Super virtual track train and electric steering control system, control method thereof

Abstract

The application discloses a super virtual track train and an electric steering control system and control method thereof, the control method comprising: acquiring a steering angle of a first axle, a train running speed and a running direction; calculating a target steering angle of a rear axle of a first car and target steering angles of front and rear axles of an ith car according to the steering angle of the first axle, the train running speed and the running direction; generating steering control instructions of each axle according to the target steering angles of the front and rear axles of each car, driving corresponding steering actuators to move according to the steering control instructions, and realizing electric active steering control of each car. According to the target steering angle, the application realizes autonomous steering control of the corresponding axle, enables each car to run along a fixed path, reduces the driving burden of the driver, enables the vehicle to realize precise virtual track following control, and obtains a faster response speed than hydraulic steering.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of rail transit, and particularly relates to a super virtual rail train and an electric drive-by-wire active steering control system and control method thereof. BACKGROUND

[0002] The multi-axle heavy-load super virtual rail train formed by multiple coupled sections has the characteristics of large capacity, low cost, intelligence and 100% low floor, and gradually becomes the mainstream development product of future green and intelligent transportation tools.

[0003] The super virtual rail train with multi-axle heavy load is formed by coupling multiple sections of vehicles, and the inside of the vehicle is designed according to the standard of rail transit, has the characteristics of long vehicle body, multiple axles and heavy axle, and the driver has the problems of large road occupation width, poor flexibility, late steering and large error during driving the super virtual rail train to turn, and the train is prone to spin, deviate from the lane and cause traffic accidents.

[0004] At present, the train realizes single-axle active steering by using a hydraulic steering system, but the pipeline and equipment of the hydraulic actuator are complex, and there is a risk of hydraulic pipeline oil leakage, which brings difficulties to use and maintenance. SUMMARY

[0005] The purpose of the present application is to provide a super virtual rail train and an electric steering control system and control method thereof to solve the problems of complex pipeline and equipment of the traditional hydraulic steering system, which is not easy to arrange on the vehicle bottom, has the risk of hydraulic pipeline oil leakage, increases the pollution to the environment, and the steering control is not timely and has large error.

[0006] The present application is to solve the above technical problems by the following technical solutions: an electric steering control system of a super virtual rail train, comprising a steering controller and an electric steering control device configured for each axle of each section of the vehicle, each electric steering control device comprising:

[0007] A steering linkage mechanism is arranged on the vehicle body chassis and connected with the corresponding axle, and is used to drive the rotation of the wheels on the axle under the drive of the steering actuator;

[0008] An angle sensor is arranged at both ends of the vehicle body chassis and the steering linkage mechanism, and is used to collect the steering angle of the corresponding axle;

[0009] A steering actuator is arranged on the vehicle body chassis and connected with the steering linkage mechanism, and is used to act according to the steering action instruction;

[0010] The steering control unit receives a steering angle corresponding to an axle and sends the steering angle to a steering controller; receives a steering control instruction corresponding to an axle and sends a steering action instruction to the steering actuator according to the steering control instruction;

[0011] The steering controller obtains a steering angle of a first axle, a train running speed and a running direction; calculates a target steering angle of a rear axle of a first car and target steering angles of front and rear axles of an i-th car according to the steering angle of the first axle, the train running speed and the running direction; and generates a steering control instruction of each axle according to the target steering angles of the front and rear axles of each car; wherein the first axle refers to a front axle of the first car and is directly controlled by a steering wheel, i = 2, 3, …, n, n is the number of cars of the train, and the specific formula of the target steering angle is:

[0012]

[0013] wherein γ 2i-1 is a target steering angle of a front axle of an i-th car, γ 2i is a target steering angle of a rear axle of the i-th car, when i = 1, γ1 is a steering angle of the first axle, and γ2 is a target steering angle of a rear axle of the first car; R gi is a distance from a hinge point G i between the i-th car and the i-1-th car to a turning instantaneous center M; A 2i-1 is a front wheel center of mass of the i-th car; R 2i-1 is a distance from the front wheel center of mass A 2i-1 of the i-th car to the turning instantaneous center M; is a front wheel cornering stiffness of the i-th car, is a rear wheel cornering stiffness of the i-th car, β is a cornering angle of a vehicle center of mass, v x is a component of a train running speed in an x direction, r is a yaw rate of the vehicle center of mass, is a length of a front axle of the i-th car from the vehicle center of mass, is a length of a rear axle of the i-th car from the vehicle center of mass, m is a total vehicle mass, a y is a vehicle lateral acceleration.

