CN103121447B - A kind of bend preventing side sliding and side turning autonomous cruise speed system and method - Google Patents

Abstract

The present invention relates to safety assistant driving and field of intelligent control, disclose a kind of bend preventing side sliding and side turning autonomous cruise speed system and method, vehicle-mounted autonomous cruise speed system is adopted to control intelligent vehicle, first bend curvature information is obtained, next is translated into digital signal and inputs vehicle-mounted microprocessor, safe speed computing module calculates bend criticality safety speed of a motor vehicle serviceable car set sensor and records current vehicle speed, then safe condition judge module judges current vehicle speed and the criticality safety speed of a motor vehicle, finally utilize system automatic control module to control intelligent vehicle and pass through bend smoothly.Present invention, avoiding the limitation only utilizing vehicle kinematics controller to realize track following, the Study on Vehicle Dynamic Control device of design ensure that the practicability that straight way automatic retarding and bend track keep and real-time, improve the precision that safe speed calculates, adopt the dynamics Controlling rule comprising equivalent control and switching controls, can effectively suppress system chatter phenomenon, overcome the impact of external interference.

Description

A kind of bend preventing side sliding and side turning autonomous cruise speed system and method

Technical field

The present invention relates to safety assistant driving and field of intelligent control, particularly a kind of bend preventing side sliding and side turning autonomous cruise speed system and method.

Background technology

The method of designing of vehicle anti-skidding rollover autonomous cruise speed system is a kind of safety assistant driving technology relatively more conventional on current intelligent vehicle, its technical essential is followed the tracks of the vehicle running state of expectation, it relies on control algorithm to select, relevant with the impact of friction, Parameter Perturbation and external interference, straight way section has higher safe speed design accuracy and track following effect, improve vehicle safety and road-holding property, reach the object improving preventing side sliding and side turning control accuracy.

In straight way section, although the design theory of vehicle anti-skidding rollover autonomous cruise speed system is substantially perfect, but the impact of many situations such as road superelevation is there is for bend section, still there is following defect in the design theory of vehicle anti-skidding rollover autonomous cruise speed system: in bend section, be difficult to the precision ensureing that safe speed calculates, affect by vehicle kinematics model is circumscribed, control system lacks practical value, need the method for designing studying dynamics Controlling rule, need to improve quick, accurately tracking and Existence of Global Stable the characteristic of system controller.

Summary of the invention

The object of the invention is: be solve the technical matters that prior art exists, a kind of bend preventing side sliding and side turning autonomous cruise speed system and method are provided, detect in real time the radius of curvature of bend and consider the compensating action of road superelevation, improving the precision that safe speed calculates; The present invention includes the dynamics Controlling rule of equivalent control and switching controls, can effectively suppress system chatter phenomenon, overcome the impact of external interference.

For achieving the above object, the technical solution used in the present invention is: provide a kind of bend preventing side sliding and side turning autonomous cruise speed system, vehicle-mounted autonomous cruise speed system is adopted to control intelligent vehicle, described vehicle-mounted autonomous cruise speed system comprises: bend curvature identification module, safe speed computing module, safe condition judge module and system automatic control module, and above-mentioned module successively signal connects.

Described bend curvature identification module is used for the curvature information detecting curve ahead in real time, by following process implementation:

Bend curvature identification module utilizes vehicle-borne CCD to obtain road image, by Image semantic classification, adopts Hough transform method matching road model and rebuilds bend lane mark.

The optical axis of pick up camera is parallel to the ground, and due on a highway, surface slope is very little, supposes any point on road surface ycoordinate is equal, is the distance of pick up camera photocentre to ground h; For space any point P, its world coordinates ( x, y, z) and image coordinate ( x, y) there is following relation, it is consistent with global coordinate system initial point namely to move perspective projection center:

Wherein, ( x, y, z) be world coordinates; ( x, y) be image coordinate; hfor pick up camera photocentre is to the distance on ground; ffor focal length.

Utilize coordinate transform to change lane mark image, appoint the four groups of points got on the inside lane edge line of space, often organize each three points, its world coordinates is respectively P ₁( x ₁, y ₁, z ₁), P ₂( x ₂, y ₂, z ₂), P ₃( x ₃, y ₃, z ₃), it is substituted into circular arc formula respectively

Wherein, ( a, b) be the center of circle of circular arc lane mark; rfor the radius of curvature of lane mark.

Calculate four suite rate radius values r ₁, r ₂, r ₃with r ₄, respectively compared with the road curvature estimated by the path coordinate utilizing vehicle GPS/generalized information system to export, be reliable curvature information in error allowed band, ask the aviation value of reliable curvature radius to be the radius of curvature of curve ahead.

Described safe speed computing module is for calculating the bend criticality safety speed of a motor vehicle v, by following process implementation:

Safe speed computing module calculates the bend criticality safety speed of a motor vehicle v;

When the centnifugal force produced when vehicle bend travels is less than or equal to road adherence, automobile does not break away; Will consider that road superelevation can offset part centrifugal power, computing formula is simultaneously:

Wherein, ffor the centnifugal force produced during running car; f _h for the part centrifugal power that road superelevation is offset; f _x for traction; mfor car mass; v ₁for there is not the safe speed breakked away; rfor bend radius of curvature; i _h for the transverse slope of road superelevation; φfor lateral adhesion coefficient; gfor acceleration due to gravity.

Obtain the safe speed that vehicle does not occur to break away v ₁, computing formula is:

Wherein, v ₁for there is not the safe speed breakked away, φfor lateral adhesion coefficient, gfor acceleration due to gravity, rfor bend radius of curvature, i _h for the transverse slope of road superelevation.

When vehicle bend travels, the condition not occurring to turn on one's side is that bank moment is not more than aligning torque, considers that the computing formula of road superelevation is:

Wherein, Σ m _ф for the bank moment caused by centrifugal automobile power; Σ mfor the bank moment that the part centrifugal power offset by road superelevation causes; Σ tfor aligning torque; mfor car mass; v ₂for there is not the safe speed of turning on one's side; rfor bend radius of curvature; hfor vehicle centroid height; f _h for the part centrifugal power that road superelevation is offset; gfor acceleration due to gravity; bfor wheelspan; i _h for the transverse slope of road superelevation; φfor lateral adhesion coefficient.

Calculate the safe speed that vehicle does not occur to turn on one's side v ₂, computing formula is:

Wherein, v ₂for there is not the safe speed of turning on one's side, bfor wheelspan, hfor vehicle centroid height, gfor acceleration due to gravity, rfor bend radius of curvature, i _h for the transverse slope of road superelevation, φfor lateral adhesion coefficient.

For ensureing the safety that vehicle bend travels, avoid occurring the dangerous working conditions such as sideslip and rollover, the speed of a motor vehicle must meet above-mentioned two kinds of constraint conditions simultaneously, namely

When above formula gets equal sign, vfor the criticality safety speed of a motor vehicle, v ₁for there is not the safe speed breakked away, v ₂for there is not the safe speed of turning on one's side.

Described safe condition judge module is to current vehicle speed and the criticality safety speed of a motor vehicle vjudge, comprise two kinds of situations:

When current vehicle speed is greater than the criticality safety speed of a motor vehicle vtime, system automatic alarm, alerting signal inputs vehicle-mounted microprocessor, the controller action of maneuvering system automatic control module, and vehicle autobrake is slowed down, and in whole braking deceleration process, if the speed of a motor vehicle is in high-velocity section, desirable deceleration/decel constantly increases; When the speed of a motor vehicle is down to low speed section, for avoiding braking deceleration excessive, desirable deceleration/decel remains unchanged until the speed of a motor vehicle is kept to safe speed, by bend, arranges longitudinal braking deceleration thus , that is:

Wherein: a ₁, a ₂for arithmetic number; 0 ~ t ₁for high-velocity section; t ₁~ t ₂for low speed section.

In good time the effect of described system automatic control module regulates and controls travel condition of vehicle, realizes straight way automatic retarding and the maintenance of bend track, comprising: kinematic controller and Dynamics Controller.

