CN111923996B - Multi-mode electro-hydraulic steering system of drive-by-wire chassis and control method - Google Patents

Multi-mode electro-hydraulic steering system of drive-by-wire chassis and control method Download PDF

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Publication number
CN111923996B
CN111923996B CN202010643527.1A CN202010643527A CN111923996B CN 111923996 B CN111923996 B CN 111923996B CN 202010643527 A CN202010643527 A CN 202010643527A CN 111923996 B CN111923996 B CN 111923996B
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steering
motor
mode
steering wheel
rack
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CN111923996A (en
Inventor
周小川
栾众楷
张从余
赵万忠
汪桉旭
高犇
孟丽
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Nanjing Tianhang Intelligent Equipment Research Institute Co ltd
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Nanjing Tianhang Intelligent Equipment Research Institute Co ltd
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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B62LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62DMOTOR VEHICLES; TRAILERS
    • B62D5/00Power-assisted or power-driven steering
    • B62D5/04Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • B62D5/0457Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such
    • B62D5/046Controlling the motor
    • B62D5/0463Controlling the motor for generating assisting torque
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B62LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62DMOTOR VEHICLES; TRAILERS
    • B62D5/00Power-assisted or power-driven steering
    • B62D5/04Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
    • B62D5/0457Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such
    • B62D5/0481Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such monitoring the steering system, e.g. failures
    • B62D5/0484Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such monitoring the steering system, e.g. failures for reaction to failures, e.g. limp home
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B62LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62DMOTOR VEHICLES; TRAILERS
    • B62D5/00Power-assisted or power-driven steering
    • B62D5/06Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
    • B62D5/065Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle characterised by specially adapted means for varying pressurised fluid supply based on need, e.g. on-demand, variable assist
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B62LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62DMOTOR VEHICLES; TRAILERS
    • B62D5/00Power-assisted or power-driven steering
    • B62D5/06Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
    • B62D5/30Safety devices, e.g. alternate emergency power supply or transmission means to ensure steering upon failure of the primary steering means
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B62LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
    • B62DMOTOR VEHICLES; TRAILERS
    • B62D6/00Arrangements for automatically controlling steering depending on driving conditions sensed and responded to, e.g. control circuits

Abstract

The invention discloses a multi-mode electro-hydraulic steering system of a drive-by-wire chassis and a control method, wherein the system comprises the following components: the device comprises a main steering wheel, a main steering column assembly, an auxiliary steering control mechanism, a road sensing assembly, an electric hydraulic power-assisted module, a steering control unit, a distance-measurable infrared sensor, a pressure sensor, an infrared camera, an electromagnetic clutch, a steering tie rod, a steering trapezoid and steering wheels. The method comprises the following steps: inputting a steering wheel corner according to a driving condition; the information processing unit receives, calculates and transmits signals to the working mode decision unit and the steering decision unit; the working mode decision unit obtains a current working mode through comparison, and a signal is input into the steering decision unit; and driving the motor to work and finish steering according to whether an emergency accident occurs or not. The invention can fully exert the advantages of the mixing of the electro-hydraulic pressure and the single-motor electric power assistance, saves labor in the main driving position, improves the reliability of the auxiliary driving position, has the advantages of good energy-saving property, high steering control precision and the like, and reduces the occurrence rate of accidents.

Description

Multi-mode electro-hydraulic steering system of drive-by-wire chassis and control method
Technical Field
The invention relates to the technical field of automobile steering systems, in particular to a multi-mode electro-hydraulic steering system of a drive-by-wire chassis and a control method.
Background
In order to make the motion mode of the vehicle more flexible and to improve the intelligence of the vehicle, the research on the drive-by-wire chassis is a hot spot at present. However, the current drive-by-wire chassis is mainly optimized for the traditional single-steering-wheel vehicle, namely a single-mode steering system; there is no example of a drive-by-wire chassis technology applied thereto for vehicles with multi-mode steering systems. For vehicles such as special engineering vehicles, instructional vehicles and non-road operation vehicles which can be provided with a plurality of steering wheels and steering systems, the wire control chassis can also greatly improve the performance of the vehicles, and the field does not have public reports at present.
For the learner-driven vehicle, in order to play the role that the coach can keep the control of the vehicle and ensure the driving safety when the learner misoperates or operates improperly due to emergency, the mode of a double steering wheel and a double braking device is mostly adopted on the market, and the aim of handling dangerous situations is achieved through timely reaction operation of the coach at a copilot. The garbage recycling vehicle with double steering wheels developed by Volvo automobile group is also provided with a steering wheel at the position of a copilot, and a driver can observe the loading and unloading conditions of garbage behind while driving, so that a better visual field range is obtained, and the operation difficulty of the driver is reduced. In addition, in the case of a road roller having a large vehicle size and a wide vehicle body, it is difficult for the driver to clearly see the surroundings of the vehicle in the cab. Therefore, the traditional one-car one-set steering wheel configuration cannot meet the driving requirements of the rubber-tyred roller. Modern rubber-tyred rollers usually employ two steering wheels to control a steering gear, and the driver can select the left or right steering wheel to control the steering of the vehicle according to the visual field requirement.
For example, chinese patent application No. 201811173388.X discloses a steering control cut-off device for a dual steering wheel of an exercise car, in which a pilot operator presses an auxiliary brake pedal when an emergency occurs, and a main driver training operator cannot operate a main steering wheel. However, such a mechanical structure can only depend on the operation reaction capability of a pilot, and once a fault occurs, an accident can be caused; meanwhile, the double-steering-wheel vehicle on the market generally adopts double-hydraulic power steering or double-electric-control hydraulic power steering, for example, a double-steering-wheel electric control system for an electric forklift disclosed in chinese patent application No. 201821765488.7, a secondary direction is newly added, a high-performance potentiometer is used for controlling a steering signal, but the steering of the whole vehicle is realized only through a steering oil cylinder, and the problems of low precision, high hydraulic energy consumption and the like exist.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a multi-mode electro-hydraulic steering system of a wire-controlled chassis and a control method thereof, so as to overcome the problem of an emergency handling mode with low reliability, namely, the emergency handling mode only through the operation reaction capability of a copilot in the prior art; meanwhile, the hybrid form of the electro-hydraulic pressure and the single motor electric power is adopted, the advantages of the electro-hydraulic pressure and the single motor electric power are fully exerted, the reliability of the auxiliary driving position is improved while the labor of the main driving position is saved, and the hybrid form has the advantages of being good in energy-saving characteristic, high in steering control precision and the like. According to the invention, whether an accident is likely to occur under the current driving condition and the priority between the main operating mechanism and the auxiliary operating mechanism are judged by calculating and comparing the data acquired by the sensor with the database, so that corresponding measures are taken, and the accident occurrence rate is reduced preliminarily.
