity center shift, above-mentioned fork truck mass center to front axle under cargo jacking conditions Distance lfAre as follows:
Wherein, lf0Distance of the center of gravity away from front axle centre line under description of the goods is not added for fork truck；y0For center of gravity of goods under initial situation Horizontal distance away from forklift front bridge center line, t are the cargo rise time, and α is fork truck back rake angle；Q is goods weight, and v is cargo The rate of climb；
Gravity center shift formula, that is, formula (5) is synthesized in conjunction with fork truck, obtains considering that fork truck includes goods weight and cargo lifting speed Auto model:
3. according to claim 1 consider that cargo goes up and down the Optimal Control Strategy influenced on fork truck lateral stability, special Sign is: in the step (1), the ideal yaw velocity ωdWith ideal side slip angle βdIt obtains as follows:
By ideal side slip angle βdIt is set as 0, it may be assumed that βd=0；
Ideal yaw velocity ωdAcquisition pattern it is as follows:
Forward speed u, front wheel angle δ of the fork truck under current running state are obtained using sensor measurementf, cargo rate of climb v With goods weight q；
The ideal yaw velocity ω for obtaining fork truck is calculated by formula (7)d:
Wherein, GrIt is front-wheel steer fork truck yaw velocity to the steady-state gain of front wheel steering angle,K is fork truck Stability factor,μ is tire and pavement maximum attachment coefficient, kfFor front-wheel cornering stiffness, krFor rear-wheel Cornering stiffness, lfFor the distance of fork truck mass center to front axle, lrFor the distance of fork truck mass center to rear axle, g is acceleration of gravity, and m is fork Vehicle quality, L=lf+lr。
4. according to claim 1 consider that cargo goes up and down the Optimal Control Strategy influenced on fork truck lateral stability, special Sign is: rear-wheel corner δ is obtained in the step (3)rWith additional yaw moment MBSCalculation method it is specific as follows:
(3a) generates 30 population individual α at randomi, each individual is about rear-wheel corner δrWith additional yaw moment MBSTwo Dimensional vector, using them as initial population Q1, i=1,2...30；
(3b) initializes population position, speed, calculates each particle fitness value according to particle fitness calculation formula (8)；
min f(xi)=K1|β-βd|+K2|γ-γd| (8)
In formula, β and γ are wherein about rear-wheel corner δrWith additional yaw moment MBSFunction, specially each particle is corresponding Yaw velocity and side slip angle value, βdFor ideal yaw velocity, γdFor ideal side slip angle, K1,K2For normalizing Change the factor, is chosen for respectivelyGlobal optimum's particle be by formula (8) calculate resulting value smallest particles, if For Gbest；
(3c) updates population position to the 80% of maximum evolutionary generation using particle swarm algorithm is simplified, and simplifies particle swarm algorithm more New particle location formula is as follows:
In formula, t indicates that current iteration number, P are particle current locations, and V is the speed of particle, and ω is inertia weight, and c is study The factor, r are the random number generated on [0,1], choose ω=0.8, c=1.48；
(3d) judges global optimum particle GbestWhether convergence criterion, i.e. G are metbestCorresponding rear-wheel corner δrWith additional cross Put torque MBSWhether min f (x is meti)≤0.02, if satisfied, going to step (3f)；If not satisfied, continuing next step；
Number of threshold values l is arranged in (3e), generates random number p, if l > p, updates population position using formula (9)；If l < p is used Formula (10) updates population position, goes to step (3d) after updating every time；It is as follows that black hole search mechanisms update particle position formula:
In formula,Current global optimum when for the number of iterations being t, R are the neighbouring search radius of globally optimal solution of setting, rand For random number on [0,1] of generation；
(3f) exports rear-wheel corner δrWith additional yaw moment MBS。
5. according to claim 1 consider that cargo goes up and down the Optimal Control Strategy influenced on fork truck lateral stability, special Sign is: in the step (4), the four-wheel steering and differential braking jointly control strategy, which both can use four It rotates to the yaw moment for sharing a part, reduces impact caused by differential braking, also compensate for four-wheel steering and individually control When the shortcomings that；Based on this, rear-wheel corner δ is added on the basis of formula (6)rWith additional yaw moment MBSTo obtain ideal control Effect, the truck models differential equation jointly controlled are as follows:
In formula, m is fork truck quality, and u is forward speed, and q is goods weight, and v is the cargo rate of climb, and α is fork truck back rake angle, γ For around z-axis yaw velocity, β is side slip angle；IzFor around z-axis rotary inertia, kfFor front-wheel cornering stiffness, krFor rear wheel-side Inclined rigidity, lfFor the distance of fork truck mass center to front axle, lrFor the distance of fork truck mass center to rear axle, δfFor front wheel angle, δrFor rear-wheel Corner.
6. according to claim 1 consider that cargo goes up and down the Optimal Control Strategy influenced on fork truck lateral stability, special Sign is: the braked wheel selection rule in the step (4) are as follows: when left steering, as additional yaw moment MBSWhen greater than zero, braking Wheel chooses inner rear wheel, as additional yaw moment MBSIt is small with zero when, braked wheel chooses outer front-wheel；When right turn, when additional sideway power Square MBSWhen greater than zero, braked wheel chooses outer front-wheel, as additional yaw moment MBSIt is small with zero when, braked wheel chooses inner rear wheel.
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