The function of described kinematic controller is: when current vehicle speed is greater than the criticality safety speed of a motor vehicle vtime, vehicle enters the straight way autobrake decelerating phase, and detailed process is as follows:

First, vehicle-mounted microprocessor receiving system alerting signal, is taking vehicle as the local coordinate system of reference mijunder, initialization system arbitrary initial error p _e =[ x _e y _e θ _e ] ^t .

Then, according to kinematics control law

Wherein, k ₁, k ₂, k ₃be arithmetic number; lfor the distance between shafts of front and back wheel; v _r for line of reference speed; φ _r for reference front wheel steering angle; v _c for expecting linear velocity; φ _c for expecting front wheel steering angle; p _e =[ x _e y _e θ _e ] ^t for the position and attitude error of vehicle movement under local coordinate system;

Determine bounded control inputs , follow the tracks of the vehicle reference pose under local coordinate system p _r =[ x _r y _r θ _r ] ^t , thus realize time ;

Wherein, pfor the current pose of vehicle; p _r for vehicle reference bit appearance under local coordinate system.

Finally, system control signal expects that linear velocity and front wheel steering angle input vehicle-mounted microprocessor, the kinematic controller effect of maneuvering system automatic control module, makes the current running velocity of vehicle vreduce to the criticality safety speed of a motor vehicle now v _c .

The function of described Dynamics Controller is: when current vehicle speed is less than or equal to the criticality safety speed of a motor vehicle vtime, intelligent vehicle enters bend and keeps stage smooth in bend, and detailed process is as follows:

First, vehicle current vehicle speed vrecorded by onboard sensor, expect running velocity with vehicle v _c input vehicle-mounted microprocessor simultaneously.

Then, restrain according to dynamics Controlling

Wherein, α ₁, α ₂>0; β ₁, β ₂>0; mfor car mass; lfor the distance between shafts of front and back wheel; ifor vehicle is around the rotor inertia of vertical axis; vfor the linear velocity of vehicle rear axle center-point; φfor front wheel steering angle; v _c for expecting linear velocity; φ _c for expecting front wheel steering angle; e _v for speed system error; e _φ for front wheel angle systematic error; s _v ( t) be PI type speed sliding-mode surface; s _φ ( t) be PI type front wheel angle sliding-mode surface;

Determine bounded control inputs , follow the tracks of vehicle and expect running velocity , thus realize time ;

Wherein, vfor vehicle real-world operation speed; v _c for running velocity expected by vehicle.

Finally, system control signal driving/braking power and rotating torque input vehicle-mounted microprocessor, the Dynamics Controller effect of maneuvering system automatic control module, make vehicle with current running velocity vsafety bend.

A kind of bend preventing side sliding and side turning autocontrol method, specifically comprises the following steps:

Step 1: the path coordinate that bend curvature identification module utilizes vehicle GPS/generalized information system to export estimates road curvature, and utilize vehicle-borne CCD to obtain road image, calculate turning radius by process image, matching road model, obtain the curvature information of curve ahead.

Step 2: be digital signal by the bend radius of curvature convert information of acquisition, after inputting vehicle-mounted microprocessor, safe speed computing module calculates the bend criticality safety speed of a motor vehicle v.

When the centnifugal force produced when vehicle bend travels is less than or equal to road adherence, automobile does not break away; Will consider that road superelevation can offset part centrifugal power, computing formula is simultaneously:

Wherein, ffor the centnifugal force produced during running car; f _h for the part centrifugal power that road superelevation is offset; f _x for traction; mfor car mass; v ₁for there is not the safe speed breakked away; rfor bend radius of curvature; i _h for the transverse slope of road superelevation; φfor lateral adhesion coefficient; gfor acceleration due to gravity.

Obtain the safe speed that vehicle does not occur to break away v ₁, computing formula is:

Wherein, v ₁for there is not the safe speed breakked away, φfor lateral adhesion coefficient, gfor acceleration due to gravity, rfor bend radius of curvature, i _h for the transverse slope of road superelevation.

When vehicle bend travels, the condition not occurring to turn on one's side is that bank moment is not more than aligning torque, considers that the computing formula of road superelevation is:

Wherein, Σ m _ф for the bank moment caused by centrifugal automobile power; Σ mfor the bank moment that the part centrifugal power offset by road superelevation causes; Σ tfor aligning torque; mfor car mass; v ₂for there is not the safe speed of turning on one's side; rfor bend radius of curvature; hfor vehicle centroid height; f _h for the part centrifugal power that road superelevation is offset; gfor acceleration due to gravity; bfor wheelspan; i _h for the transverse slope of road superelevation; φfor lateral adhesion coefficient.

Calculate the safe speed that vehicle does not occur to turn on one's side v ₂, computing formula is:

Wherein, v ₂for there is not the safe speed of turning on one's side, bfor wheelspan, hfor vehicle centroid height, gfor acceleration due to gravity, rfor bend radius of curvature, i _h for the transverse slope of road superelevation, φfor lateral adhesion coefficient.

For ensureing the safety that vehicle bend travels, avoid occurring the dangerous working conditions such as sideslip and rollover, the speed of a motor vehicle must meet above-mentioned two kinds of constraint conditions simultaneously, namely

When above formula gets equal sign, vfor the criticality safety speed of a motor vehicle, v ₁for there is not the safe speed breakked away, v ₂for there is not the safe speed of turning on one's side.

Step 3: serviceable car set sensor records current vehicle speed, in vehicle-mounted microprocessor, safe condition judge module is to current vehicle speed and the criticality safety speed of a motor vehicle vjudge, comprise two kinds of situations:

When current vehicle speed is greater than the criticality safety speed of a motor vehicle vtime, system automatic alarm, alerting signal inputs vehicle-mounted microprocessor, the controller action of maneuvering system automatic control module, and vehicle autobrake is slowed down, and in whole braking deceleration process, if the speed of a motor vehicle is in high-velocity section, desirable deceleration/decel constantly increases; When the speed of a motor vehicle is down to low speed section, for avoiding braking deceleration excessive, desirable deceleration/decel remains unchanged until the speed of a motor vehicle is kept to safe speed, by bend, arranges longitudinal braking deceleration thus , that is:

Wherein: a ₁, a ₂for arithmetic number; 0 ~ t ₁for high-velocity section; t ₁~ t ₂for low speed section.

Step 4: system automatic control module controls intelligent vehicle smoothly by bend, comprises the following steps:

Step 4.1.1: vehicle-mounted microprocessor receiving system alerting signal, is taking vehicle as the local coordinate system of reference mijunder, initialization system arbitrary initial error p _e =[ x _e y _e θ _e ] ^t .

Step 4.1.2: according to kinematics control law

Wherein, k ₁, k ₂, k ₃be arithmetic number; lfor the distance between shafts of front and back wheel; v _r for line of reference speed; φ _r for reference front wheel steering angle; v _c for expecting linear velocity; φ _c for expecting front wheel steering angle; p _e =[ x _e y _e θ _e ] ^t for the position and attitude error of vehicle movement under local coordinate system.

Determine bounded control inputs , follow the tracks of the vehicle reference pose under local coordinate system p _r =[ x _r y _r θ _r ] ^t , thus realize time ;

Wherein, pfor the current pose of vehicle; p _r for vehicle reference bit appearance under local coordinate system.

Step 4.1.3: system control signal expects that linear velocity and front wheel steering angle input vehicle-mounted microprocessor, the kinematic controller effect of maneuvering system automatic control module, makes the current running velocity of vehicle vreduce to the criticality safety speed of a motor vehicle now v _c .

