CN209739145U - drive-by-wire steering double-motor system based on driver behavior identification - Google Patents
drive-by-wire steering double-motor system based on driver behavior identification Download PDFInfo
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Abstract
the utility model discloses a wire control steering double-motor system based on driver behavior identification, which comprises an acquisition unit, a central controller, a steering wheel assembly and a front wheel steering assembly; the acquisition unit comprises a plurality of sensors, and the central controller comprises an operation controller and a robustness control and compensation unit; the steering wheel assembly comprises a steering wheel, a steering column, a road sensing motor and a road sensing motor controller; the front wheel steering assembly comprises a corner motor controller, a corner motor, a two-stage speed reducer, a torque motor controller, a torque motor, a speed reducer, a gear rack mechanism and a front wheel; the utility model discloses design has been made to yaw stability control under the control of corner motor open loop to offset various interferences through the suitable compensation torque of torque motor output, thereby guaranteed the stability and the accuracy that the car went, realized car stability, the accuracy, the perfect unity of accuracy nature.
Description
Technical Field
the patent of the utility model relates to an electronic round of car power steering field, especially a steer-by-wire bi-motor system based on driver's action is discerned and stability compensation strategy sways thereof.
background
compared with the traditional steering system, the steer-by-wire system overcomes the defect of fixed transmission ratio of the traditional steering system, and can realize ideal transmission ratio control according to the change of the vehicle speed in the actual driving process of the vehicle. The steer-by-wire variable transmission ratio control not only increases the steering sensitivity of the automobile at low speed, but also increases the driving stability of the automobile in the high-speed driving process.
at present, a steer-by-wire system mainly uses a single-execution-motor steering angle motor, the current of the single-execution-motor is mostly carried out in a closed-loop control mode, and the current of the single-execution-motor is tracked by a front wheel steering angle or a yaw rate of an automobile. The closed-loop control mode is to take the difference value between the actual yaw rate and the ideal yaw rate of the automobile at the previous moment as the input of the motor at the current moment, so that the steering angle motor can only receive the feedback value at the previous moment to perform the action at the next moment, and the reaction prolonging time of the system is prolonged. When the automobile runs straight at a certain speed, especially when steering is just started, because the previous moment of the steering motor is not operated and is defaulted to 0, the default is that the actual yaw rate at the previous moment and the ideal yaw rate at the previous moment are taken as input, however, the real-time yaw rate is obviously not 0 in the actual running process, which causes the first feedback value of the closed-loop system to be greatly different from the actual feedback value, so that instability and vibration of the system are caused, and the large error needs closed-loop feedback at the later moment to be eliminated, so that the time for the system to reach a steady state is prolonged. In addition, the software redundancy mode cannot be used for replacing the single-steering motor under the fault, the steering performance of the automobile can be greatly influenced, and the instability of the automobile can be caused.
at present, the control of double motors is mostly double closed-loop control, a closed-loop control mode of a single motor is still adopted, and the defects of low unavoidable reaction efficiency, large vibration for the first time, long time for a system to reach a steady state and the like of the closed-loop control exist. The research on the yaw stability of the two motors is few, and the automobile is subjected to various interferences, such as lateral wind interference, road surface interference and the like during the driving process, and the interferences have great influence on the driving stability of the automobile, so that the research method is significant for the research strategy of the lateral stability of the two motors. At present, the contents of the steer-by-wire dual-motor system based on driver behavior identification and a yaw stability compensation strategy thereof are not reported yet.
SUMMERY OF THE UTILITY MODEL
to the problem, the utility model provides a steer-by-wire bi-motor system and yaw stability compensation strategy thereof based on driver's action is discerned. The system enables the corner motor to be directly input at the current ideal corner instead of the feedback value at the previous moment through the identification of the behavior of the driver and the establishment of a reverse ideal model, so that the real-time performance of the system is improved.