In order to achieve the purpose, the technical scheme adopted by the invention is as follows:
the invention discloses a multi-mode electro-hydraulic steering system of a drive-by-wire chassis and a control method, comprising the following steps: the device comprises a main steering wheel, a main steering column assembly, an auxiliary steering control mechanism, a road sensing assembly, an electric hydraulic power-assisted module, a steering control unit, a distance-measurable infrared sensor, a pressure sensor, an infrared camera, an electromagnetic clutch, a steering tie rod, a steering trapezoid and steering wheels;
the main steering wheel is connected with a main steering column assembly, and the main steering column assembly comprises: the device comprises a first steering column, a first torque sensor, a corner sensor, a second steering column, a ball screw and a displacement sensor; a first torque sensor and a rotation angle sensor are respectively and fixedly installed on the first steering column, the second steering column is connected to a nut of a ball screw, two ends of a screw rod of the ball screw are coaxially and fixedly connected with a tie rod in an axial direction, and a displacement sensor is fixedly installed on the ball screw and outputs a tie rod displacement signal; the first steering column and the second steering column are connected through an electromagnetic clutch; when the electromagnetic clutch is disconnected, the acting force input by the steering wheel acts on the road feel assembly through the first steering column; when the electromagnetic clutch is closed, the acting force input by the steering wheel is converted into the displacement of the steering tie rod through the first steering column, the electromagnetic clutch, the second steering column and the ball screw;
the sub steering mechanism includes: the steering system comprises an auxiliary steering wheel, a first transmission shaft, a second transmission shaft, a third transmission shaft, a first steering universal joint, a second steering universal joint, a steering execution motor, a second rotation angle sensor, a torque sensor, an electronic power steering gear and a rack and pinion steering gear; the auxiliary steering wheel is connected with a first transmission shaft and then connected to the input end of the electronic power-assisted steering gear through a first universal joint and a second transmission shaft, the output end of the auxiliary steering wheel is connected with the input end of a second universal joint through a third transmission shaft, the output end of the second universal joint is connected with a pinion of a rack-and-pinion steering gear, and a rack end of the rack-and-pinion steering gear is fixed on a steering tie rod; when the auxiliary steering wheel rotates, steering torque is transmitted to the electronic power steering gear through the second transmission shaft after being steered by the first steering shaft and the first universal joint, the electronic power steering gear outputs steering power-assisted torque under the driving of a steering execution motor, and the steering power-assisted torque is transmitted to the rack-and-pinion steering gear after being steered by the third transmission shaft and the second universal joint, so that a rack generates transverse displacement and a steering tie rod is driven to displace;
the second corner sensor and the torque sensor are fixedly arranged on a first transmission shaft of the auxiliary steering control mechanism, connected with the main controller and used for acquiring corner and torque signals of the auxiliary steering wheel;
the road feel assembly includes: the road sensing motor, the third torque sensor and the worm gear; the output end of the road sensing motor is connected with the worm wheel end of a worm gear through a third torque sensor, and the worm end of the worm gear is fixed on the first steering column; torque output by the road feel motor is transmitted to the main steering wheel through the worm gear and the first steering column in sequence to form steering road feel;
the electro-hydraulic power module comprises: the hydraulic control system comprises an oil tank, a hydraulic pump, a first motor, an electromagnetic directional valve, a hydraulic cylinder, a piston rod and a fourth torque sensor; the piston rod is positioned in the hydraulic cylinder, a piston is fixedly arranged on the piston rod, and two ends of the piston rod are fixedly connected with the steering tie rod in a coaxial axial direction; the fourth torque sensor is arranged at the output end of the first motor; hydraulic oil flows to the electromagnetic directional valve from the oil tank and the hydraulic pump in sequence under the action of the first motor, the hydraulic oil flows to two sides of a piston in the hydraulic cylinder through different valve opening degrees of the electromagnetic directional valve, pressure difference is generated on two sides of the piston, so that axial acting force is generated on the piston rod, and the piston rod generates axial displacement motion under the action of the axial force and is transmitted to the tie rod to be converted into displacement motion of the tie rod;
the distance-measurable infrared sensor is fixedly arranged on two sides of a front bumper of the automobile, is connected with the main controller and is used for acquiring a front roadblock direction and a distance signal;
the pressure sensor is fixedly arranged below a passenger seat of the automobile, is connected with the main controller and is used for acquiring a pressure signal at a passenger seat to judge whether a passenger is in the passenger seat;
the infrared camera is fixedly arranged above the automobile copilot, is connected with the main controller and is used for detecting whether a person exists at the copilot under the combined action of the infrared camera and the pressure sensor; when the camera is used for driving a coach in a school, the camera takes a person picture, compares the person picture with a driving school coach system, and judges whether a copilot is a coach or not, so that the working mode is converted;
the steering control unit includes: a main controller and other state units of the vehicle; the input end of the main controller is electrically connected with the sensors and acquires a first torque signal, a second torque signal, a third torque signal, a fourth torque signal, a first rotation angle signal and a second rotation angle signal; the other state units of the vehicle provide a vehicle speed signal and a yaw velocity signal of the current vehicle state for the main controller, provide an obstacle distance and direction signal of a front road condition state, provide a pressure signal of whether a passenger is in a front driving state or not and provide an infrared camera signal; the output end of the main controller is connected with an electromagnetic clutch, a circuit induction motor, an electromagnetic reversing valve, a first motor and a steering execution motor;
an electromagnetic clutch includes: the armature, the driving shaft, the driven shaft, the electromagnet and the friction plate group are arranged in the shell; the driving shaft is axially fixed on the first steering column, the driven shaft is axially fixed on the second steering column, the armature is sleeved on the driving shaft and can axially move, the electromagnet is fixed on the driving shaft, the friction plate group is fixed on the driven shaft, and the electromagnet is positioned between the armature and the friction plate group; the electromagnetic clutch control signal output by the main controller controls the on-off of the coil, and further controls the combination and separation of the electromagnetic clutch.
Furthermore, the steering tie rods are all the same and are fixedly connected with the ball screw of the main steering mechanism, the piston rod and the rack of the rack-and-pinion steering gear of the auxiliary steering mechanism at the same time, and the three do not work at the same time, and the working states are identified, judged and changed through the steering control unit;
further, the main controller comprises an information processing unit, a working mode decision unit, a steering decision unit, a working mode database, a steering execution motor driving unit, a power-assisted motor driving unit, a road sensing motor driving unit, an electromagnetic directional valve driving unit and an electromagnetic clutch driving unit; the information processing unit is electrically connected with the sensors and other state units of the vehicle to acquire signals in real time; the working mode decision unit and the steering decision unit receive input signals of the information processing unit, the working mode database and the steering database, and the steering execution motor driving unit, the power-assisted motor driving unit, the road sensing motor driving unit, the electromagnetic reversing valve driving unit and the electromagnetic clutch driving unit receive the input signals of the steering decision unit and respectively output a steering execution motor control signal, a first motor control signal, a road sensing motor control signal, an electromagnetic reversing valve control signal and an electromagnetic clutch control signal to complete the control of steering action and the switching of different working modes.