Step 4.2: when current vehicle speed is less than or equal to the criticality safety speed of a motor vehicle vtime, Dynamics Controller controls intelligent vehicle and enters bend and keep stage smooth in bend, comprises following sub-step:

Step 4.2.1: vehicle current vehicle speed vrecorded by onboard sensor, expect running velocity with vehicle v _c input vehicle-mounted microprocessor simultaneously;

Step 4.2.2: restrain according to dynamics Controlling

Wherein, α ₁, α ₂>0; β ₁, β ₂>0; mfor car mass; lfor the distance between shafts of front and back wheel; ifor vehicle is around the rotor inertia of vertical axis; vfor the linear velocity of vehicle rear axle center-point; φfor front wheel steering angle; v _c for expecting linear velocity; φ _c for expecting front wheel steering angle; e _v for speed system error; e _φ for front wheel angle systematic error; s _v ( t) be PI type speed sliding-mode surface; s _φ ( t) be PI type front wheel angle sliding-mode surface.

Determine bounded control inputs , follow the tracks of vehicle and expect running velocity , thus realize time ;

Wherein, vfor vehicle real-world operation speed; v _c for running velocity expected by vehicle.

Step 4.2.3: system control signal driving/braking power and rotating torque input vehicle-mounted microprocessor, the Dynamics Controller effect of maneuvering system automatic control module, makes vehicle with current running velocity vsafety bend.

The foundation of described kinematic controller comprises the following steps:

The first step: set up world coordinate system oxyunder vehicle kinematics model, formula is:

Wherein, lfor the distance between shafts of front and back wheel, θfor edge xthe Current vehicle sense of motion that axle conter clockwise obtains; vfor the linear velocity of vehicle rear axle center-point; p=[ x y θ] ^t for the current pose of vehicle.

Second step: definition local coordinate system mijlower vehicle reference bit appearance p _r =[ x _r y _r θ _r ] ^t with the position and attitude error of vehicle movement p _e =[ x _e y _e θ _e ] ^t ,

Wherein, p _r =[ x _r y _r θ _r ] ^t for vehicle reference bit appearance under local coordinate system; p _e =[ x _e y _e θ _e ] ^t for the position and attitude error of vehicle movement under local coordinate system; θfor edge xthe Current vehicle sense of motion that axle conter clockwise obtains.

Vehicle movement meets nonholonomic constraint, and formula is:

Wherein, lfor the distance between shafts of front and back wheel; θfor edge xthe Current vehicle sense of motion that axle conter clockwise obtains; φfor front wheel steering angle; p=[ x y θ] ^t for the current pose of vehicle.

Differentiate obtains the vehicle position and attitude error differential equation :

Wherein, p _e =[ x _e y _e θ _e ] ^t for the position and attitude error of vehicle movement under local coordinate system; p _r =[ x _r y _r θ _r ] ^t for vehicle reference bit appearance under local coordinate system; lfor the distance between shafts of front and back wheel; φfor front wheel steering angle; φ _r for reference front wheel steering angle; vfor the linear velocity of vehicle rear axle center-point; v _r for line of reference speed.

3rd step: adopt Integrator backstepping method to set up kinematics control module, select suitable kinematics control law , make time , for dynamics Controlling module provides linear velocity and the front wheel steering angle of reference, the process setting up kinematics control module by Integrator backstepping method is as follows:

First, Lyapunov function is selected v ₁;

Wherein: k ₂>0; p _e =[ x _e y _e θ _e ] ^t for the position and attitude error of vehicle movement under local coordinate system.

Then, differentiate v ₁, and by the vehicle position and attitude error differential equation substitute into derived function ;

Wherein, k ₂>0; lfor the distance between shafts of front and back wheel; φfor front wheel steering angle; φ _r for reference front wheel steering angle; vfor the linear velocity of vehicle rear axle center-point; v _r for line of reference speed; p _e =[ x _e y _e θ _e ] ^t for the position and attitude error of vehicle movement under local coordinate system.

Finally, according to select suitable kinematics control law , make time , the stability of system is judged by Lyapunov criterion;

Select

Wherein, k ₁, k ₂, k ₃be arithmetic number; lfor the distance between shafts of front and back wheel; v _r for line of reference speed; φ _r for reference front wheel steering angle; v _c for expecting linear velocity; φ _c for expecting front wheel steering angle; p _e =[ x _e y _e θ _e ] ^t for the position and attitude error of vehicle movement under local coordinate system.

As kinematics control law, due to

Wherein, k ₁, k ₂, k ₃be arithmetic number; lfor the distance between shafts of front and back wheel; vfor the linear velocity of vehicle rear axle center-point; p _e =[ x _e y _e θ _e ] ^t for the position and attitude error of vehicle movement under local coordinate system;

Know according to Lyapunov criterion, in global scope [ x _e y _e θ _e ] ^t bounded and

System has global stability;

Wherein: p _e =[ x _e y _e θ _e ] ^t for the position and attitude error of vehicle movement under local coordinate system.

The foundation of described Dynamics Controller comprises the following steps:

The first step: intelligent vehicle kinetic model is reduced to wheel type machine human occupant dynamic model, that is:

Wherein, τ ₁, τ ₂be respectively driving/braking power and the rotating torque of intelligent vehicle; mfor car mass; ifor vehicle is around the rotor inertia of vertical axis; vfor the linear velocity of vehicle rear axle center-point; wfor vehicle cireular frequency.

According to vehicle kinematics model and kinetic model, derive front wheel steering angle speed formula;

Wherein, τ ₂for the rotating torque of intelligent vehicle; lfor the distance between shafts of front and back wheel; ifor vehicle is around the rotor inertia of vertical axis; φfor front wheel steering angle; vfor the linear velocity of vehicle rear axle center-point.

Second step: adopt the design of PI sliding-mode method to comprise the dynamics Controlling module of equivalent control and switching controls, the output of kinematics control module as with reference to input, export and be , make time , wherein, τ ₁, τ ₂be respectively driving/braking power and the rotating torque of intelligent vehicle;

Implementation procedure is as follows:

First, define system error e=[ e _v e _φ ] ^t , namely

Wherein, e _v for speed system error; e _φ for front wheel angle systematic error; vfor the linear velocity of vehicle rear axle center-point; φfor front wheel steering angle; v _c for expecting linear velocity; φ _c for expecting front wheel steering angle;

Select PI type sliding-mode surface s( t):

Wherein, α ₁, α ₂>0; e _v for speed system error; e _φ for front wheel angle systematic error.

Secondly, differentiate PI type sliding-mode surface, order , obtain system equivalent control rule , formula is:

Wherein, α ₁, α ₂>0; mfor car mass; lfor the distance between shafts of front and back wheel; ifor vehicle is around the rotor inertia of vertical axis; vfor the linear velocity of vehicle rear axle center-point; φfor front wheel steering angle; v _c for expecting linear velocity; φ _c for expecting front wheel steering angle; e _v for speed system error; e _φ for front wheel angle systematic error;

Equivalent control can make state of the system remain on sliding-mode surface, but external interference inevitably exists, and therefore must consider switching controls , designed sliding formwork controls to comprise two parts: equivalent control and switching controls, namely

Namely

Wherein, α ₁, α ₂>0; β ₁, β ₂>0; mfor car mass; lfor the distance between shafts of front and back wheel; ifor vehicle is around the rotor inertia of vertical axis; vfor the linear velocity of vehicle rear axle center-point; φfor front wheel steering angle; v _c for expecting linear velocity; φ _c for expecting front wheel steering angle; e _v for speed system error; e _φ for front wheel angle systematic error; s _v ( t) be PI type speed sliding-mode surface; s _φ ( t) be PI type front wheel angle sliding-mode surface;

Make time .

Again, Lyapunov function is selected v ₂;

Wherein, s( t)=[ s _v ( t) s _φ ( t)] ^t for PI type sliding-mode surface.

Finally, differentiate v ₂, by sliding formwork control law substitute into derived function , judged the stability of system by Lyapunov criterion, formula is:

Wherein, β ₁, β ₂>0; mfor car mass; s _v ( t) be PI type speed sliding-mode surface; s _φ ( t) be PI type front wheel angle sliding-mode surface;

For have , system stability.