in order to achieve the above object, the utility model firstly provides a steer-by-wire bi-motor system based on driver's action is discerned, it includes: the device comprises a collecting unit, a central controller, a steering wheel assembly and a front wheel steering assembly;
the acquisition unit includes: a steering wheel angle sensor 4, a steering wheel torque sensor 5, a front wheel steering angle sensor 9, a front wheel torque sensor 12, a vehicle speed sensor 19, a lateral acceleration sensor 20, and a yaw rate sensor 21; the acquisition unit acquires a driver behavior signal, a corner signal of a steering wheel corner sensor, an actual yaw velocity signal, a vehicle speed signal, a corner signal of a corner motor and a torque signal of a torque motor in real time in the driving process of the automobile and transmits the signals to the operation controller 7; the ideal yaw rate calculated by the operation controller 7 through the steering wheel angle signal ideal value and the vehicle speed signal is transmitted to the robustness control and compensation unit 18, and meanwhile, the actual yaw rate signal is transmitted to the robustness control and compensation unit 18; the robustness control and compensation unit 18 calculates corresponding compensation torque according to the transmitted actual yaw rate difference and the ideal yaw rate difference, and transmits the compensation torque to the torque motor controller by considering road surface interference, lateral wind, mechanical friction and the like to drive a corresponding torque motor to compensate;
The central control unit (ECU) comprises an arithmetic controller 7 and a robustness control and compensation unit 18; the robustness control and compensation unit 18 comprises a robustness control unit and a compensation control strategy unit; the steering wheel angle signal acquisition unit receives a driver behavior signal from the acquisition unit and an angle signal of the steering wheel angle sensor to obtain an ideal steering wheel angle signal reflecting the intention of a driver in real time. The operation controller 7 receives the steering wheel corner signal transmitted from the acquisition unit, performs ideal current control on a corner motor according to an ideal corner input through a corner motor controller according to a reverse ideal model, and simultaneously calculates an ideal yaw velocity through the ideal steering wheel corner signal reflecting the intention of a driver in real time and a vehicle speed signal by the operation controller 7 and sends the ideal yaw velocity to the robustness control and compensation unit 18;
the steering wheel assembly comprises a steering wheel 1, a steering column 2, a road sensing motor 3 and a road sensing motor controller 6 which are connected in sequence; the steering wheel assembly feeds back and receives the road feel transmitted by the road feel motor, so that a driver receives the feedback of the real-time road surface condition;
The front wheel steering assembly comprises a corner motor controller 8, a corner motor 10, a double-stage reducer 11, a torque motor controller 16, a torque motor 13, a reducer 14, a gear rack mechanism 15 and a front wheel 17 which are connected in sequence; the corner motor controller 8 receives an ideal input current signal of a corner motor from the torque motor controller 16, enables the corner motor to output a proper corner by acting on the corner motor, acts on a lower-layer steering actuating mechanism, receives a corresponding compensation torque calculated by a robustness control unit and a compensation unit according to a transmitted actual yaw velocity difference and an ideal yaw velocity difference, and transmits the compensation torque to the torque motor controller by considering road surface interference, lateral wind, mechanical friction and the like so as to drive the corresponding torque motor to compensate;
the steering wheel 1 is connected with a road sensing motor 3 and a steering wheel corner sensor 4 through a steering column 2, and a steering wheel torque sensor 5 is arranged on the steering column 2; the road sensing motor controller 6 is connected with the road sensing motor 3 and the steering wheel torque sensor 5 and controls the operation of the road sensing motor 3;
the rack and pinion steering gear 15 is respectively connected with the corner motor 10, the torque motor 13, the double-stage reducer 11 and the reducer 14, and the front wheels 17 are arranged on two sides of the rack and pinion steering gear 15; the front wheel steering angle sensor 9 is mounted on the front wheel 17; the rotation angle sensor 9 and the torque sensor 12 are connected with a Flexray bus, signals of the rotation angle motor controller 8 and signals of the torque motor controller 16 are input into the bus, and then the signals are transmitted to the robustness control and compensation unit 18 through the bus; the corner motor 10 and the double-stage speed reducer 11 are both connected with a corner motor controller 8, the corner motor controller 8 controls the operation of the corner motor 10 and the double-stage speed reducer 11, the torque motor 13 and the speed reducer 14 are both connected with a torque motor controller 16, and the torque motor controller 16 controls the operation of the torque motor 13 and the speed reducer 14;
the lateral acceleration sensor 20 and the yaw rate sensor 21 are both arranged on the wheels 17, and the lateral acceleration sensor 20 and the yaw rate sensor 21 are both respectively connected with the robustness control and compensation unit 18, and input the acquired signals into the robustness control and compensation unit 18;
the output end of the robustness control and compensation unit 18 is respectively connected with the input end of the road induction controller 6 and a Flexay bus, the robustness control and compensation unit 18 receives signals transmitted to a Flexay torque motor controller 12, a corner motor controller 9, a corner sensor 9 and a torque sensor 12 and signals of an arithmetic controller 7, controls the robustness control and compensation strategy, inputs instructions into the Flexery bus, and transmits the instructions to the corner motor controller 8 and a torque motor controller 16 through the Flexery bus to enable a torque motor to act to output torque, thereby compensating the error value of the ideal yaw velocity and the actual yaw velocity of the automobile.