[0014] Further, the steering linkage mechanism is a trapezoidal steering linkage mechanism, which comprises a first steering rocker, a first connecting rod, an I-shaped arm, a cross rod, an L-shaped arm, a second connecting rod and a second steering rocker connected in sequence; the I-shaped arm and the L-shaped arm are arranged on the vehicle body frame; the first steering rocker and the second steering rocker are respectively connected with two ends of a corresponding axle; and the L-shaped arm is connected with the steering actuator.

[0015] Further, the steering linkage mechanism is connected with the steering actuator through a steering longitudinal rod.

[0016] Further, the steering actuator comprises a reduction gear box and a steering motor.

[0017] Further, mechanical stops and limit switches are arranged on both sides of the vehicle body frame, and the limit switches are located on the side away from the mechanical stops.

[0018] Further, each electric steering control device further comprises a displacement sensor for detecting the lateral displacement of the steering linkage mechanism and transmitting the lateral displacement to the steering control unit.

[0019] The steering control unit controls the steering actuator according to the lateral displacement to achieve accurate control of the lateral displacement.

[0020] Based on the same inventive concept, the application also provides an electric steering control method for super virtual track trains, comprising the following steps:

[0021] Obtaining the steering angle of the first axle, the train running speed and the running direction, wherein the first axle refers to the front axle of the first car and is directly controlled by the steering wheel;

[0022] Calculating the target steering angle of the rear axle of the first car and the target steering angles of the front and rear axles of the i-th car according to the steering angle of the first axle, the train running speed and the running direction, wherein i=2, 3, …, n, n is the number of cars, and the specific formula is:

[0023]

[0024] Wherein, γ 2i-1 is the target steering angle of the front axle of the i-th car, γ 2i is the target steering angle of the rear axle of the i-th car, when i=1, γ1 is the steering angle of the first axle, and γ2 is the target steering angle of the rear axle of the first car; R gi is the distance from the hinge point G i between the i-th car and the i-1-th car to the instantaneous center of rotation M; A 2i-1 is the front wheel center of mass of the i-th car; R 2i-1 is the front wheel center of mass A 2i-1 of the i-th car to the instantaneous center of rotation M; is the front wheel cornering stiffness of the i-th car, is the rear wheel cornering stiffness of the i-th car, β is the cornering angle of the vehicle center of mass, v x is the component of the train running speed in the x direction, r is the yaw rate of the vehicle center of mass, is the length of the front axle of the i-th car from the vehicle center of mass, L i is the length from the rear axle of the ith section to the center of mass of the vehicle, m is the mass of the vehicle, a y is the lateral acceleration of the vehicle;

[0025] The steering control instructions of each axle are generated according to the target steering angles of the front and rear axles of each section, and the corresponding steering actuators are driven to move according to the steering control instructions, so as to realize the electric active steering control of each section.

[0026] Further, before the corresponding steering actuators are driven to move according to the steering control instructions, the control method further includes the step of judging whether the steering limit is reached according to the target steering angle of the axle, and the specific implementation process is as follows:

[0027] If the target steering angle of the axle is ≥ γ 10 or the target steering angle of the axle is ≤ - γ 10 , a steering warning is sent to the driver, and it is judged whether the limit switch signal is received; if the limit switch signal is received, an alarm is sent, and an emergency braking operation is performed; if the limit switch signal is not received, the corresponding steering actuator is driven to move;

[0028] If - γ 10 < the target steering angle of the axle < γ 10 , the corresponding steering actuator is driven to move; wherein γ 10 is a soft limit threshold.

[0029] Further, the specific implementation process of generating the steering control instructions of each axle according to the target steering angles of the front and rear axles of each section is as follows:

[0030] The real-time steering angle of the axle is obtained;

[0031] The steering deviation of the real-time steering angle and the target steering angle of the axle is calculated;

[0032] The steering control instructions are generated according to the steering deviation based on the PID control mode.

[0033] Based on the same inventive concept, the application also provides a super virtual track train comprising the electric steering control system as described above.

[0034] Advantages

[0035] Compared with the prior art, the application has the following advantages:

[0036] The super virtual track train and the electric steering control system, control method thereof provided by the application are characterized in that each axle is provided with an electric steering control device, the target steering angle of each axle of each car is calculated according to the steering angle of the steering wheel, and then the autonomous steering control of the corresponding axle is realized according to the target steering angle, so that each car can run along a fixed path, the driving burden of the driver is reduced, the vehicle can realize precise virtual track following control, and a faster response speed than the hydraulic steering is obtained.