The invention has the beneficial effects as follows: present invention, avoiding the limitation only utilizing vehicle kinematics controller to realize track following, devise the Study on Vehicle Dynamic Control device that practical study is worth simultaneously, ensure that the practicability that straight way automatic retarding and bend track keep and real-time, from detecting the radius of curvature of bend in real time and considering the compensating action angularly of road superelevation, improve the precision that safe speed calculates, adopt the dynamics Controlling rule comprising equivalent control and switching controls, can effectively suppress system chatter phenomenon, overcome the impact of external interference.

Accompanying drawing explanation

Fig. 1 is the composition schematic diagram of a kind of bend preventing side sliding and side turning of the present invention autonomous cruise speed system.

Fig. 2 is a kind of bend preventing side sliding and side turning of the present invention autocontrol method diagram of circuit.

Fig. 3 is the system automatic control module schematic diagram be made up of kinematic controller and Dynamics Controller.

Fig. 4 is vehicle attained pose and reference pose schematic diagram in kinematic controller of the present invention.

Detailed description of the invention

Below in conjunction with drawings and Examples, the present invention is described in detail.

With reference to Fig. 1, a kind of bend preventing side sliding and side turning of the present invention autonomous cruise speed system, vehicle-mounted autonomous cruise speed system is adopted to control intelligent vehicle, described vehicle-mounted autonomous cruise speed system comprises: bend curvature identification module, safe speed computing module, safe condition judge module and system automatic control module, and above-mentioned module successively signal connects.

Described bend curvature identification module is used for the curvature information detecting curve ahead in real time, by following process implementation:

Bend curvature identification module utilizes vehicle-borne CCD to obtain road image, by Image semantic classification, adopts Hough transform method matching road model and rebuilds bend lane mark.

The optical axis of pick up camera is parallel to the ground, and due on a highway, surface slope is very little, supposes any point on road surface ycoordinate is equal, is the distance of pick up camera photocentre to ground h; For space any point P, its world coordinates ( x, y, z) and image coordinate ( x, y) there is following relation, it is consistent with global coordinate system initial point namely to move perspective projection center:

Wherein, ( x, y, z) be world coordinates; ( x, y) be image coordinate; hfor pick up camera photocentre is to the distance on ground; ffor focal length.

Utilize coordinate transform to change lane mark image, appoint the four groups of points got on the inside lane edge line of space, often organize each three points, its world coordinates is respectively P ₁( x ₁, y ₁, z ₁), P ₂( x ₂, y ₂, z ₂), P ₃( x ₃, y ₃, z ₃), it is substituted into circular arc formula respectively

Wherein, ( a, b) be the center of circle of circular arc lane mark; rfor the radius of curvature of lane mark.

Calculate four suite rate radius values r ₁, r ₂, r ₃with r ₄, respectively compared with the road curvature estimated by the path coordinate utilizing vehicle GPS/generalized information system to export, be reliable curvature information in error allowed band, ask the aviation value of reliable curvature radius to be the radius of curvature of curve ahead.

Described safe speed computing module is for calculating the bend criticality safety speed of a motor vehicle v, by following process implementation:

Safe speed computing module calculates the bend criticality safety speed of a motor vehicle v;

When the centnifugal force produced when vehicle bend travels is less than or equal to road adherence, automobile does not break away; Will consider that road superelevation can offset part centrifugal power, computing formula is simultaneously:

Wherein, ffor the centnifugal force produced during running car; f _h for the part centrifugal power that road superelevation is offset; f _x for traction; mfor car mass; v ₁for there is not the safe speed breakked away; rfor bend radius of curvature; i _h for the transverse slope of road superelevation; φfor lateral adhesion coefficient; gfor acceleration due to gravity.

Obtain the safe speed that vehicle does not occur to break away v ₁, computing formula is:

Wherein, v ₁for there is not the safe speed breakked away, φfor lateral adhesion coefficient, gfor acceleration due to gravity, rfor bend radius of curvature, i _h for the transverse slope of road superelevation.

When vehicle bend travels, the condition not occurring to turn on one's side is that bank moment is not more than aligning torque, considers that the computing formula of road superelevation is:

Wherein, Σ m _ф for the bank moment caused by centrifugal automobile power; Σ mfor the bank moment that the part centrifugal power offset by road superelevation causes; Σ tfor aligning torque; mfor car mass; v ₂for there is not the safe speed of turning on one's side; rfor bend radius of curvature; hfor vehicle centroid height; f _h for the part centrifugal power that road superelevation is offset; gfor acceleration due to gravity; bfor wheelspan; i _h for the transverse slope of road superelevation; φfor lateral adhesion coefficient.

Calculate the safe speed that vehicle does not occur to turn on one's side v ₂, computing formula is:

Wherein, v ₂for there is not the safe speed of turning on one's side, bfor wheelspan, hfor vehicle centroid height, gfor acceleration due to gravity, rfor bend radius of curvature, i _h for the transverse slope of road superelevation, φfor lateral adhesion coefficient.

For ensureing the safety that vehicle bend travels, avoid occurring the dangerous working conditions such as sideslip and rollover, the speed of a motor vehicle must meet above-mentioned two kinds of constraint conditions simultaneously, namely

When above formula gets equal sign, vfor the criticality safety speed of a motor vehicle, v ₁for there is not the safe speed breakked away, v ₂for there is not the safe speed of turning on one's side.

Described safe condition judge module is to current vehicle speed and the criticality safety speed of a motor vehicle vjudge, comprise two kinds of situations:

When current vehicle speed is greater than the criticality safety speed of a motor vehicle vtime, system automatic alarm, alerting signal inputs vehicle-mounted microprocessor, the controller action of maneuvering system automatic control module, and vehicle autobrake is slowed down, and in whole braking deceleration process, if the speed of a motor vehicle is in high-velocity section, desirable deceleration/decel constantly increases; When the speed of a motor vehicle is down to low speed section, for avoiding braking deceleration excessive, desirable deceleration/decel remains unchanged until the speed of a motor vehicle is kept to safe speed, by bend, arranges longitudinal braking deceleration thus , that is:

Wherein: a ₁, a ₂for arithmetic number; 0 ~ t ₁for high-velocity section; t ₁~ t ₂for low speed section.

With reference to Fig. 3, in good time the effect of described system automatic control module regulates and controls travel condition of vehicle, realizes straight way automatic retarding and the maintenance of bend track, comprising: kinematic controller and Dynamics Controller.

The function of described kinematic controller is: when current vehicle speed is greater than the criticality safety speed of a motor vehicle vtime, vehicle enters the straight way autobrake decelerating phase, and detailed process is as follows:

First, vehicle-mounted microprocessor receiving system alerting signal, is taking vehicle as the local coordinate system of reference mijunder, initialization system arbitrary initial error p _e =[ x _e y _e θ _e ] ^t .

Then, according to kinematics control law

Wherein, k ₁, k ₂, k ₃be arithmetic number; lfor the distance between shafts of front and back wheel; v _r for line of reference speed; φ _r for reference front wheel steering angle; v _c for expecting linear velocity; φ _c for expecting front wheel steering angle; p _e =[ x _e y _e θ _e ] ^t for the position and attitude error of vehicle movement under local coordinate system;

Determine bounded control inputs , follow the tracks of the vehicle reference pose under local coordinate system p _r =[ x _r y _r θ _r ] ^t , thus realize time ;

Wherein, pfor the current pose of vehicle; p _r for vehicle reference bit appearance under local coordinate system, with reference to Fig. 4;

Finally, system control signal expects that linear velocity and front wheel steering angle input vehicle-mounted microprocessor, the kinematic controller effect of maneuvering system automatic control module, makes the current running velocity of vehicle vreduce to the criticality safety speed of a motor vehicle now v _c .

The function of described Dynamics Controller is: when current vehicle speed is less than or equal to the criticality safety speed of a motor vehicle vtime, intelligent vehicle enters bend and keeps stage smooth in bend, and detailed process is as follows:

First, vehicle current vehicle speed vrecorded by onboard sensor, expect running velocity with vehicle v _c input vehicle-mounted microprocessor simultaneously.