secondly, the utility model discloses still disclose the qualitative compensation strategy of yaw of the wire-controlled steering bi-motor system based on above-mentioned driver action is discerned, this strategy includes:
step 1:
in the running process of the automobile, behavior signals of a driver, a steering angle signal delta sw1 of a steering wheel steering angle sensor, an actual yaw velocity signal omega r, a vehicle speed signal u, a steering angle signal theta of a steering angle motor and a torque signal of a torque motor are collected through a collecting unit and transmitted to an operation controller;
step 2:
The operation controller receives the driver behavior signal from the acquisition unit and the steering wheel angle signal delta sw1 of the steering wheel angle sensor to obtain an ideal steering wheel angle signal delta sw reflecting the intention of a driver in real time; the operation controller obtains an ideal transmission ratio id by synthesizing yaw velocity gain and lateral acceleration gain factors, combines the ideal transmission ratio id with the lower layer dynamic relation of the wire control dual-motor to obtain an ideal function that steering wheel corner ideal current is input into a corner motor, inputs the current value i2 of the corner motor to the corner motor controller by the operation controller, and further transmits the current value to the robustness control unit through the acquisition unit;
The method comprises the following steps:
Step 2.1:
the operation controller identifies and obtains an ideal steering wheel corner delta sw reflecting the intention of a driver through the behavior of the driver;
assuming that the position of the center of mass of the vehicle relative to the ground coordinate system is (X, Y) and the angle between the longitudinal axis of the vehicle and the X axis is phi (vehicle yaw angle), X, Y, and phi can be obtained by:
wherein, X0 and Y0 are the positions of the vehicle at the time when t is 0;
determining the input size of the steering wheel angle according to the displacement error at the preview point and the running angle error of the current position of the automobile:
the displacement error epsilon y at the foresight point of the foresight time Tp is determined by the sum of the lateral displacement Yd of the expected path and the lateral displacement Yd of the vehicle centroid at the current moment;
the steering wheel angle can be expressed as the product of the weighted sum of the vehicle travel displacement error and the direction error and the driver operation delay:
wherein δ sw is an ideal steering wheel angle; k1 and K1 are the driver's compensation gains for displacement error and heading error, respectively; τ d is the delay time;
step 2.2: real-time expression of ideal transmission ratio of automobile
the operation controller obtains the ideal transmission ratio of the steer-by-wire dual-motor automobile by integrating the influence of the yaw velocity gain and the lateral acceleration gain:
Wherein: cwr is the coefficient corresponding to the yaw rate gain, the value range is 3.03-6.25, Cay is the coefficient corresponding to the lateral acceleration gain, the value range is 0.16-0.22;
Step 2.3, substituting the real-time steering wheel delta sw into a reverse ideal input model (5) by the operation controller to obtain an ideal current i2 input by the corner motor, and further transmitting the ideal current i2 to the corner motor controller;
and (5) conversing the ideal input model (5), and performing the derivation flow of the expression as follows:
according to the relationship between the steering wheel angle delta sw, the steering wheel angle delta f and the ideal transmission ratio id, the following results are obtained:
δ＝δ/i (6)
from the relationship between the rack and pinion rotation angle and the steered front wheel rotation angle, it can be:
θ＝δ*G (7)
the relationship between the steering wheel angle and the rack and pinion angle can thus be found:
θ＝δ*G/i (8)
differential equation of motion of the angle motor:
equation of the input torque of the angle motor:
T＝K*i (10)
A dynamic equation of a rack and a pinion in a compensation state of the torque-free motor:
the equation of the rotation angle of the pinion and the input rotation angle of the rotation angle motor is as follows:
θ＝δ/G (12)
can be obtained from the following formulas: ideal current versus rack and pinion angle:
and performing Laplace transformation on the relation between the ideal current and the rotation angle of the rack and the pinion:
taking the state in the steady state as the ideal input of the corner current of the corner motor:
when in steady state, s is 0, it can be obtained from the above formula:
δ f is a front wheel corner, δ sw is a steering wheel corner, BR is a system equivalent damping coefficient, an ideal transmission ratio id, a transmission ratio from a rack pinion corner to a steering front wheel corner, Tm2 is an output torque of a corner motor, Jm2 is a rotational inertia of the corner motor, δ m2 is a corner of the corner motor, Bm2 is a damping of the corner motor, Tg2 is a load torque of the corner motor, Kt is a torque coefficient of the corner motor, i2 is a current of the torque motor, G1 is a reduction ratio of a secondary reducer, JR is a gear-rack system equivalent rotational inertia, BR is a gear-rack system equivalent damping, Ta is a aligning torque borne by a steering wheel, fp is a friction resistance torque, and eta is a transmission efficiency of the system;
step 2.4:
the steering angle motor controller obtains the following signals through an acquisition unit (a front wheel steering angle sensor and a torque sensor): the ideal value delta sw of the steering wheel angle signal, the vehicle speed signal u, the ideal yaw rate and the actual yaw rate signal omega r are transmitted to the robustness control unit;
and step 3:
The yaw rate calculation unit inputs the whole vehicle steering two-degree-of-freedom model according to the real-time vehicle speed u and the front wheel steering angle of the vehicle to obtain the actual yaw rate omega r:
in the formula: m is the mass of the automobile; IZ is the rotational inertia of the automobile around the z axis; k1 and k2 are the cornering stiffness of the front and rear wheels, respectively; δ f is a front wheel corner; a and b are the distances from the front axle and the rear axle to the mass center of the vehicle respectively; u is the vehicle forward speed; ω r is yaw rate; beta is the centroid slip angle;
Meanwhile, the central controller calculates an ideal yaw angular velocity omega r through an ideal steering wheel corner signal delta sw reflecting the intention of a driver in real time and a vehicle speed signal u, and sends the ideal yaw angular velocity omega r to a robustness control and compensation unit;