The invention discloses a control method of a wire control electro-hydraulic steering system based on double steering wheels, which is based on the system and comprises the following steps:
(1) inputting a steering wheel angle according to the current running condition;
(2) the information processing unit receives the sensor signal, obtains a current vehicle state signal through calculation, and transmits the current vehicle state signal to the working mode decision unit and the steering decision unit;
(3) the working mode decision unit compares the vehicle state signal with a working mode database to obtain a current working mode, and inputs the signal into the steering decision unit; the working modes comprise a main steering wheel single-steering control mechanism mode, a main steering wheel double-steering control mechanism mode, an auxiliary steering wheel double-steering control mechanism mode, an automatic obstacle avoidance mode and a mechanical steering mode;
(4) if no emergency accident occurs and the steering wheel is in a working state, the steering decision unit calculates the working states of the electromagnetic clutch and the electromagnetic reversing valve according to the vehicle state signal, the working mode signal and the steering database, transmits the working states to the electromagnetic clutch driving unit and the electromagnetic reversing valve driving unit, calculates a first steering column torque signal required by the road feel simulation and transmits the first steering column torque signal to the road feel motor driving unit; when the auxiliary steering wheel rotates, if the sensor detects signals and judges that no person accompanies the auxiliary driver, the information processing unit selects to ignore, enters a main steering wheel single-steering control mechanism mode, and a steering execution motor does not work; if the assistant driver is accompanied by a person, entering a dual-steering control mechanism mode of a main steering wheel and an assistant steering wheel, judging whether to accept an input instruction of the assistant steering wheel according to road conditions, if so, outputting an instruction by a steering decision unit to close an electromagnetic clutch and an electromagnetic reversing valve, and starting a steering execution motor to be controlled by the assistant steering wheel;
(5) if an emergency accident occurs and a driver does not make a correct reaction, the automatic obstacle avoidance mode is entered, the steering decision unit calculates the steering direction and a first motor current signal according to the steering database, the electromagnetic directional valve is further driven, and the steering automatic obstacle avoidance mode is taken over by the line control system;
(6) the power-assisted motor driving unit and the steering execution motor driving unit expect the piston displacement x according to the output instruction of the steering decision unitcAnd rack displacement xhCalculating to obtain a first motor driving current and a steering execution motor driving current as control quantities, outputting a first motor control signal and a steering execution motor control signal, and driving the first motor or the steering execution motor to work; the electromagnetic clutch driving unit and the electromagnetic reversing valve driving unit output electromagnetic clutch control signals and electromagnetic reversing valve control signals according to the output instructions of the steering decision unit, and control the working states of the electromagnetic clutch and the electromagnetic reversing valve; the road sensing motor driving unit calculates to obtain a driving current of the road sensing motor by taking the expected first steering column torque as a control quantity according to an output instruction of the steering decision unit, outputs a control signal of the road sensing motor and drives the road sensing motor to work;
(7) electromagnetic torque output by the road feel motor acts on the first steering column, and formed first steering column torque is transmitted to the steering wheel to provide driving road feel for a driver; electromagnetic torque T output by first motornThe hydraulic pump is driven to work, so that pressure difference is generated between two sides of a piston in the hydraulic cylinder to output axial acting force, and the axial acting force is converted into piston displacement xcIs transmitted to the tie rod through the piston rod and converted into the displacement of the tie rod or the torque T output by the steering drive motorepsConverted into rack displacement x of the rack and pinion steering gear through a third transmission shaft and a second universal jointhAnd transmitted to the tie rod to be converted into displacement of the tie rod; the displacement of the steering tie rod is output through a steering trapezoid and a steering wheel to complete steering;
(8) if the first motor fails, the steering decision unit outputs a signal to control the electromagnetic clutch to be closed, a mechanical steering mode is entered, and the input torque of the main steering wheel is converted into the displacement of the tie rod through the first steering column, the electromagnetic clutch, the second steering column and the ball screw, so that steering is completed.
Further, the operation mode and the operation method in the step (3) include:
A. master steering wheel single steering mechanism mode: when no one in the assistant driver follows, the steering execution motor stops running, and the assistant steering wheel is prevented from rotating due to accidents or toppling over of articles;
B. the main steering wheel and the auxiliary steering wheel are in a double-steering control mechanism mode: when a pilot driver rotates the auxiliary steering wheel at the same time, the steering execution motor is selected to work, if the situation that the main steering wheel and the auxiliary steering wheel are input simultaneously is detected, if the situation that the main steering wheel and the auxiliary steering wheel are in safe road conditions is judged, the input of the auxiliary steering wheel is ignored, and the steering execution motor stops working; if the vehicle is in a dangerous road condition and is too close to the barrier, the input of a main steering wheel is ignored, and a steering execution motor starts to work; the main steering wheel is switched into the auxiliary steering wheel to work, the electromagnetic clutch is switched off through the pressure relief electromagnetic reversing valve, and signals are input to the steering execution motor;
C. automatic obstacle avoidance mode: the automatic steering obstacle avoidance of the steer-by-wire system is always in a background monitoring state, and when the vehicle is too close to an obstacle and the main steering wheel and the auxiliary steering wheel have no obstacle avoidance intention or cannot avoid the obstacle in a control mode, the steer-by-wire system takes over steering;
D. when the first motor breaks down, the electromagnetic clutch is closed, and a mechanical steering mode is entered.
Further, the presence or absence of a passenger in the operation mode is detected along with the pressure signal detected by the pressure sensorPfThe magnitude of the pressure detected by the pressure sensor, AfTaking 0.2m as the cross-sectional area of the front passenger seat2,FfThe weight bearing capacity at the copilot is more than or equal to 650N, and the formula shows that when P isfAnd if the power is more than 3250Pa and the existence of the person is detected by the combined infrared camera, the driver is considered to accompany the passenger.