Then, restrain according to dynamics Controlling

Wherein, α ₁, α ₂>0; β ₁, β ₂>0; mfor car mass; lfor the distance between shafts of front and back wheel; ifor vehicle is around the rotor inertia of vertical axis; vfor the linear velocity of vehicle rear axle center-point; φfor front wheel steering angle; v _c for expecting linear velocity; φ _c for expecting front wheel steering angle; e _v for speed system error; e _φ for front wheel angle systematic error; s _v ( t) be PI type speed sliding-mode surface; s _φ ( t) be PI type front wheel angle sliding-mode surface;

Determine bounded control inputs , follow the tracks of vehicle and expect running velocity , thus realize time ;

Wherein, vfor vehicle real-world operation speed; v _c for running velocity expected by vehicle.

Finally, system control signal driving/braking power and rotating torque input vehicle-mounted microprocessor, the Dynamics Controller effect of maneuvering system automatic control module, make vehicle with current running velocity vsafety bend.

With reference to Fig. 2, a kind of bend preventing side sliding and side turning autocontrol method, specifically comprises the following steps:

Step 1: the path coordinate that bend curvature identification module utilizes vehicle GPS/generalized information system to export estimates road curvature, and utilize vehicle-borne CCD to obtain road image, calculate turning radius by process image, matching road model, obtain the curvature information of curve ahead.

Step 2: be digital signal by the bend radius of curvature convert information of acquisition, after inputting vehicle-mounted microprocessor, safe speed computing module calculates the bend criticality safety speed of a motor vehicle v.

When the centnifugal force produced when vehicle bend travels is less than or equal to road adherence, automobile does not break away; Will consider that road superelevation can offset part centrifugal power, computing formula is simultaneously:

Wherein, ffor the centnifugal force produced during running car; f _h for the part centrifugal power that road superelevation is offset; f _x for traction; mfor car mass; v ₁for there is not the safe speed breakked away; rfor bend radius of curvature; i _h for the transverse slope of road superelevation; φfor lateral adhesion coefficient; gfor acceleration due to gravity;

Obtain the safe speed that vehicle does not occur to break away v ₁, computing formula is:

Wherein, v ₁for there is not the safe speed breakked away, φfor lateral adhesion coefficient, gfor acceleration due to gravity, rfor bend radius of curvature, i _h for the transverse slope of road superelevation.

When vehicle bend travels, the condition not occurring to turn on one's side is that bank moment is not more than aligning torque, considers that the computing formula of road superelevation is:

Wherein, Σ m _ф for the bank moment caused by centrifugal automobile power; Σ mfor the bank moment that the part centrifugal power offset by road superelevation causes; Σ tfor aligning torque; mfor car mass; v ₂for there is not the safe speed of turning on one's side; rfor bend radius of curvature; hfor vehicle centroid height; f _h for the part centrifugal power that road superelevation is offset; gfor acceleration due to gravity; bfor wheelspan; i _h for the transverse slope of road superelevation; φfor lateral adhesion coefficient.

Calculate the safe speed that vehicle does not occur to turn on one's side v ₂, computing formula is:

Wherein, v ₂for there is not the safe speed of turning on one's side, bfor wheelspan, hfor vehicle centroid height, gfor acceleration due to gravity, rfor bend radius of curvature, i _h for the transverse slope of road superelevation, φfor lateral adhesion coefficient.

For ensureing the safety that vehicle bend travels, avoid occurring the dangerous working conditions such as sideslip and rollover, the speed of a motor vehicle must meet above-mentioned two kinds of constraint conditions simultaneously, namely

When above formula gets equal sign, vfor the criticality safety speed of a motor vehicle, v ₁for there is not the safe speed breakked away, v ₂for there is not the safe speed of turning on one's side.

Step 3: serviceable car set sensor records current vehicle speed, in vehicle-mounted microprocessor, safe condition judge module is to current vehicle speed and the criticality safety speed of a motor vehicle vjudge, comprise two kinds of situations:

When current vehicle speed is greater than the criticality safety speed of a motor vehicle vtime, system automatic alarm, alerting signal inputs vehicle-mounted microprocessor, the controller action of maneuvering system automatic control module, and vehicle autobrake is slowed down, and in whole braking deceleration process, if the speed of a motor vehicle is in high-velocity section, desirable deceleration/decel constantly increases; When the speed of a motor vehicle is down to low speed section, for avoiding braking deceleration excessive, desirable deceleration/decel remains unchanged until the speed of a motor vehicle is kept to safe speed, by bend, arranges longitudinal braking deceleration thus , that is:

Wherein: a ₁, a ₂for arithmetic number; 0 ~ t ₁for high-velocity section; t ₁~ t ₂for low speed section.

Step 4: system automatic control module controls intelligent vehicle smoothly by bend, comprises the following steps:

Step 4.1.1: vehicle-mounted microprocessor receiving system alerting signal, is taking vehicle as the local coordinate system of reference mijunder, initialization system arbitrary initial error p _e =[ x _e y _e θ _e ] ^t .

Step 4.1.2: according to kinematics control law

Wherein, k ₁, k ₂, k ₃be arithmetic number; lfor the distance between shafts of front and back wheel; v _r for line of reference speed; φ _r for reference front wheel steering angle; v _c for expecting linear velocity; φ _c for expecting front wheel steering angle; p _e =[ x _e y _e θ _e ] ^t for the position and attitude error of vehicle movement under local coordinate system.

Determine bounded control inputs , follow the tracks of the vehicle reference pose under local coordinate system p _r =[ x _r y _r θ _r ] ^t , thus realize time ;

Wherein, pfor the current pose of vehicle; p _r for vehicle reference bit appearance under local coordinate system.

Step 4.1.3: system control signal expects that linear velocity and front wheel steering angle input vehicle-mounted microprocessor, the kinematic controller effect of maneuvering system automatic control module, makes the current running velocity of vehicle vreduce to the criticality safety speed of a motor vehicle now v _c .

Step 4.2: when current vehicle speed is less than or equal to the criticality safety speed of a motor vehicle vtime, Dynamics Controller controls intelligent vehicle and enters bend and keep stage smooth in bend, comprises following sub-step:

Step 4.2.1: vehicle current vehicle speed vrecorded by onboard sensor, expect running velocity with vehicle v _c input vehicle-mounted microprocessor simultaneously;

Step 4.2.2: restrain according to dynamics Controlling

Wherein, α ₁, α ₂>0; β ₁, β ₂>0; mfor car mass; lfor the distance between shafts of front and back wheel; ifor vehicle is around the rotor inertia of vertical axis; vfor the linear velocity of vehicle rear axle center-point; φfor front wheel steering angle; v _c for expecting linear velocity; φ _c for expecting front wheel steering angle; e _v for speed system error; e _φ for front wheel angle systematic error; s _v ( t) be PI type speed sliding-mode surface; s _φ ( t) be PI type front wheel angle sliding-mode surface.

Determine bounded control inputs , follow the tracks of vehicle and expect running velocity , thus realize time ;

Wherein, vfor vehicle real-world operation speed; v _c for running velocity expected by vehicle.

The foundation of described kinematic controller comprises the following steps:

The first step: set up world coordinate system oxyunder vehicle kinematics model, formula is:

Wherein, lfor the distance between shafts of front and back wheel, θfor edge xthe Current vehicle sense of motion that axle conter clockwise obtains; vfor the linear velocity of vehicle rear axle center-point; p=[ x y θ] ^t for the current pose of vehicle.

Second step: definition local coordinate system mijlower vehicle reference bit appearance p _r =[ x _r y _r θ _r ] ^t with the position and attitude error of vehicle movement p _e =[ x _e y _e θ _e ] ^t ,

Wherein, p _r =[ x _r y _r θ _r ] ^t for vehicle reference bit appearance under local coordinate system; p _e =[ x _e y _e θ _e ] ^t for the position and attitude error of vehicle movement under local coordinate system; θfor edge xthe Current vehicle sense of motion that axle conter clockwise obtains.