meanwhile, the operation controller calculates an ideal yaw angular velocity omega r through an ideal steering wheel corner signal delta sw reflecting the intention of a driver in real time and a vehicle speed signal u, and sends the ideal yaw angular velocity omega r to a robustness control and compensation unit;
Ideal yaw rate
stability factor
wherein m is the mass of the automobile, L is the front and rear axle torque of the automobile, K1 is the cornering stiffness of the front axle wheels of the automobile, K2 is the cornering stiffness of the rear axle wheels of the automobile, a is the front axle torque of the automobile, b is the rear axle torque of the automobile, K is the stability factor of the automobile, and u is the longitudinal speed of the automobile;
and 4, step 4:
The robustness control and compensation unit receives an ideal yaw velocity signal ω r from the central controller and a real-time actual vehicle yaw velocity signal ω r for calculation, converts a difference value Δ ω r between the actual yaw velocity and the ideal yaw velocity into a corresponding compensation torque T1, synthesizes a compensation torque T2 formed by road surface interference and a compensation torque T3 formed by system friction, and transmits the total compensation torque Δ T to the compensation control strategy unit for strategy judgment; the stability control factor of the system is considered, and meanwhile, the mu comprehensive robust control is adopted, so that the capacity of the system for resisting external interference is improved;
specifically, Δ T ═ kc ═ Δ I (18)
Δ T is the total compensation torque, Δ I is the compensation current of the torque motor;
the mu comprehensive robust control is realized according to the state space of the yaw angular velocity of the steer-by-wire double-motor, and the method specifically comprises the following steps:
the state variable of the control system is that the input of the system is u ═ Δ I, [ I dr Fyw ] T, the disturbance input of the system is w ═ I dr Fyw ] T, and the output of the system is y ═ r ], then the state space of the steer-by-wire dual-motor yaw angular velocity control is realized as follows:
in the formula (I), the compound is shown in the specification,
wherein θ s2 is a pinion rotation angle under the action of a rotation angle motor, θ s3 is a rotation angle of a pinion under the action of a torque motor, BR is a system equivalent damping coefficient, a transmission ratio G from a rack and pinion rotation angle to a rotation angle of a front steering wheel, I is an ideal input current of the rotation angle motor, Δ I is a compensation current input of the torque motor, Jm2 is a rotational inertia of the rotation angle motor, Jm3 is a rotational inertia of the torque motor, Bm2 is a damping of the rotation angle motor, Bm3 is a damping of the torque motor, Kt is a torque coefficient of the rotation angle motor and the torque motor, G1 is a reduction ratio of a secondary speed reducer, JR is a gear-rack system equivalent rotational inertia, BR is a gear-rack system equivalent damping, fp is a friction resistance moment, and η is 0.99 is a transmission efficiency of the system;
And 5:
the compensation control strategy unit receives the compensation torque from the robustness control unit to carry out compensation control strategy judgment, transmits the judgment result and the total compensation torque delta T suitable for the judgment result to the torque motor, controls the output torque of the torque motor through the torque motor controller so as to compensate the torque folded onto the rack, and drives the wheel to carry out compensation motion, and the compensation control strategy unit comprises the following steps:
the compensation control strategy unit receives the compensation torque from the robustness control unit to carry out compensation control strategy judgment:
When the total compensation torque is a positive value, the torque motor can be controlled to compensate the torque:
the differential equation of motion of the rack is as follows:
In the formula: mrack is the mass of the rack; yrack is the displacement of the rack; rL is the offset of the main pin shaft; KL is the steering linkage stiffness; the Brack is a rack damping coefficient; ffrrack is the friction force between systems, G is the reduction ratio of a double-speed reducer mechanism; tg2 is the output torque of the angle motor; tg3 is the output torque at the moment on the torque motor:
ΔT＝T+T+T (24)
wherein: Δ T is the total compensation torque, T1 is the compensation torque required to compensate for the yaw rate difference, T2 is the compensation torque due to road disturbance, T3 is the compensation torque due to system friction;
when the total compensation torque delta T is a negative value or 0, the torque motor is not controlled to compensate the torque, and the motion differential equation of the rack is as follows:
In the formula: mrack is the mass of the rack; yrack is the displacement of the rack; rL is the offset of the main pin shaft; KL is the steering linkage stiffness; the Brack is a rack damping coefficient; ffrrack is the friction force between systems, G is the reduction ratio of a double-speed reducer mechanism; tg2 is the output torque of the angle motor; tg3 is the output torque of the torque motor;
The torque motor outputs corresponding compensation torque according to a corresponding compensation strategy, and then the gear rack mechanism acts to drive the front wheel to perform corresponding compensation, so that the compensation of the yaw velocity is realized.
the reverse ideal model adopted by the application is an accurate reverse derivation for the system, so that the method is a means for accurately predicting the feedback value. Particularly, when the driver just rotates the steering wheel, the prediction effect of the inverse model is more obvious. When the automobile runs in a straight line, obviously, the yaw velocity of the automobile is not 0, when the automobile starts to turn, the reverse ideal model can predict the real yaw velocity close to the automobile at the moment instead of a simple closed-loop system receiving the value of the yaw velocity 0 at the last moment, so that the first error is reduced, the vibration when the automobile starts to turn is also reduced, and the time for reaching the steady state of the yaw velocity of the automobile is further reduced.
in order to further improve the accuracy of system control, uncertainty in the driving process of the automobile, such as road interference, side wind interference, friction interference and the like, should be considered, and from the aspects of safety and accuracy, the torque motor is adopted to compensate various interferences. The utility model discloses based on reverse ideal input model, the design has been made to yaw stability control under the control of corner motor open loop to offset various interferences through the suitable compensation torque of torque motor output, thereby guaranteed the stability and the accuracy that the car traveled, realized car stability, the accuracy, the perfect unity of accuracy nature.