The dynamic model of the main steering system model of the multi-mode steering system and the displacement of the steering transverse tie rod, namely the displacement x of the piston of the hydraulic cylinder in the step (6) are adoptedcThe calculation model is as follows:
wherein, by main steering wheel input signal through first torque sensor, corner sensor detection, main control unit discernment calculation is input to first motor to output torque to the input power and the output power of hydraulic pump respectively are:
the flow model of the electromagnetic directional valve is as follows:
q=KLAKΔpm
in the above formula: pbrFor input of power to hydraulic pumps, PpIs the maximum operating pressure of the pump, qvpIs the internal flow of the hydraulic pump, ηpFor the total efficiency of the hydraulic pump, TnInputting a torque for the first motor; peThe output power of the hydraulic pump is gamma, the gravity of the hydraulic pump for conveying liquid is gamma, and the head of the hydraulic pump is H; q is the fluid flow in the electromagnetic directional valve, KLTo throttle coefficient, AKThe flow area of the orifice or the gap is adopted, and delta p is the pressure difference between the front and the back of the orifice or the gap; etahFor solenoid directional valve efficiency, xcThe displacement of the hydraulic cylinder piston, namely the displacement of the steering tie rod, A is the annular area of the hydraulic cylinder piston, m is an index, and m is more than or equal to 0.5 and less than or equal to 1.
The multi-mode steering system sub-steering system model of the invention and the steering tie rod displacement, i.e. rack and pinion steering gear rack displacement x in the step (6) abovehThe calculation model is as follows:
wherein, the auxiliary steering wheel dynamic model is as follows:
the model from the lower end of the first transmission shaft to the pinion of the rack-and-pinion steering gear of the auxiliary steering mechanism is as follows:
θTB=Kcθe
the pinion power model of the rack and pinion steering gear is as follows:
the rack dynamic model of the rack and pinion steering gear is as follows:
in the above formula: j. the design is a squaresIs the moment of inertia of the secondary steering wheel, thetasFor inputting a steering angle for the auxiliary steering wheel, BsIs the second and third steering shaft damping coefficient, TdriFor the driver input of torque, KsFor the stiffness of the torque sensor, thetaTBIs the lower end corner of the steering shaft; kcFor auxiliary steering gear ratio, thetaeIs the pinion angle of the rack and pinion steering gear; j. the design is a squarezFor the moment of inertia of the steering shaft, TepsInput torque to the steering actuator motor, TwcApplying a torque to the rack and pinion steering gear; m iscFor rack mass of rack-and-pinion steering gear, FzIs the drag on the tie rod, rpcIs the gear radius, x, of a rack and pinion steering gearhIs the rack displacement of a rack and pinion steering gear, i.e. the displacement of a tie rod.
The invention has the following beneficial effects:
1. the invention adopts the steering system structure of the drive-by-wire chassis on the vehicle with a plurality of steering wheels for the first time, adds a plurality of schemes for the steering of the multi-mode steering system vehicle, can carry out the steering priority design and control according to the road condition and the existence of the assistant driver, and the automatic obstacle avoidance mode of the drive-by-wire system monitors and operates in real time at the bottom layer of the system, thereby improving the problem of low reliability that the current double-steering-wheel steering system only adopts a mechanical structure and depends on the operation reaction of the assistant driver to process the emergency situation, and improving the safety and the reliability of the vehicle.
2. The invention adopts the modes of electro-hydraulic hybrid power assistance and electric power assistance respectively in the main steering wheel steering system and the auxiliary steering wheel steering system, and fully exerts the advantages of two systems: the main control mechanism adopts electro-hydraulic hybrid power assistance, the power assistance is large, so that the steering is light, and compared with the traditional hydraulic power assistance, the control is easier, the precision is higher, so that the control of a line control system is easy; the auxiliary control mechanism adopts a single-motor pure electric power assisting mode, the power of the motor on the automobile is limited, so that the power assisting is small, the problem of mistaken touch caused by the existence of the auxiliary steering wheel is solved by utilizing the characteristic from the aspect of reducing the power assisting, the stability of a steering system is improved, meanwhile, the motor has the advantages of being more sensitive and more stable than a mechanical structure in receiving a regulation and control signal instruction of a wire control system, and the reliability of the steering system is improved from the aspect of receiving the response speed of the instruction of the wire control system by the power assisting structure.
3. The mode that whether adopt pressure sensor and infrared camera to jointly detect the copilot and have the personnel to exist and decide whether to start the auxiliary steering wheel is not only economical and reliable, and effectual having handled and being touched by the mistake that brings because there is the auxiliary steering wheel, thereby influence the problem of steering system stability, the existence of infrared camera also provides the possibility for the car networking through face identification copilot whether the operation instruction that whether the copilot will be listened to through the operation instruction that the operation instruction of human face identification copilot is the driver and the year of traveling, simultaneously through the mode that only uses a steering execution motor masterforce, further reduce the influence that the steering execution motor locking fails because of the drive-by-wire system judges the problem emergence in the aspect of reducing the helping hand.
4. The multi-mode steering system enables one automobile to have a plurality of operators, the problems of view blind areas and the like are improved from the aspect that the view angles of the operators are different, the possibility that the plurality of operators can solve the problems in case of emergency is improved, meanwhile, the multi-mode steering system can provide convenience for some special vehicles, such as a dairy cow vehicle, and the left and right steering systems can solve the problem that a worker needs to frequently move the other side of the single steering system when working, and improve the working efficiency; the multi-mode steering system is arranged on the coach car to provide higher operation authority for a copilot coach, improve teaching efficiency and the like.
Drawings
FIG. 1 is a schematic diagram of the system of the present invention;
FIG. 2 is a flow chart of a control method according to the present invention.