Vehicle movement meets nonholonomic constraint, and formula is:

Wherein, lfor the distance between shafts of front and back wheel; θfor edge xthe Current vehicle sense of motion that axle conter clockwise obtains; φfor front wheel steering angle; p=[ x y θ] ^t for the current pose of vehicle.

Differentiate obtains the vehicle position and attitude error differential equation :

Wherein, p _e =[ x _e y _e θ _e ] ^t for the position and attitude error of vehicle movement under local coordinate system; p _r =[ x _r y _r θ _r ] ^t for vehicle reference bit appearance under local coordinate system; lfor the distance between shafts of front and back wheel; φfor front wheel steering angle; φ _r for reference front wheel steering angle; vfor the linear velocity of vehicle rear axle center-point; v _r for line of reference speed.

3rd step: adopt Integrator backstepping method to set up kinematics control module, select suitable kinematics control law , make time , for dynamics Controlling module provides linear velocity and the front wheel steering angle of reference, the process setting up kinematics control module by Integrator backstepping method is as follows:

First, Lyapunov function is selected v ₁;

Wherein: k ₂>0; p _e =[ x _e y _e θ _e ] ^t for the position and attitude error of vehicle movement under local coordinate system.

Then, differentiate v ₁, and by the vehicle position and attitude error differential equation substitute into derived function ;

Wherein, k ₂>0; lfor the distance between shafts of front and back wheel; φfor front wheel steering angle; φ _r for reference front wheel steering angle; vfor the linear velocity of vehicle rear axle center-point; v _r for line of reference speed; p _e =[ x _e y _e θ _e ] ^t for the position and attitude error of vehicle movement under local coordinate system.

Finally, according to select suitable kinematics control law , make time , the stability of system is judged by Lyapunov criterion;

Select

Wherein, k ₁, k ₂, k ₃be arithmetic number; lfor the distance between shafts of front and back wheel; v _r for line of reference speed; φ _r for reference front wheel steering angle; v _c for expecting linear velocity; φ _c for expecting front wheel steering angle; p _e =[ x _e y _e θ _e ] ^t for the position and attitude error of vehicle movement under local coordinate system.

As kinematics control law, due to

Wherein, k ₁, k ₂, k ₃be arithmetic number; lfor the distance between shafts of front and back wheel; vfor the linear velocity of vehicle rear axle center-point; p _e =[ x _e y _e θ _e ] ^t for the position and attitude error of vehicle movement under local coordinate system;

Know according to Lyapunov criterion, in global scope [ x _e y _e θ _e ] ^t bounded and

System has global stability;

Wherein: p _e =[ x _e y _e θ _e ] ^t for the position and attitude error of vehicle movement under local coordinate system.

The foundation of described Dynamics Controller comprises the following steps:

The first step: intelligent vehicle kinetic model is reduced to wheel type machine human occupant dynamic model, that is:

Wherein, τ ₁, τ ₂be respectively driving/braking power and the rotating torque of intelligent vehicle; mfor car mass; ifor vehicle is around the rotor inertia of vertical axis; vfor the linear velocity of vehicle rear axle center-point; wfor vehicle cireular frequency.

According to vehicle kinematics model and kinetic model, derive front wheel steering angle speed formula;

Wherein, τ ₂for the rotating torque of intelligent vehicle; lfor the distance between shafts of front and back wheel; ifor vehicle is around the rotor inertia of vertical axis; φfor front wheel steering angle; vfor the linear velocity of vehicle rear axle center-point.

Second step: adopt the design of PI sliding-mode method to comprise the dynamics Controlling module of equivalent control and switching controls, the output of kinematics control module as with reference to input, export and be , make time , wherein, τ ₁, τ ₂be respectively driving/braking power and the rotating torque of intelligent vehicle;

Implementation procedure is as follows:

First, define system error e=[ e _v e _φ ] ^t , namely

Wherein, e _v for speed system error; e _φ for front wheel angle systematic error; vfor the linear velocity of vehicle rear axle center-point; φfor front wheel steering angle; v _c for expecting linear velocity; φ _c for expecting front wheel steering angle;

Select PI type sliding-mode surface s( t):

Wherein, α ₁, α ₂>0; e _v for speed system error; e _φ for front wheel angle systematic error.

Secondly, differentiate PI type sliding-mode surface, order , obtain system equivalent control rule , formula is:

Wherein, α ₁, α ₂>0; mfor car mass; lfor the distance between shafts of front and back wheel; ifor vehicle is around the rotor inertia of vertical axis; vfor the linear velocity of vehicle rear axle center-point; φfor front wheel steering angle; v _c for expecting linear velocity; φ _c for expecting front wheel steering angle; e _v for speed system error; e _φ for front wheel angle systematic error;

Equivalent control can make state of the system remain on sliding-mode surface, but external interference inevitably exists, and therefore must consider switching controls , designed sliding formwork controls to comprise two parts: equivalent control and switching controls, namely

Namely

Wherein, α ₁, α ₂>0; β ₁, β ₂>0; mfor car mass; lfor the distance between shafts of front and back wheel; ifor vehicle is around the rotor inertia of vertical axis; vfor the linear velocity of vehicle rear axle center-point; φfor front wheel steering angle; v _c for expecting linear velocity; φ _c for expecting front wheel steering angle; e _v for speed system error; e _φ for front wheel angle systematic error; s _v ( t) be PI type speed sliding-mode surface; s _φ ( t) be PI type front wheel angle sliding-mode surface;

Make time .

Again, Lyapunov function is selected v ₂;

Wherein, s( t)=[ s _v ( t) s _φ ( t)] ^t for PI type sliding-mode surface.

Finally, differentiate v ₂, by sliding formwork control law substitute into derived function , judged the stability of system by Lyapunov criterion, formula is:

Wherein, β ₁, β ₂>0; mfor car mass; s _v ( t) be PI type speed sliding-mode surface; s _φ ( t) be PI type front wheel angle sliding-mode surface;

For have , system stability.

Above content is the further description done the present invention in conjunction with optimal technical scheme, can not assert that the concrete enforcement of invention is only limitted to these explanations.Concerning general technical staff of the technical field of the invention, under the prerequisite not departing from design of the present invention, simple deduction and replacement can also be made, all should be considered as protection scope of the present invention.

Claims (2)

1. a bend preventing side sliding and side turning autonomous cruise speed system, it is characterized in that, vehicle-mounted autonomous cruise speed system is adopted to control intelligent vehicle, described vehicle-mounted autonomous cruise speed system comprises: bend curvature identification module, safe speed computing module, safe condition judge module and system automatic control module, and above-mentioned module successively signal connects;

Described bend curvature identification module is used for the curvature information detecting curve ahead in real time, by following process implementation:

Bend curvature identification module utilizes vehicle-borne CCD to obtain road image, by Image semantic classification, adopts Hough transform method matching road model and rebuilds bend lane mark;

The optical axis of pick up camera is parallel to the ground, and due on a highway, surface slope is very little, supposes that on road surface, the Y-coordinate of any point is equal, is the distance H of pick up camera photocentre to ground; For space any point P, there is following relation in its world coordinates (X, Y, Z) and image coordinate (x, y), and it is consistent with global coordinate system initial point namely to move perspective projection center:

$\left\{\begin{array}{c}X=H\frac{x}{y}\\ Y=H\\ Z=f\frac{H}{y}\end{array}\right.$

Wherein, (X, Y, Z) is world coordinates; (x, y) is image coordinate; H is the distance of pick up camera photocentre to ground; F is focal length;

Utilize coordinate transform to change lane mark image, appoint the four groups of points got on the inside lane edge line of space, often organize each three points, its world coordinates is respectively P ₁(X ₁, Y ₁, Z ₁), P ₂(X ₂, Y ₂, Z ₂), P ₃(X ₃, Y ₃, Z ₃), it is substituted into circular arc formula respectively

$R=\sqrt{{(X-a)}^2+{(Z-b)}^2}$

Wherein, (a, b) is the center of circle of circular arc lane mark; R is the radius of curvature of lane mark;