Compared with the prior art, the utility model provides a steer-by-wire bi-motor system based on driver's action is discerned and yaw stability compensation strategy thereof has following advantage:
1. the corner input reflecting the intention of the driver is obtained by identifying the behavior of the driver, so that on one hand, the corner input speed reflecting the intention of the driver is increased, and the delay link of the input is reduced.
2. on the other hand, the corner motor is directly input in an ideal corner, so that the feedback time generated by tracking the corner of the front wheel is reduced, the delay of a steering system in the steering process is reduced, the steering efficiency in the steering process is greatly improved, and the steering accuracy is improved;
3. although the steering motor is input at an ideal rotation angle, uncertainty in the driving process of the automobile, such as road surface interference, lateral wind interference, friction interference and the like, is considered, from the aspects of safety and accuracy, yaw stability control based on the double execution motors is very important, and the torque motor outputs proper compensation torque through yaw stability control, so that the driving stability and accuracy of the automobile are ensured, and the perfect unification of the stability, accuracy and accuracy of the automobile is realized.
drawings
fig. 1 is a schematic structural diagram of a steer-by-wire dual-motor system of the present invention.
fig. 2 is the utility model discloses a steer-by-wire bi-motor system controlling means schematic diagram based on driver's action is discerned.
fig. 3 is the utility model discloses a steer-by-wire bi-motor system and yaw stability compensation strategy general diagram based on driver's action is discerned.
fig. 4 is a block diagram of the robust control system for the stability of the steer-by-wire dual-motor automobile with compensation function based on the yaw velocity feedback of the utility model.
Detailed Description
In order to facilitate understanding of those skilled in the art, the following further description of the present invention is provided in conjunction with the accompanying drawings, and the embodiments mentioned are not intended to limit the present invention.
In the following examples, the central controller (ECU) is model M7 (in specific implementations, conventional commercially available ECU models such as MT20U, MT20U2, etc. may also be used).
example 1
referring to fig. 1, the utility model discloses a two executive motor system structure arrangement sketch of steer-by-wire mainly includes: the device comprises a collecting unit, a central controller, a steering wheel assembly and a front wheel steering assembly;
the acquisition unit includes: a steering wheel angle sensor 4, a steering wheel torque sensor 5, a front wheel steering angle sensor 9, a front wheel torque sensor 12, a vehicle speed sensor 19, a lateral acceleration sensor 20, and a yaw rate sensor 21;
The central control unit (ECU) comprises an arithmetic controller 7 and a robustness control and compensation unit 18; the robustness control and compensation unit 18 comprises a robustness control unit and a compensation control strategy unit;
the steering wheel assembly comprises a steering wheel 1, a steering column 2, a road sensing motor 3 and a road sensing motor controller 6 which are connected in sequence;
The front wheel steering assembly comprises a corner motor controller 8, a corner motor 10, a double-stage reducer 11, a torque motor controller 16, a torque motor 13, a reducer 14, a gear rack mechanism 15 and a front wheel 17 which are connected in sequence;
The steering wheel 1 is connected with a road sensing motor 3 and a steering wheel corner sensor 4 through a steering column 2, and a steering wheel torque sensor 5 is arranged on the steering column 2; the road sensing motor controller 6 is arranged on the road sensing motor 3, and the road sensing motor controller 6 is connected with the steering wheel torque sensor 5 and controls the operation of the road sensing motor 3;
the rack and pinion steering gear 15 is respectively connected with the corner motor 10, the torque motor 13, the double-stage reducer 11 and the reducer 14, and the front wheels 17 are arranged on two sides of the rack and pinion steering gear 15; the front wheel steering angle sensor 9 is mounted on the front wheel 17; the rotation angle sensor 9 and the torque sensor 12 are connected with a Flexray bus, signals of the rotation angle motor controller 8 and signals of the torque motor controller 16 are input into the bus, and then the signals are transmitted to the robustness control and compensation unit 18 through the bus; the corner motor 10 and the double-stage speed reducer 11 are both connected with a corner motor controller 8, the corner motor controller 8 controls the operation of the corner motor 10 and the double-stage speed reducer 11, the torque motor 13 and the speed reducer 14 are both connected with a torque motor controller 16, and the torque motor controller 16 controls the operation of the torque motor 13 and the speed reducer 14;
the lateral acceleration sensor 20 and the yaw rate sensor 21 are both arranged on the wheels 17, and the lateral acceleration sensor 20 and the yaw rate sensor 21 are both respectively connected with the robustness control and compensation unit 18, and input the acquired signals into the robustness control and compensation unit 18;
the output end of the robustness control and compensation unit 18 is respectively connected with the input end of the road sensing controller 6 and a Flexay bus, the robustness control and compensation unit 18 receives signals transmitted to a Flexary torque motor controller 12, a corner motor controller 9, a corner sensor 9 and a torque sensor 12 and signals of an arithmetic controller 7 to control robustness control and compensation strategies, and inputs instructions to the Flexery bus, and transmits the instructions to the corner motor controller 8 and the torque motor controller 16 through the Flexery bus to enable a torque motor to act to output torque, and a front wheel of the automobile is driven to rotate by a certain angle through a gear rack mechanism, so that the error value of the ideal yaw velocity and the actual yaw velocity of the automobile is compensated.