[0037] Compared with the traditional hydraulic steering system, the complex pipeline and equipment are reduced, the whole steering control system is simple and clear, and the vehicle bottom is easy to arrange; the steering wheel action is completely decoupled from the steering of each axle by adopting the electric steering control system, so that the control of each axle is more accurate; the response time of the system is shortened, and the steering control precision is improved; there is no risk of hydraulic pipeline oil leakage, the environmental pollution is reduced, and the development idea of green and intelligent traffic is met. BRIEF DESCRIPTION OF DRAWINGS

[0038] In order to more clearly illustrate the technical solutions of the application, the drawings needed in the embodiment description will be briefly introduced below. Obviously, the drawings in the following description are only one embodiment of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0039] Figure 1 It is a structure schematic diagram of the electric steering control system in the embodiment of the application.

[0040] Figure 2 It is a structure schematic diagram of the steering connecting rod mechanism in the embodiment of the application.

[0041] Figure 3 It is a flow chart of the electric steering control method of the super virtual track train in the embodiment of the application.

[0042] Figure 4 It is a dynamics model of a single car in the embodiment of the application.

[0043] Figure 5 It is a train model of two cars and four axles in the embodiment of the application.

[0044] Figure 6 It is a three-level positive and negative limit diagram in the embodiment of the application.

[0045] Wherein, 1 - axle, 2 - steering linkage, 21 - first steering arm, 22 - first connecting rod, 23 - I-shaped arm, 24 - cross rod, 25 - L-shaped arm, 26 - second connecting rod, 27 - second steering arm, 3 - displacement sensor, 4 - angle sensor, 5 - steering actuator, 51 - reduction gear box, 52 - steering motor, 6 - steering drag link, 7 - steering controller, 8 - steering control unit, 9 - mechanical stop, 10 - limit switch. DETAILED DESCRIPTION

[0046] The technical solutions in the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0047] The technical solutions of the present application will be described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes can not be described in some embodiments.

[0048] The super virtual track train is composed of multiple carriages, and each axle of each carriage is configured with an electric steering control device. The whole train shares a steering controller 7 (i.e. STCU), as shown in Figure 1 Each electric steering control device includes a steering linkage 2, an angle sensor 4, a steering actuator 5, and a steering control unit 8 (i.e. ECU). The steering linkage 2 is arranged on the vehicle body frame and connected with the corresponding axle and the steering actuator 5. One end of the angle sensor 4 is arranged on the vehicle body frame, and the other end is arranged on the steering linkage 2. The steering actuator 5 is arranged on the vehicle body frame.

[0049] The axle is connected with the vehicle body frame, and the two ends of the axle are installed with wheels to bear the weight of the vehicle body. The axle serves as the final execution mechanism of steering control, and drives the left and right deflection of the wheels at both ends through the steering linkage 2. In one specific embodiment of the present application, as shown in Figure 1 and 2As shown, the steering linkage 2 is a trapezoidal steering linkage 2, which comprises a first steering rocker 21, a first connecting rod 22, an I-shaped arm 23, a cross rod 24, an L-shaped arm 25, a second connecting rod 26 and a second steering rocker 27 connected in sequence; the I-shaped arm 23 and the L-shaped arm 25 are arranged on the vehicle body frame; the first steering rocker 21 and the second steering rocker 27 are respectively connected with both ends of the axle; the L-shaped arm 25 is connected with the steering actuator 5 through the steering longitudinal rod 6. The L-shaped arm 25 is connected with the steering longitudinal rod 6 through a spherical hinge, which can eliminate vibration. When the steering actuator 5 generates a steering power, the first steering rocker 21 and the second steering rocker 27 are driven to move through the cross rod 24, the I-shaped arm 23 and the L-shaped arm 25, the steering power is transmitted to both ends of the axle, and acts on the wheels to realize the left and right deflection of the wheels. The steering longitudinal rod 6 is used to transmit the steering power and displacement output by the steering actuator 5 to the steering linkage 2, and drive the wheels to rotate.

[0050] The angle sensor 4 has two, one end of one of the angle sensors 4 is arranged on the first connecting rod 22, and the other end is arranged on the vehicle body frame; one end of the other angle sensor 4 is arranged on the second connecting rod 26, and the other end is arranged on the vehicle body frame. The movement of the first connecting rod 22 or the second connecting rod 26 drives the angle sensor 4 to rotate, generates a measurement value, and realizes the measurement of the steering angle. The angle sensor 4 measures the steering angle of each axle, and sends the measured steering angle to the steering controller 7 through the steering control unit 8.