Calculate four suite rate radius value R ₁, R ₂, R ₃and R ₄, respectively compared with the road curvature estimated by the path coordinate utilizing vehicle GPS/generalized information system to export, be reliable curvature information in error allowed band, ask the aviation value of reliable curvature radius to be the radius of curvature of curve ahead;

Described safe speed computing module is for calculating bend criticality safety speed of a motor vehicle v _s, by following process implementation:

Safe speed computing module calculates bend criticality safety speed of a motor vehicle v _s;

When the centnifugal force produced when vehicle bend travels is less than or equal to road adherence, automobile does not break away; Will consider that road superelevation can offset part centrifugal power, computing formula is simultaneously:

Wherein, the centnifugal force produced when F is running car; F _hfor the part centrifugal power that road superelevation is offset; F _xfor traction; M is car mass; v ₁for there is not the safe speed breakked away; R is bend radius of curvature; i _hfor the transverse slope of road superelevation; for lateral adhesion coefficient; G is acceleration due to gravity;

Obtain the safe speed v that vehicle does not occur to break away ₁, computing formula is:

Wherein, v ₁for there is not the safe speed breakked away, for lateral adhesion coefficient, g is acceleration due to gravity, and R is bend radius of curvature, i _hfor the transverse slope of road superelevation;

When vehicle bend travels, the condition not occurring to turn on one's side is that bank moment is not more than aligning torque, considers that the computing formula of road superelevation is:

Wherein, Σ M _фfor the bank moment caused by centrifugal automobile power; The bank moment that Σ M causes for the part centrifugal power offset by road superelevation; Σ T is aligning torque; M is car mass; v ₂for there is not the safe speed of turning on one's side; R is bend radius of curvature; H is vehicle centroid height; F _hfor the part centrifugal power that road superelevation is offset; G is acceleration due to gravity; B is wheelspan; i _hfor the transverse slope of road superelevation; for lateral adhesion coefficient;

Calculate the safe speed v that vehicle does not occur to turn on one's side ₂, computing formula is:

Wherein, v ₂for there is not the safe speed of turning on one's side, b is wheelspan, and h is vehicle centroid height, and g is acceleration due to gravity, and R is bend radius of curvature, i _hfor the transverse slope of road superelevation, for lateral adhesion coefficient;

For ensureing the safety that vehicle bend travels, avoid occurring the dangerous working conditions such as sideslip and rollover, the speed of a motor vehicle must meet above-mentioned two kinds of constraint conditions simultaneously, namely

v _s≤min{v ₁,v ₂}

When above formula gets equal sign, v _sfor the criticality safety speed of a motor vehicle, v ₁for there is not the safe speed breakked away, v ₂for there is not the safe speed of turning on one's side;

Described safe condition judge module is to current vehicle speed and criticality safety speed of a motor vehicle v _sjudge, comprise two kinds of situations:

When current vehicle speed is greater than criticality safety speed of a motor vehicle v _stime, system automatic alarm, alerting signal inputs vehicle-mounted microprocessor, the controller action of maneuvering system automatic control module, and vehicle autobrake is slowed down, and in whole braking deceleration process, if the speed of a motor vehicle is in high-velocity section, desirable deceleration/decel constantly increases; When the speed of a motor vehicle is down to low speed section, for avoiding braking deceleration excessive, desirable deceleration/decel remains unchanged until the speed of a motor vehicle is kept to safe speed, by bend, arranges longitudinal braking deceleration thus that is:

$\stackrel{\&CenterDot;\&CenterDot;}{x}=\left\{\begin{array}{cc}-a_1{t}^2& 0<t\&le;t_1\\ -a_2& t_1<t\&le;t_2\end{array}\right.$

Wherein: a ₁, a ₂for arithmetic number; 0 ~ t ₁for high-velocity section; t ₁~ t ₂for low speed section;

In good time the effect of described system automatic control module regulates and controls travel condition of vehicle, realizes straight way automatic retarding and the maintenance of bend track, comprising: kinematic controller and Dynamics Controller;

The function of described kinematic controller is: when current vehicle speed is greater than criticality safety speed of a motor vehicle v _stime, vehicle enters the straight way autobrake decelerating phase, and detailed process is as follows:

First, vehicle-mounted microprocessor receiving system alerting signal, under the local coordinate system Mij being reference with vehicle, initialization system arbitrary initial error p _e=[x _ey _eθ _e] ^t;

Then, according to kinematics control law

$\left\{\begin{array}{c}{v}_c=k_1{x}_e+v_r\cos {\mathrm{\&theta;}}_e\\ {\mathrm{\&phi;}}_c=\arctan (\frac{v_r}{v_c}\tan {\mathrm{\&phi;}}_r+\frac{k_{2}l{y}_e{v}_r}{v_c}+\frac{k_{3}l\sin {\mathrm{\&theta;}}_e}{v_c})\end{array}\right.$

Wherein, k ₁, k ₂, k ₃be arithmetic number; L is the distance between shafts of front and back wheel; v _rfor line of reference speed; for reference front wheel steering angle; v _cfor expecting linear velocity; for expecting front wheel steering angle; p _e=[x _ey _eθ _e] ^tfor the position and attitude error of vehicle movement under local coordinate system;

Determine bounded control inputs follow the tracks of the vehicle reference pose p under local coordinate system _r=[x _ry _rθ _r] ^t, thus p → p when realizing t → ∞ _r;

Wherein, p is the current pose of vehicle; p _rfor vehicle reference bit appearance under local coordinate system;

Finally, input vehicle-mounted microprocessor, the kinematic controller effect of maneuvering system automatic control module as the expectation linear velocity of system control signal and front wheel steering angle, make the current running velocity u of vehicle reduce to criticality safety speed of a motor vehicle v now _s;

The function of described Dynamics Controller is: when current vehicle speed is less than or equal to criticality safety speed of a motor vehicle v _stime, intelligent vehicle enters bend and keeps stage smooth in bend, and detailed process is as follows:

First, the current running velocity u of vehicle is recorded by onboard sensor, expects running velocity u with vehicle _cinput vehicle-mounted microprocessor simultaneously;

Then, restrain according to dynamics Controlling

$\left\{\begin{array}{c}{\mathrm{\&tau;}}_1=m({\stackrel{\&CenterDot;}{v}}_c+{\mathrm{\&alpha;}}_1{e}_v)+{\mathrm{\&beta;}}_1\mathrm{sgn}\left(s_v\right)\\ {\mathrm{\&tau;}}_2=\frac{I}{l}({\stackrel{\&CenterDot;}{\mathrm{\&phi;}}}_{c}v{\sec }^2\mathrm{\&phi;}+\stackrel{\&CenterDot;}{v}\tan \mathrm{\&phi;}+{\mathrm{\&alpha;}}_2{e}_{\mathrm{\&phi;}}v{\sec }^2\mathrm{\&phi;})+{\mathrm{\&beta;}}_2\mathrm{sgn}\left(s_{\mathrm{\&phi;}}\right)\end{array}\right.$

Wherein, α ₁, α ₂>0; β ₁, β ₂>0; M is car mass; L is the distance between shafts of front and back wheel; I is the rotor inertia of vehicle around vertical axis; V is the linear velocity of vehicle rear axle center-point; for front wheel steering angle; v _cfor expecting linear velocity; for expecting front wheel steering angle; e _vfor speed system error; for front wheel angle systematic error; s _vt () is PI type speed sliding-mode surface; s _φt () is PI type front wheel angle sliding-mode surface;

Determine bounded control inputs τ=[τ ₁τ ₂] ^t, follow the tracks of vehicle and expect running velocity thus u → u when realizing t → ∞ _c;

Wherein, u is the current running velocity of vehicle; u _cfor running velocity expected by vehicle;

Finally, input vehicle-mounted microprocessor, the Dynamics Controller effect of maneuvering system automatic control module as the driving/braking power of system control signal and steering torque, make vehicle with current running velocity u safety bend.