the embodiment also provides a yaw stability compensation strategy based on the system, as shown in fig. 2-4, which is specifically as follows:
step 1:
in the running process of the automobile, behavior signals of a driver, a steering angle signal delta sw1 of a steering wheel steering angle sensor, an actual yaw velocity signal omega r, a vehicle speed signal u, a steering angle signal theta of a steering angle motor and a torque signal of a torque motor are collected through a collecting unit and transmitted to an operation controller;
step 2:
the operation controller receives the driver behavior signal from the acquisition unit and the steering wheel angle signal delta sw1 of the steering wheel angle sensor to obtain an ideal steering wheel angle signal delta sw reflecting the intention of a driver in real time; the operation controller obtains an ideal transmission ratio id by synthesizing yaw velocity gain and lateral acceleration gain factors, combines the ideal transmission ratio id with the lower layer dynamic relation of the wire control dual-motor to obtain an ideal function that steering wheel corner ideal current is input into a corner motor, inputs the current value i2 of the corner motor to the corner motor controller by the operation controller, and further transmits the current value to the robustness control unit through the acquisition unit;
the step of determining the relationship between the ideal steering wheel angle signal δ sw, the ideal transmission ratio id, and the angle motor ideal current i2 and the steering wheel angle includes:
2.1, the operation controller identifies and obtains an ideal steering wheel corner delta sw reflecting the intention of a driver through the behavior of the driver;
assuming that the position of the center of mass of the vehicle relative to the ground coordinate system is (X, Y) and the angle between the longitudinal axis of the vehicle and the X axis is phi (vehicle yaw angle), X, Y, and phi can be obtained by:
Wherein, X0 and Y0 are the positions of the vehicle at the time when t is 0;
determining the input size of the steering wheel angle according to the displacement error at the preview point and the running angle error of the current position of the automobile:
The displacement error epsilon y at the foresight point of the foresight time Tp is determined by the sum of the lateral displacement Yd of the expected path and the lateral displacement Yd of the vehicle centroid at the current moment;
the steering wheel angle can be expressed as the product of the weighted sum of the vehicle travel displacement error and the direction error and the driver operation delay:
wherein: delta sw is an ideal steering wheel corner; k1 and K2 are the driver's compensation gains for displacement error and heading error, respectively; τ d is the delay time;
2.2 expression of real-time automobile ideal Transmission ratio
the operation controller obtains the ideal transmission ratio of the steer-by-wire dual-motor automobile by integrating the influence of the yaw velocity gain and the lateral acceleration gain:
Wherein: cwr is the coefficient corresponding to the yaw rate gain, the value range is 3.03-6.25, Cay is the coefficient corresponding to the lateral acceleration gain, the value range is 0.16-0.22;
2.3, substituting the real-time steering wheel delta sw into a reverse ideal input model by the operation controller to obtain an ideal current i2 input by the corner motor, and further transmitting the ideal current to the corner motor controller;
the derivation flow of the ideal input model expression is as follows:
Ideal current versus rack and pinion angle:
and performing Laplace transformation on the relation between the ideal current and the rotation angle of the rack and the pinion:
taking the state in the steady state as the ideal input of the corner current of the corner motor:
When in steady state, s is 0, it can be obtained from the above formula:
δ f is a front wheel corner, δ sw is a steering wheel corner, BR is a system equivalent damping coefficient, an ideal transmission ratio id, a transmission ratio from a rack pinion corner to a steering front wheel corner, Tm2 is an output torque of a corner motor, Jm2 is a rotational inertia of the corner motor, δ m2 is a corner of the corner motor, Bm2 is a damping of the corner motor, Tg2 is a load torque of the corner motor, Kt is a torque coefficient of the corner motor, i2 is a current of the torque motor, G1 is a reduction ratio of a secondary reducer, JR is a gear-rack system equivalent rotational inertia, BR is a gear-rack system equivalent damping, Ta is a aligning torque borne by a steering wheel, fp is a friction resistance torque, and eta is a transmission efficiency of the system;
step 2.4:
the steering angle motor controller obtains the following signals through an acquisition unit (a front wheel steering angle sensor and a torque sensor): the ideal value delta sw of the steering wheel angle signal, the vehicle speed signal u, the ideal yaw rate and the actual yaw rate signal omega r are transmitted to the robustness control unit;
and step 3:
the robustness control unit inputs the whole vehicle steering two-degree-of-freedom model according to the real-time vehicle speed u and the front wheel steering angle of the vehicle to obtain the actual yaw rate omega r:
In the formula: m is the mass of the automobile; IZ is the rotational inertia of the automobile around the z axis; k1 and k2 are the cornering stiffness of the front and rear wheels, respectively; δ f is a front wheel corner; a and b are the distances from the front axle and the rear axle to the mass center of the vehicle respectively; u is the vehicle forward speed; ω r is yaw rate; beta is the centroid slip angle;