[0051] In the embodiment, each car is numbered, the first car is the car where the driver's cab is located, and the other cars are sequentially the second car, the third car, …, the i-th car, …, and the n-th car, where i = 2, 3, …, n, and n is the number of cars in the train. Each car is provided with a front axle and a rear axle, the front axle of the first car is directly controlled to steer by the steering wheel (or the driver), and the front axle of the first car is regarded as the first axle. According to the steering angle of the first axle, the target steering angle of the rear axle of the first car and the target steering angles of the front axles and the rear axles of the other cars are calculated, and then the steering control is performed according to the target steering angles, so as to realize the autonomous steering control of each axle.

[0052] In one specific embodiment of the present application, the steering actuator 5 comprises a reduction gear box 51 and a steering motor 52. The reduction gear box 51 mainly reduces the output of the steering motor 52 to increase the output torque, and at the same time, the worm and gear mechanism in the reduction gear box 51 converts the rotary motion of the steering motor 52 into linear motion, which drives the steering linkage 2 to move through the steering longitudinal rod 6. The steering motor 52 is used to generate a positive rotation or a reverse rotation under the control of the steering control unit 8, and the output shaft of the steering motor 52 is transmitted to the reduction gear box 51, which is the power source of the whole system.

[0053] The steering control unit 8 is the core controller of the electric steering control device and is the key to realize single-axle active steering. The steering control unit 8 receives the steering control command from the steering controller 7 through Ethernet to control the forward rotation or reverse rotation of the steering motor 52.

[0054] The steering controller 7 is the core unit of the multi-axle super virtual track train steering control. The steering controller 7 is used to acquire the steering angle of the first axle, the train running speed and the running direction. The steering controller 7 is used to calculate the target steering angle of the rear axle of the first car and the target steering angles of the front axle and the rear axle of the ith car according to the steering angle of the first axle, the train running speed and the running direction (such as formula (16) and (17)). The steering controller 7 is used to generate the steering control command of each axle according to the target steering angles of the front axle and the rear axle of each car and send the steering control command to the corresponding steering control unit 8 through Ethernet as the command signal of the steering control.

[0055] In one specific embodiment of the present application, mechanical stops 9 and limit switches 10 are arranged on both sides of the vehicle body frame. The limit switches 10 are arranged on the side of the mechanical stops 9 away from the vehicle body frame, so that the mechanical stops 9 serve as the highest level limit, the limit switches 10 (i.e. the hard limit) serve as the secondary limit, and the soft limit serves as the lowest level limit. The mechanical stops 9 not only serve as the highest level limit of the steering movement, but also have the function of single-axle steering parameter calibration.

[0056] In one specific embodiment of the present application, each electric steering control device further comprises a displacement sensor 3. One end of the displacement sensor 3 is connected to the vehicle body frame, and the other end of the displacement sensor 3 is connected to the mechanical stop 9. The displacement sensor 3 is used to detect the lateral displacement (i.e. the displacement caused by relative movement) of the steering linkage mechanism 2 driven by the reduction gear box 51 and transmit the lateral displacement to the steering control unit 8. The steering control unit 8 controls the action of the steering motor 52 according to the lateral displacement to realize accurate control of the lateral displacement.

[0057] Based on the same inventive concept, as shown in Figure 3 The present application also provides an electric steering control method of a super virtual track train, which comprises the following steps:

[0058] 1. Collection of steering angles: The angle sensor collects the steering angles of each axle. The steering angles of each axle are sent to the steering control unit, which then sends the steering angles to the steering controller through Ethernet. The steering angles of each axle include the steering angles of the front axle and the rear axle of each car. The steering angle of the front axle of the first car is the steering angle of the first axle. When the driver controls the steering according to the road conditions, the steering wheel is rotated, thereby driving the first axle to rotate (the steering angle of the steering wheel is the steering angle of the first axle). The other axles are rotated according to the rotation of the first axle.

[0059] 2. Calculation of target steering angles of other axles

[0060] The steering controller receives the steering angles of each axle and calculates the target steering angles of the rear axle of the first car, as well as the target steering angles of the front and rear axles of the i-th car, based on the steering angle of the first axle, the train speed, and the direction of travel. Here, i = 2, 3, ..., n, and n is the number of cars in the train.

[0061] The calculation process of the target steering angle of this invention will be illustrated using a four-axle vehicle as an example:

[0062] Establish a dynamic model of a single-section vehicle, such as Figure 4 The illustrated two-degree-of-freedom vehicle dynamics model allows for independent steering of both the front and rear wheels. A Cartesian coordinate system is established with the center of the first axle as the origin, the train's forward direction as the negative Y-axis, and the right side perpendicular to the forward direction as the positive X-axis (the negative Y-axis rotated 90° clockwise becomes the positive X-axis). When the wheels are parallel to the forward direction, both the lateral displacement and steering angle are defined as 0; leftward deflection is positive, and rightward deflection is negative.