2. a bend preventing side sliding and side turning autocontrol method, specifically comprises the following steps:

Step 1: the path coordinate that bend curvature identification module utilizes vehicle GPS/generalized information system to export estimates road curvature, and utilize vehicle-borne CCD to obtain road image, calculate turning radius by process image, matching road model, obtain the curvature information of curve ahead;

Step 2: be digital signal by the bend radius of curvature convert information of acquisition, after inputting vehicle-mounted microprocessor, safe speed computing module calculates bend criticality safety speed of a motor vehicle v _s;

When the centnifugal force produced when vehicle bend travels is less than or equal to road adherence, automobile does not break away; Will consider that road superelevation can offset part centrifugal power, computing formula is simultaneously:

Wherein, the centnifugal force produced when F is running car; F _hfor the part centrifugal power that road superelevation is offset; F _xfor traction; M is car mass; v ₁for there is not the safe speed breakked away; R is bend radius of curvature; i _hfor the transverse slope of road superelevation; for lateral adhesion coefficient; G is acceleration due to gravity;

Obtain the safe speed v that vehicle does not occur to break away ₁, computing formula is:

Wherein, v ₁for there is not the safe speed breakked away, for lateral adhesion coefficient, g is acceleration due to gravity, and R is bend radius of curvature, i _hfor the transverse slope of road superelevation;

When vehicle bend travels, the condition not occurring to turn on one's side is that bank moment is not more than aligning torque, considers that the computing formula of road superelevation is:

Wherein, Σ M _фfor the bank moment caused by centrifugal automobile power; The bank moment that Σ M causes for the part centrifugal power offset by road superelevation; Σ T is aligning torque; M is car mass; v ₂for there is not the safe speed of turning on one's side; R is bend radius of curvature; H is vehicle centroid height; F _hfor the part centrifugal power that road superelevation is offset; G is acceleration due to gravity; B is wheelspan; i _hfor the transverse slope of road superelevation; for lateral adhesion coefficient;

Calculate the safe speed v that vehicle does not occur to turn on one's side ₂, computing formula is:

Wherein, v ₂for there is not the safe speed of turning on one's side, b is wheelspan, and h is vehicle centroid height, and g is acceleration due to gravity, and R is bend radius of curvature, i _hfor the transverse slope of road superelevation, for lateral adhesion coefficient;

For ensureing the safety that vehicle bend travels, avoid occurring the dangerous working conditions such as sideslip and rollover, the speed of a motor vehicle must meet above-mentioned two kinds of constraint conditions simultaneously, namely

v _s≤min{v ₁,v ₂}

When above formula gets equal sign, v _sfor the criticality safety speed of a motor vehicle, v ₁for there is not the safe speed breakked away, v ₂for there is not the safe speed of turning on one's side;

Step 3: serviceable car set sensor records current vehicle speed, in vehicle-mounted microprocessor, safe condition judge module is to current vehicle speed and criticality safety speed of a motor vehicle v _sjudge, comprise two kinds of situations:

When current vehicle speed is greater than criticality safety speed of a motor vehicle v _stime, system automatic alarm, alerting signal inputs vehicle-mounted microprocessor, the controller action of maneuvering system automatic control module, and vehicle autobrake is slowed down, and in whole braking deceleration process, if the speed of a motor vehicle is in high-velocity section, desirable deceleration/decel constantly increases; When the speed of a motor vehicle is down to low speed section, for avoiding braking deceleration excessive, desirable deceleration/decel remains unchanged until the speed of a motor vehicle is kept to safe speed, by bend, arranges longitudinal braking deceleration thus that is:

$\stackrel{\&CenterDot;\&CenterDot;}{x}=\left\{\begin{array}{cc}-a_1{t}^2& 0<t\&le;t_1\\ -a_2& t_1<t\&le;t_2\end{array}\right.$

Wherein: a ₁, a ₂for arithmetic number; 0 ~ t ₁for high-velocity section; t ₁~ t ₂for low speed section;

Step 4: system automatic control module controls intelligent vehicle smoothly by bend, comprises the following steps:

Step 4.1: when current vehicle speed is greater than criticality safety speed of a motor vehicle v _stime, kinematic controller controls vehicle and enters the straight way autobrake decelerating phase, comprises following sub-step:

Step 4.1.1: vehicle-mounted microprocessor receiving system alerting signal, under the local coordinate system Mij being reference with vehicle, initialization system arbitrary initial error p _e=[x _ey _eθ _e] ^t;

Step 4.1.2: according to kinematics control law

$\left\{\begin{array}{c}{v}_c=k_1{x}_e+v_r\cos {\mathrm{\&theta;}}_e\\ {\mathrm{\&phi;}}_c=\arctan (\frac{v_r}{v_c}\tan {\mathrm{\&phi;}}_r+\frac{k_{2}l{y}_e{v}_r}{v_c}+\frac{k_{3}l\sin {\mathrm{\&theta;}}_e}{v_c})\end{array}\right.$

Wherein, k ₁, k ₂, k ₃be arithmetic number; L is the distance between shafts of front and back wheel; v _rfor line of reference speed; for reference front wheel steering angle; v _cfor expecting linear velocity; for expecting front wheel steering angle; p _e=[x _ey _eθ _e] ^tfor the position and attitude error of vehicle movement under local coordinate system;

Determine bounded control inputs follow the tracks of the vehicle reference pose p under local coordinate system _r=[x _ry _rθ _r] ^t, thus p → p when realizing t → ∞ _r;

Wherein, p is the current pose of vehicle; p _rfor vehicle reference bit appearance under local coordinate system;

Step 4.1.3: input vehicle-mounted microprocessor, the kinematic controller effect of maneuvering system automatic control module as the expectation linear velocity of system control signal and front wheel steering angle, makes the current running velocity u of vehicle reduce to criticality safety speed of a motor vehicle v now _s;

Step 4.2: when current vehicle speed is less than or equal to criticality safety speed of a motor vehicle v _stime, Dynamics Controller controls intelligent vehicle and enters bend and keep stage smooth in bend, comprises following sub-step:

Step 4.2.1: the current running velocity u of vehicle is recorded by onboard sensor, expects running velocity u with vehicle _cinput vehicle-mounted microprocessor simultaneously;

Step 4.2.2: restrain according to dynamics Controlling

$\left\{\begin{array}{c}{\mathrm{\&tau;}}_1=m({\stackrel{\&CenterDot;}{v}}_c+{\mathrm{\&alpha;}}_1{e}_v)+{\mathrm{\&beta;}}_1\mathrm{sgn}\left(s_v\right)\\ {\mathrm{\&tau;}}_2=\frac{I}{l}({\stackrel{\&CenterDot;}{\mathrm{\&phi;}}}_{c}v{\sec }^2\mathrm{\&phi;}+\stackrel{\&CenterDot;}{v}\tan \mathrm{\&phi;}+{\mathrm{\&alpha;}}_2{e}_{\mathrm{\&phi;}}v{\sec }^2\mathrm{\&phi;})+{\mathrm{\&beta;}}_2\mathrm{sgn}\left(s_{\mathrm{\&phi;}}\right)\end{array}\right.$

Wherein, α ₁, α ₂>0; β ₁, β ₂>0; M is car mass; L is the distance between shafts of front and back wheel; I is the rotor inertia of vehicle around vertical axis; V is the linear velocity of vehicle rear axle center-point; for front wheel steering angle; v _cfor expecting linear velocity; for expecting front wheel steering angle; e _vfor speed system error; for front wheel angle systematic error; s _vt () is PI type speed sliding-mode surface; for PI type front wheel angle sliding-mode surface;

Determine bounded control inputs τ=[τ ₁τ ₂] ^t, follow the tracks of vehicle and expect running velocity thus u → u when realizing t → ∞ _c;

Wherein, u is the current running velocity of vehicle; u _cfor running velocity expected by vehicle;

Step 4.2.3: input vehicle-mounted microprocessor, the Dynamics Controller effect of maneuvering system automatic control module as the driving/braking power of system control signal and steering torque, make vehicle with current running velocity u safety bend.