Meanwhile, the operation controller calculates an ideal yaw angular velocity omega r through an ideal steering wheel corner signal delta sw reflecting the intention of a driver in real time and a vehicle speed signal u, and sends the ideal yaw angular velocity omega r to the robustness control unit;
Ideal yaw rate
stability factor
Wherein m is the mass of the automobile, L is the front and rear axle torque of the automobile, K1 is the cornering stiffness of the front axle wheels of the automobile, K2 is the cornering stiffness of the rear axle wheels of the automobile, a is the front axle torque of the automobile, b is the rear axle torque of the automobile, K is the stability factor of the automobile, and u is the longitudinal speed of the automobile;
and 4, step 4:
the robustness control unit obtains the comprehensive processing of the actual yaw velocity and the ideal yaw velocity, converts the difference value delta omega r between the actual yaw velocity and the ideal yaw velocity into corresponding compensation torque T1, compensation torque T2 formed by road surface interference and compensation torque T3 formed by system friction, considers the system stability control factors, adopts mu comprehensive robustness control at the same time, improves the capability of the system for resisting external interference, obtains a compensation control strategy and transmits the compensation control strategy to the compensation control strategy unit;
wherein Δ T ═ kc Δ I (18)
Δ T is the total compensation torque, Δ I is the compensation current of the torque motor;
in this embodiment, the μ integrated robust control is implemented according to a state space of the steer-by-wire dual-motor yaw rate:
The state variable of the control system is that the input of the system is u ═ Δ I, [ I dr Fyw ] T, the disturbance input of the system is w ═ I dr Fyw ] T, and the output of the system is y ═ r ], then the state space of the steer-by-wire dual-motor yaw angular velocity control is realized as follows:
in the formula (I), the compound is shown in the specification,
wherein θ s2 is a pinion rotation angle under the action of a rotation angle motor, θ s3 is a rotation angle of a pinion under the action of a torque motor, BR is a system equivalent damping coefficient, a transmission ratio G from a rack and pinion rotation angle to a rotation angle of a front steering wheel, I is an ideal input current of the rotation angle motor, Δ I is a compensation current input of the torque motor, Jm2 is a rotational inertia of the rotation angle motor, Jm3 is a rotational inertia of the torque motor, Bm2 is a damping of the rotation angle motor, Bm3 is a damping of the torque motor, Kt is a torque coefficient of the rotation angle motor and the torque motor, G1 is a reduction ratio of a two-stage reducer, JR is a gear-rack system equivalent rotational inertia, BR is a gear-rack system equivalent damping, fp is a friction resistance moment, and η is 0.99 is a transmission efficiency of the system.
the disturbance inputs of the system shown in the figure 4 are an ideal yaw velocity ω r, an input current I of the corner motor A, a road surface disturbance moment dr and a side wind disturbance Fsw. Wd(s) ═ W1W 2W 3 is a disturbance input weighting function matrix, W1, W2 and W3 are weighting functions of I, dr and to Fsw to yaw rate r, respectively; in order to obtain good interference suppression performance of the system, the amplitude-frequency characteristics of W1, W2 and W3 should cover as much as possible the amplitude-frequency characteristics of the transfer function from I, dr and to FSW to yaw rate r, and the transfer function from I, dr and to FSW to yaw rate r can be determined according to the provided state space;
And 5:
the compensation control strategy unit receives the compensation torque from the robustness control unit to carry out compensation control strategy judgment, transmits the judgment result and the total compensation torque delta T suitable for the judgment result to the torque motor, controls the output torque of the torque motor through the torque motor controller so as to compensate the torque folded on the rack, and drives the wheels to carry out compensation motion, and the compensation control strategy unit comprises the following steps:
the compensation control strategy unit receives the compensation torque from the robustness control unit to carry out compensation control strategy judgment:
when the total compensation torque is a positive value, the torque motor can be controlled to compensate the torque:
the differential equation of motion of the rack is as follows:
In the formula: mrack is the mass of the rack; yrack is the displacement of the rack; rL is the offset of the main pin shaft; KL is the steering linkage stiffness; the Brack is a rack damping coefficient; ffrrack is the friction force between systems, G is the reduction ratio of a double-speed reducer mechanism; tg2 is the output torque of the angle motor; tg3 is the output torque at the moment on the torque motor:
ΔT＝T+T+T
wherein: Δ T is the total compensation torque, T1 is the compensation torque required to compensate for the yaw rate difference, T2 is the compensation torque due to road disturbance, T3 is the compensation torque due to system friction;
when the total compensation torque delta T is a negative value or 0, the torque motor is not controlled to compensate the torque, and the motion differential equation of the rack is as follows:
In the formula: mrack is the mass of the rack; yrack is the displacement of the rack; rL is the offset of the main pin shaft; KL is the steering linkage stiffness; the Brack is a rack damping coefficient; ffrrack is the friction force between systems, G is the reduction ratio of a double-speed reducer mechanism; tg2 is the output torque of the angle motor; tg3 is the output torque of the torque motor.