Detailed Description
The invention discloses a multi-mode electro-hydraulic steering system of a drive-by-wire chassis and a control method, comprising the following steps: the device comprises a main steering wheel, a main steering column assembly, an auxiliary steering control mechanism, a road sensing assembly, an electric hydraulic power-assisted module, a steering control unit, a distance-measurable infrared sensor, a pressure sensor, an infrared camera, an electromagnetic clutch, a steering tie rod, a steering trapezoid and steering wheels;
the main steering wheel is connected with a main steering column assembly, and the main steering column assembly comprises: the device comprises a first steering column, a first torque sensor, a corner sensor, a second steering column, a ball screw and a displacement sensor; a first torque sensor and a rotation angle sensor are respectively and fixedly installed on the first steering column, the second steering column is connected to a nut of a ball screw, two ends of a screw rod of the ball screw are coaxially and fixedly connected with a tie rod in an axial direction, and a displacement sensor is fixedly installed on the ball screw and outputs a tie rod displacement signal; the first steering column and the second steering column are connected through an electromagnetic clutch; when the electromagnetic clutch is disconnected, the acting force input by the steering wheel acts on the road feel assembly through the first steering column; when the electromagnetic clutch is closed, the acting force input by the steering wheel is converted into the displacement of the steering tie rod through the first steering column, the electromagnetic clutch, the second steering column and the ball screw;
the sub steering mechanism includes: the steering system comprises an auxiliary steering wheel, a first transmission shaft, a second transmission shaft, a third transmission shaft, a first steering universal joint, a second steering universal joint, a steering execution motor, a second rotation angle sensor, a torque sensor, an electronic power steering gear and a rack and pinion steering gear; the auxiliary steering wheel is connected with a first transmission shaft and then connected to the input end of the electronic power-assisted steering gear through a first universal joint and a second transmission shaft, the output end of the auxiliary steering wheel is connected with the input end of a second universal joint through a third transmission shaft, the output end of the second universal joint is connected with a pinion of a rack-and-pinion steering gear, and a rack end of the rack-and-pinion steering gear is fixed on a steering tie rod; when the auxiliary steering wheel rotates, steering torque is transmitted to the electronic power steering gear through the second transmission shaft after being steered by the first steering shaft and the first universal joint, the electronic power steering gear outputs steering power-assisted torque under the driving of a steering execution motor, and the steering power-assisted torque is transmitted to the rack-and-pinion steering gear after being steered by the third transmission shaft and the second universal joint, so that a rack generates transverse displacement and a steering tie rod is driven to displace;
the second corner sensor and the torque sensor are fixedly arranged on a first transmission shaft of the auxiliary steering control mechanism, connected with the main controller and used for acquiring corner and torque signals of the auxiliary steering wheel;
the road feel assembly includes: the road sensing motor, the third torque sensor and the worm gear; the output end of the road sensing motor is connected with the worm wheel end of a worm gear through a third torque sensor, and the worm end of the worm gear is fixed on the first steering column; torque output by the road feel motor is transmitted to the main steering wheel through the worm gear and the first steering column in sequence to form steering road feel;
the electro-hydraulic power module comprises: the hydraulic control system comprises an oil tank, a hydraulic pump, a first motor, an electromagnetic directional valve, a hydraulic cylinder, a piston rod and a fourth torque sensor; the piston rod is positioned in the hydraulic cylinder, a piston is fixedly arranged on the piston rod, and two ends of the piston rod are fixedly connected with the steering tie rod in a coaxial axial direction; the fourth torque sensor is arranged at the output end of the first motor; hydraulic oil flows to the electromagnetic directional valve from the oil tank and the hydraulic pump in sequence under the action of the first motor, the hydraulic oil flows to two sides of a piston in the hydraulic cylinder through different valve opening degrees of the electromagnetic directional valve, pressure difference is generated on two sides of the piston, so that axial acting force is generated on the piston rod, and the piston rod generates axial displacement motion under the action of the axial force and is transmitted to the tie rod to be converted into displacement motion of the tie rod;
the distance-measurable infrared sensor is fixedly arranged on two sides of a front bumper of the automobile, is connected with the main controller and is used for acquiring a front roadblock direction and a distance signal;
the pressure sensor is fixedly arranged below a passenger seat of the automobile, is connected with the main controller and is used for acquiring a pressure signal at a passenger seat to judge whether a passenger is in the passenger seat;
the infrared camera is fixedly arranged above the automobile copilot, is connected with the main controller and is used for detecting whether a person exists at the copilot under the combined action of the infrared camera and the pressure sensor; when the camera is used for driving a coach in a school, the camera takes a person picture, compares the person picture with a driving school coach system, and judges whether a copilot is a coach or not, so that the working mode is converted;
the steering control unit includes: a main controller and other state units of the vehicle; the input end of the main controller is electrically connected with the sensors and acquires a first torque signal, a second torque signal, a third torque signal, a fourth torque signal, a first rotation angle signal and a second rotation angle signal; the other state units of the vehicle provide a vehicle speed signal and a yaw velocity signal of the current vehicle state for the main controller, provide an obstacle distance and direction signal of a front road condition state, provide a pressure signal of whether a passenger is in a front driving state or not and provide an infrared camera signal; the output end of the main controller is connected with an electromagnetic clutch, a circuit induction motor, an electromagnetic reversing valve, a first motor and a steering execution motor;
an electromagnetic clutch includes: the armature, the driving shaft, the driven shaft, the electromagnet and the friction plate group are arranged in the shell; the driving shaft is axially fixed on the first steering column, the driven shaft is axially fixed on the second steering column, the armature is sleeved on the driving shaft and can axially move, the electromagnet is fixed on the driving shaft, the friction plate group is fixed on the driven shaft, and the electromagnet is positioned between the armature and the friction plate group; the electromagnetic clutch control signal output by the main controller controls the on-off of the coil, and further controls the combination and separation of the electromagnetic clutch.
Furthermore, the steering tie rods are all the same and are fixedly connected with the ball screw of the main steering mechanism, the piston rod and the rack of the rack-and-pinion steering gear of the auxiliary steering mechanism at the same time, and the three do not work at the same time, and the working states are identified, judged and changed through the steering control unit;
further, the main controller comprises an information processing unit, a working mode decision unit, a steering decision unit, a working mode database, a steering execution motor driving unit, a power-assisted motor driving unit, a road sensing motor driving unit, an electromagnetic directional valve driving unit and an electromagnetic clutch driving unit; the information processing unit is electrically connected with the sensors and other state units of the vehicle to acquire signals in real time; the working mode decision unit and the steering decision unit receive input signals of the information processing unit, the working mode database and the steering database, and the steering execution motor driving unit, the power-assisted motor driving unit, the road sensing motor driving unit, the electromagnetic reversing valve driving unit and the electromagnetic clutch driving unit receive the input signals of the steering decision unit and respectively output a steering execution motor control signal, a first motor control signal, a road sensing motor control signal, an electromagnetic reversing valve control signal and an electromagnetic clutch control signal to complete the control of steering action and the switching of different working modes.
The invention discloses a control method of a wire control electro-hydraulic steering system based on double steering wheels, which is based on the system and comprises the following steps:
(1) inputting a steering wheel angle according to the current running condition;
(2) the information processing unit receives the sensor signal, obtains a current vehicle state signal through calculation, and transmits the current vehicle state signal to the working mode decision unit and the steering decision unit;
(3) the working mode decision unit compares the vehicle state signal with a working mode database to obtain a current working mode, and inputs the signal into the steering decision unit; the working modes comprise a main steering wheel single-steering control mechanism mode, a main steering wheel double-steering control mechanism mode, an auxiliary steering wheel double-steering control mechanism mode, an automatic obstacle avoidance mode and a mechanical steering mode;
(4) if no emergency accident occurs and the steering wheel is in a working state, the steering decision unit calculates the working states of the electromagnetic clutch and the electromagnetic reversing valve according to the vehicle state signal, the working mode signal and the steering database, transmits the working states to the electromagnetic clutch driving unit and the electromagnetic reversing valve driving unit, calculates a first steering column torque signal required by the road feel simulation and transmits the first steering column torque signal to the road feel motor driving unit; when the auxiliary steering wheel rotates, if the sensor detects signals and judges that no person accompanies the auxiliary driver, the information processing unit selects to ignore, enters a main steering wheel single-steering control mechanism mode, and a steering execution motor does not work; if the assistant driver is accompanied by a person, entering a dual-steering control mechanism mode of a main steering wheel and an assistant steering wheel, judging whether to accept an input instruction of the assistant steering wheel according to road conditions, if so, outputting an instruction by a steering decision unit to close an electromagnetic clutch and an electromagnetic reversing valve, and starting a steering execution motor to be controlled by the assistant steering wheel;
(5) if an emergency accident occurs and a driver does not make a correct reaction, the automatic obstacle avoidance mode is entered, the steering decision unit calculates the steering direction and a first motor current signal according to the steering database, the electromagnetic directional valve is further driven, and the steering automatic obstacle avoidance mode is taken over by the line control system;
(6) the power-assisted motor driving unit and the steering execution motor driving unit expect the piston displacement x according to the output instruction of the steering decision unitcAnd rack displacement xhCalculating to obtain a first motor driving current and a steering execution motor driving current as control quantities, outputting a first motor control signal and a steering execution motor control signal, and driving the first motor or the steering execution motor to work; the electromagnetic clutch driving unit and the electromagnetic reversing valve driving unit output electromagnetic clutch control signals and electromagnetic reversing valve control signals according to the output instructions of the steering decision unit, and control the working states of the electromagnetic clutch and the electromagnetic reversing valve; the road sensing motor driving unit calculates to obtain a driving current of the road sensing motor by taking the expected first steering column torque as a control quantity according to an output instruction of the steering decision unit, outputs a control signal of the road sensing motor and drives the road sensing motor to work;
(7) electromagnetic torque output by the road feel motor acts on the first steering column, and formed first steering column torque is transmitted to the steering wheel to provide driving road feel for a driver; electromagnetic torque T output by first motornThe hydraulic pump is driven to work, so that two pistons in the hydraulic cylinderThe pressure difference generated laterally outputs the axial acting force, and the axial acting force is converted into piston displacement xcIs transmitted to the tie rod through the piston rod and converted into the displacement of the tie rod or the torque T output by the steering drive motorepsConverted into rack displacement x of the rack and pinion steering gear through a third transmission shaft and a second universal jointhAnd transmitted to the tie rod to be converted into displacement of the tie rod; the displacement of the steering tie rod is output through a steering trapezoid and a steering wheel to complete steering;
(8) if the first motor fails, the steering decision unit outputs a signal to control the electromagnetic clutch to be closed, a mechanical steering mode is entered, and the input torque of the main steering wheel is converted into the displacement of the tie rod through the first steering column, the electromagnetic clutch, the second steering column and the ball screw, so that steering is completed.
Further, the operation mode and the operation method in the step (3) include:
A. master steering wheel single steering mechanism mode: when no one in the assistant driver follows, the steering execution motor stops running, and the assistant steering wheel is prevented from rotating due to accidents or toppling over of articles;
B. the main steering wheel and the auxiliary steering wheel are in a double-steering control mechanism mode: when a pilot driver rotates the auxiliary steering wheel at the same time, the steering execution motor is selected to work, if the situation that the main steering wheel and the auxiliary steering wheel are input simultaneously is detected, if the situation that the main steering wheel and the auxiliary steering wheel are in safe road conditions is judged, the input of the auxiliary steering wheel is ignored, and the steering execution motor stops working; if the vehicle is in a dangerous road condition and is too close to the barrier, the input of a main steering wheel is ignored, and a steering execution motor starts to work; the main steering wheel is switched into the auxiliary steering wheel to work, the electromagnetic clutch is switched off through the pressure relief electromagnetic reversing valve, and signals are input to the steering execution motor;
C. automatic obstacle avoidance mode: the automatic steering obstacle avoidance of the steer-by-wire system is always in a background monitoring state, and when the vehicle is too close to an obstacle and the main steering wheel and the auxiliary steering wheel have no obstacle avoidance intention or cannot avoid the obstacle in a control mode, the steer-by-wire system takes over steering;
D. when the first motor breaks down, the electromagnetic clutch is closed, and a mechanical steering mode is entered.
Further, the presence or absence of a passenger in the operation mode is detected along with the pressure signal detected by the pressure sensorPfThe magnitude of the pressure detected by the pressure sensor, AfTaking 0.2m as the cross-sectional area of the front passenger seat2,FfThe weight bearing capacity at the copilot is more than or equal to 650N, and the formula shows that when P isfAnd if the power is more than 3250Pa and the existence of the person is detected by the combined infrared camera, the driver is considered to accompany the passenger.
The dynamic model of the main steering system model of the multi-mode steering system and the displacement of the steering transverse tie rod, namely the displacement x of the piston of the hydraulic cylinder in the step (6) are adoptedcThe calculation model is as follows:
wherein, by main steering wheel input signal through first torque sensor, corner sensor detection, main control unit discernment calculation is input to first motor to output torque to the input power and the output power of hydraulic pump respectively are:
the flow model of the electromagnetic directional valve is as follows:
q=KLAKΔpm
in the above formula: pbrFor input of power to hydraulic pumps, PpIs the maximum operating pressure of the pump, qvpIs the internal flow of the hydraulic pump, ηpFor the total efficiency of the hydraulic pump, TnInputting a torque for the first motor; peThe output power of the hydraulic pump is gamma, the gravity of the hydraulic pump for conveying liquid is gamma, and the head of the hydraulic pump is H; q is the fluid flow in the electromagnetic directional valve, KLTo throttle coefficient, AKThe flow area of the orifice or the gap is adopted, and delta p is the pressure difference between the front and the back of the orifice or the gap; etahFor solenoid directional valve efficiency, xcThe displacement of the hydraulic cylinder piston, namely the displacement of the steering tie rod, A is the annular area of the hydraulic cylinder piston, m is an index, and m is more than or equal to 0.5 and less than or equal to 1.