the torque motor outputs corresponding compensation torque according to a corresponding compensation strategy, and then the gear rack mechanism acts to drive the front wheel to perform corresponding compensation, so that the compensation of the yaw velocity is realized.
The utility model discloses a specific application way is many, above only the preferred embodiment of the utility model discloses a should point out, to ordinary technical personnel in this technical field, no longer breaks away from the utility model discloses under the prerequisite of patent principle, can also make a plurality of improvements, these improvements also should be regarded as the utility model discloses a protection scope.
Claims (1)
1. a steer-by-wire dual motor system based on driver behavior recognition, the system comprising: the device comprises a collecting unit, a central controller, a steering wheel assembly and a front wheel steering assembly;
the acquisition unit includes: a steering wheel rotation angle sensor (4), a steering wheel torque sensor (5), a front wheel rotation angle sensor (9), a torque sensor (12), a vehicle speed sensor (19) and a lateral acceleration sensor
(20) and a yaw-rate sensor (21);
The central controller comprises an arithmetic controller (7) and a robustness control and compensation unit (18); the robustness control and compensation unit (18) comprises a robustness control unit and a compensation control strategy unit;
The steering wheel assembly comprises a steering wheel (1), a steering column (2), a road sensing motor (3) and a road sensing motor controller (6) which are connected in sequence;
the front wheel steering assembly comprises a corner motor controller (8), a corner motor (10), a double-stage speed reducer (11), a torque motor controller (16), a torque motor (13), a speed reducer (14), a gear-rack mechanism (15) and a front wheel (17) which are connected in sequence;
The steering wheel (1) is connected with a road sensing motor (3) and a steering wheel corner sensor (4) through a steering column (2), and a steering wheel torque sensor (5) is arranged on the steering column (2); the road sensing motor controller (6) is arranged on the road sensing motor (3) and is connected with the steering wheel torque sensor (5);
the gear rack mechanism (15) is respectively connected with the corner motor (10), the torque motor (13) and the double-stage reducer
(11) the front wheels (17) are arranged on two sides of the gear rack mechanism (15); the front wheel steering angle sensor (9) is arranged on a front wheel (17); the front wheel steering angle sensor (9) and the torque sensor (12) are connected with a bus, signals of the steering angle motor controller (8) and the torque motor controller (16) are input into the bus, and then the signals are transmitted into the robustness control and compensation unit (18) through the bus; the corner motor (10) and the double-stage speed reducer (11) are both connected with a corner motor controller (8), and the torque motor (13) and the speed reducer (14) are both connected with a torque motor controller (16);
the lateral acceleration sensor (20) and the yaw rate sensor (21) are both arranged on the front wheel (17), and the lateral acceleration sensor (20) and the yaw rate sensor (21) are both respectively connected with the robustness control and compensation unit (18);
a robust control and compensation unit (18) and a road sensing motor controller (6) are respectively connected with the bus, and the robust control and compensation unit (18) is connected with a torque motor controller (16), a corner motor controller (8), a front wheel corner sensor (9), a torque sensor (12), an operation controller (7) and a corner motor controller
(8) and a torque motor controller (16) are respectively connected.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109664938A (en) * | 2018-12-29 | 2019-04-23 | 南京航空航天大学 | Steering-by-wire dual motors system and its Yaw stability compensation policy based on driving behavior identification |
| CN112937545A (en) * | 2021-03-18 | 2021-06-11 | 江苏大学 | Automatic driving automobile steering control system and method for coping with driver interference |
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2018
- 2018-12-29 CN CN201822255564.6U patent/CN209739145U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109664938A (en) * | 2018-12-29 | 2019-04-23 | 南京航空航天大学 | Steering-by-wire dual motors system and its Yaw stability compensation policy based on driving behavior identification |
| CN109664938B (en) * | 2018-12-29 | 2023-12-01 | 南京航空航天大学 | Drive-by-wire steering double-motor system based on driver behavior identification and yaw stability compensation strategy thereof |
| CN112937545A (en) * | 2021-03-18 | 2021-06-11 | 江苏大学 | Automatic driving automobile steering control system and method for coping with driver interference |
| CN112937545B (en) * | 2021-03-18 | 2024-07-12 | 江苏大学 | Automatic driving automobile steering control system and method for coping with driver interference |
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