The multi-mode steering system sub-steering system model of the invention and the steering tie rod displacement, i.e. rack and pinion steering gear rack displacement x in the step (6) abovehThe calculation model is as follows:
wherein, the auxiliary steering wheel dynamic model is as follows:
the model from the lower end of the first transmission shaft to the pinion of the rack-and-pinion steering gear of the auxiliary steering mechanism is as follows:
θTB=Kcθe
the pinion power model of the rack and pinion steering gear is as follows:
the rack dynamic model of the rack and pinion steering gear is as follows:
in the above formula: j. the design is a squaresIs the moment of inertia of the secondary steering wheel, thetasFor inputting a steering angle for the auxiliary steering wheel, BsIs the second and third steering shaft damping coefficient, TdriFor the driver input of torque, KsFor the stiffness of the torque sensor, thetaTBIs the lower end corner of the steering shaft; kcFor auxiliary steering gear ratio, thetaeIs a rack and pinionSteering gear pinion angle; j. the design is a squarezFor the moment of inertia of the steering shaft, TepsInput torque to the steering actuator motor, TwcApplying a torque to the rack and pinion steering gear; m iscFor rack mass of rack-and-pinion steering gear, FzIs the drag on the tie rod, rpcIs the gear radius, x, of a rack and pinion steering gearhIs the rack displacement of a rack and pinion steering gear, i.e. the displacement of a tie rod.
The above description is only an embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can understand that the modifications or substitutions within the technical scope of the present invention are included in the scope of the present invention, and therefore, the scope of the present invention should be subject to the protection scope of the claims.

Claims (5)

1. The control method is characterized in that the multi-mode electro-hydraulic steering system based on the wire-controlled chassis comprises a main steering wheel, a main steering column assembly, an auxiliary steering control mechanism, a road sensing assembly, an electric hydraulic power-assisted module, a steering control unit, a distance-measurable infrared sensor, a pressure sensor, an infrared camera, an electromagnetic clutch, a steering tie rod, a steering trapezoid and steering wheels, and is characterized in that: the main steering wheel is connected with a main steering column assembly, and the main steering column assembly comprises: the device comprises a first steering column, a first torque sensor, a corner sensor, a second steering column, a ball screw and a displacement sensor; a first torque sensor and a rotation angle sensor are respectively and fixedly installed on the first steering column, the second steering column is connected to a nut of a ball screw, two ends of a screw rod of the ball screw are coaxially and fixedly connected with a tie rod in an axial direction, and a displacement sensor is fixedly installed on the ball screw and outputs a tie rod displacement signal; the first steering column and the second steering column are connected through an electromagnetic clutch; the sub steering mechanism includes: the steering system comprises an auxiliary steering wheel, a first transmission shaft, a second transmission shaft, a third transmission shaft, a first steering universal joint, a second steering universal joint, a steering execution motor, a second rotation angle sensor, a torque sensor, an electronic power steering gear and a rack and pinion steering gear; the auxiliary steering wheel is connected with a first transmission shaft and then connected to the input end of the electronic power-assisted steering gear through a first universal joint and a second transmission shaft, the output end of the auxiliary steering wheel is connected with the input end of a second universal joint through a third transmission shaft, the output end of the second universal joint is connected with a pinion of a rack-and-pinion steering gear, and a rack end of the rack-and-pinion steering gear is fixed on a steering tie rod; the second corner sensor and the torque sensor are fixedly arranged on a first transmission shaft of the auxiliary steering control mechanism and connected with the main controller; the road feel assembly includes: the road sensing motor, the third torque sensor and the worm gear; the output end of the road sensing motor is connected with the worm wheel end of a worm gear through a third torque sensor, and the worm end of the worm gear is fixed on the first steering column; the electro-hydraulic power module comprises: the hydraulic control system comprises an oil tank, a hydraulic pump, a first motor, an electromagnetic directional valve, a hydraulic cylinder, a piston rod and a fourth torque sensor; the piston rod is positioned in the hydraulic cylinder, a piston is fixedly arranged on the piston rod, and two ends of the piston rod are fixedly connected with the steering tie rod in a coaxial axial direction; the distance-measuring infrared sensor is fixedly arranged on two sides of the front bumper of the automobile and is connected with the main controller; the pressure sensor is fixedly arranged below a passenger seat of the automobile and is connected with the main controller; the infrared camera is fixedly arranged above the automobile copilot and is connected with the main controller; the steering control unit includes: a main controller and other state units of the vehicle; the input end of the main controller is electrically connected with each sensor; the output end of the main controller is connected with an electromagnetic clutch, a circuit induction motor, an electromagnetic reversing valve, a first motor and a steering execution motor; an electromagnetic clutch includes: the armature, the driving shaft, the driven shaft, the electromagnet and the friction plate group are arranged in the shell; the driving shaft is axially fixed on the first steering column, the driven shaft is axially fixed on the second steering column, the armature is sleeved on the driving shaft and can axially move, the electromagnet is fixed on the driving shaft, the friction plate group is fixed on the driven shaft, and the electromagnet is positioned between the armature and the friction plate group; the main controller comprises an information processing unit, a working mode decision unit, a steering decision unit, a working mode database, a steering execution motor driving unit, a power-assisted motor driving unit, a road sensing motor driving unit, an electromagnetic reversing valve driving unit and an electromagnetic clutch driving unit; the information processing unit is electrically connected with the sensors and other state units of the vehicle; the working mode decision unit and the steering decision unit receive input signals of the information processing unit, the working mode database and the steering database, and the steering execution motor driving unit, the power-assisted motor driving unit, the road sensing motor driving unit, the electromagnetic reversing valve driving unit and the electromagnetic clutch driving unit receive the input signals of the steering decision unit and respectively output a steering execution motor control signal, a first motor control signal, a road sensing motor control signal, an electromagnetic reversing valve control signal and an electromagnetic clutch control signal to complete the control of steering action and the switching of different working modes;
the method comprises the following steps:
(1) inputting a steering wheel angle according to the current running condition;
(2) the information processing unit receives the sensor signal, obtains a current vehicle state signal through calculation, and transmits the current vehicle state signal to the working mode decision unit and the steering decision unit;
(3) the working mode decision unit compares the vehicle state signal with a working mode database to obtain a current working mode, and inputs the signal into the steering decision unit; the working modes comprise a main steering wheel single-steering control mechanism mode, a main steering wheel double-steering control mechanism mode, an auxiliary steering wheel double-steering control mechanism mode, an automatic obstacle avoidance mode and a mechanical steering mode;
(4) when an emergency accident does not occur and the main steering wheel is in a working state, the steering decision unit calculates the working states of the electromagnetic clutch and the electromagnetic reversing valve according to the vehicle state signal, the working mode signal and the steering database, transmits the working states to the electromagnetic clutch driving unit and the electromagnetic reversing valve driving unit, calculates a first steering column torque signal required by road feel simulation, and transmits the first steering column torque signal to the road feel motor driving unit; when the auxiliary steering wheel rotates, the sensor detects signals to judge whether a person accompanies the auxiliary driver, and whether the auxiliary steering wheel input instruction is accepted or not is judged according to road conditions, so that different modes are entered;
(5) when an emergency accident occurs and a driver does not make a correct reaction, the automatic obstacle avoidance mode is entered, the steering decision unit calculates a steering direction and a first motor current signal according to a steering database, drives the electromagnetic directional valve, and takes over the steering automatic obstacle avoidance by a wire control system;
(6) the power-assisted motor driving unit and the steering execution motor driving unit expect the piston displacement x according to the output instruction of the steering decision unitcAnd rack displacement xhCalculating to obtain a first motor driving current and a steering execution motor driving current as control quantities, outputting a first motor control signal and a steering execution motor control signal, and driving the first motor or the steering execution motor to work; the electromagnetic clutch driving unit and the electromagnetic reversing valve driving unit output electromagnetic clutch control signals and electromagnetic reversing valve control signals according to the output instructions of the steering decision unit, and control the working states of the electromagnetic clutch and the electromagnetic reversing valve; the road sensing motor driving unit calculates to obtain a driving current of the road sensing motor by taking the expected first steering column torque as a control quantity according to an output instruction of the steering decision unit, outputs a control signal of the road sensing motor and drives the road sensing motor to work;
(7) electromagnetic torque output by the road feel motor acts on the first steering column, and formed first steering column torque is transmitted to the steering wheel to provide driving road feel for a driver; electromagnetic torque T output by first motornThe hydraulic pump is driven to work, so that pressure difference is generated between two sides of a piston in the hydraulic cylinder to output axial acting force, and the axial acting force is converted into piston displacement xcIs transmitted to the tie rod through the piston rod and converted into the displacement of the tie rod or the torque T output by the steering drive motorepsConverted into rack displacement x of the rack and pinion steering gear through a third transmission shaft and a second universal jointhAnd transmitted to the tie rod to be converted into displacement of the tie rod; the displacement of the steering tie rod is output through a steering trapezoid and a steering wheel to complete steering;
(8) when the first motor breaks down, the steering decision unit outputs a signal to control the electromagnetic clutch to be closed, a mechanical steering mode is entered, and the input torque of the main steering wheel is converted into the displacement of the tie rod through the first steering column, the electromagnetic clutch, the second steering column and the ball screw, so that the steering is completed.
2. The control method of the multi-mode electro-hydraulic steering system for the steer-by-wire chassis according to claim 1, wherein the operation mode and the operation method in the step (3) comprise:
A. master steering wheel single steering mechanism mode: when no one in the assistant driver follows, the steering execution motor stops running, and the assistant steering wheel is prevented from rotating due to accidents or toppling over of articles;
B. the main steering wheel and the auxiliary steering wheel are in a double-steering control mechanism mode: when a pilot driver follows the steering wheel, the steering executing motor is selected to work according to whether the pilot steering wheel rotates;
C. automatic obstacle avoidance mode: the automatic steering obstacle avoidance of the steer-by-wire system is always in a background monitoring state, and when the vehicle is too close to an obstacle and the main steering wheel and the auxiliary steering wheel have no obstacle avoidance intention or cannot avoid the obstacle in a control mode, the steer-by-wire system takes over steering;
D. when the first motor breaks down, the electromagnetic clutch is closed, and a mechanical steering mode is entered.
3. The control method of a multi-mode electro-hydraulic steering system for a steer-by-wire chassis according to claim 1, wherein the presence or absence of a passenger in the operation mode is detected along with a pressure signal detected by a pressure sensorPfThe magnitude of the pressure detected by the pressure sensor, AfTaking 0.2m as the cross-sectional area of the front passenger seat2,FfThe weight bearing capacity at the copilot is more than or equal to 650N, and the formula shows that when P isfAnd if the power is more than 3250Pa and the existence of the person is detected by the combined infrared camera, the driver is considered to accompany the passenger.
4. The control method of the multi-mode electro-hydraulic steering system of the steer-by-wire chassis according to claim 1, wherein the main steering of the multi-mode steering system of the methodDynamic model of system model and piston displacement x in the step (6)cThe calculation model is as follows:
wherein, by main steering wheel input signal through first torque sensor, corner sensor detection, main control unit discernment calculation is input to first motor to output torque to the input power and the output power of hydraulic pump respectively are:
the flow model of the electromagnetic directional valve is as follows:
q=KLAKΔpm
in the above formula: pbrFor input of power to hydraulic pumps, PpIs the maximum operating pressure of the pump, qvpIs the internal flow of the hydraulic pump, ηpFor the total efficiency of the hydraulic pump, TnInputting a torque for the first motor; peThe output power of the hydraulic pump is gamma, the gravity of the hydraulic pump for conveying liquid is gamma, and the head of the hydraulic pump is H; q is the fluid flow in the electromagnetic directional valve, KLTo throttle coefficient, AKThe flow area of the orifice or the gap is adopted, and delta p is the pressure difference between the front and the back of the orifice or the gap; etahFor solenoid directional valve efficiency, xcThe displacement of the hydraulic cylinder piston, namely the displacement of the steering tie rod, A is the annular area of the hydraulic cylinder piston, m is an index, and m is more than or equal to 0.5 and less than or equal to 1.
5. The control method of the multi-mode electro-hydraulic steering system of the steer-by-wire chassis according to claim 1, characterized by comprising a multi-mode steering system auxiliary steering system model of the method and the rack displacement x in the step (6)hThe calculation model is as follows:
wherein, the auxiliary steering wheel dynamic model is as follows:
the model from the lower end of the first transmission shaft to the pinion of the rack-and-pinion steering gear of the auxiliary steering mechanism is as follows:
θTB=Kcθe
the pinion power model of the rack and pinion steering gear is as follows:
the rack dynamic model of the rack and pinion steering gear is as follows:
in the above formula: j. the design is a squaresIs the moment of inertia of the secondary steering wheel, thetasFor inputting a steering angle for the auxiliary steering wheel, BsIs the second and third steering shaft damping coefficient, TdriFor the driver input of torque, KsFor the stiffness of the torque sensor, thetaTBIs the lower end corner of the steering shaft; kcFor auxiliary steering gear ratio, thetaeIs the pinion angle of the rack and pinion steering gear; j. the design is a squarezFor the moment of inertia of the steering shaft, TepsInput torque to the steering actuator motor, TwcApplying a torque to the rack and pinion steering gear; m iscFor rack mass of rack-and-pinion steering gear, FzIs the drag on the tie rod, rpcIs the gear radius, x, of a rack and pinion steering gearhIs the rack displacement of a rack and pinion steering gear, i.e. the displacement of a tie rod.
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