[0063] The lateral dynamics equations for the two-wheel model are:

[0064] ∑F=m(rv x +a y (1)

[0065] Where F is the lateral force acting on the vehicle, m is the total mass of the vehicle, r is the yaw rate of the vehicle's center of gravity, and v x and v y Let a be the components of the vehicle's speed in the x and y directions. y This refers to the vehicle's lateral acceleration. (By...) Figure 4 It can be seen that the resultant force of the external forces acting on the two-degree-of-freedom vehicle along the y-axis is:

[0066] ∑F=F1cosδ f +F2cosδ r (2)

[0067] Among them, F1 and F2 are the lateral reaction forces exerted by the ground on the front and rear wheels, i.e., the lateral deflection forces, δ f δ r These are the steering angles of the front and rear wheels, respectively. Since the steering angle of the wheels is generally very small during vehicle movement to ensure vehicle stability, combining equations (1) and (2) reveals that:

[0068] m(rv x +a y )=F1+F2=C1β1+C2β2 (3)

[0069] Where β1 and β2 are the slip angles of the front and rear wheels of the vehicle, respectively, and C1 and C2 are the slip stiffnesses of the front and rear tires, respectively, with the following values:

[0070]

[0071] Where, ξ f Let l be the angle between the vehicle's front wheel velocity u1 and the positive x-axis. f l r These are the distances from the front and rear axles to the vehicle's center of gravity, respectively, and β is the sideslip angle of the vehicle's center of gravity, β = v y / v x From equation (4), the sideslip angle β1 of the vehicle's front wheels can be obtained as:

[0072]

[0073] Similarly, the rear wheel slip angle can be obtained as follows:

[0074]

[0075] Combining equations (3), (5), and (6), we can obtain the formula for calculating the rear wheel steering angle:

[0076]

[0077] That is, the steering angle of the rear axle of the first vehicle can be calculated by combining the steering angle of the first axle with the vehicle parameters.

[0078] Extended to two-section, four-axle vehicles, such as Figure 5 As shown:

[0079] According to γ1 (the steering angle of the front axle of the current car) and formula (7):

[0080]

[0081] Where γ2 is the steering angle of the rear axle of the current car, points A1 to A4 are the centers of mass of each wheel, point G1 is the articulation point between the front and rear cars, M is the instantaneous center of the turn, and R1 to R4 are the distances from the corresponding wheel centers of mass to the instantaneous center of the turn M. In triangle ΔMG1A2:

[0082]

[0083] Therefore, the distance R from the hinge point G1 to the instantaneous center of the turn M can be obtained by using the law of cosines. g1 for:

[0084]

[0085] The angle of ∠MG1A2 can then be calculated as follows:

[0086] ∠MG1A2=arcsin(R2 sinβ1 / R g1 (11)

[0087] Then in triangle ΔMG1A3, the angle of ∠MG1A3 can be calculated as:

[0088] ∠MG1A3= π - ∠MG1A2- φ1 (12)

[0089] wherein φ1 is the angle value of the hinge point G1, which can be collected by an angle sensor.

[0090] According to formula (12), the value of R3 can be calculated as:

[0091]

[0092] Therefore, the front axle steering angle of the second section vehicle can be calculated as:

[0093]

[0094] According to formula (14) to calculate the front axle steering angle γ3 of the second section vehicle and formula (7), the rear axle steering angle γ4 of the second section vehicle can be calculated as:

[0095]

[0096] Finally, the steering controller sends the steering angles of each axle to the corresponding steering control unit of the axle.

[0097] By analogy, assuming that the number of train sections is n, the calculation formulas of the target steering angles of the front axle and the rear axle of the ith section vehicle are respectively:

[0098]

[0099] wherein γ 2i-1 is the target steering angle of the front axle of the ith section vehicle, γ 2i is the target steering angle of the rear axle of the ith section vehicle, when i = 1, γ1 is the first axle steering angle, and γ2 is the target steering angle of the rear axle of the first section vehicle; R gi is the distance from the hinge point G i between the ith section vehicle and the (i-1)th section vehicle to the instantaneous center of rotation M; A 2i-1 is the front wheel center of mass of the ith section vehicle; R 2i-1 is the distance from the front wheel center of mass A 2i-1 of the ith section vehicle to the instantaneous center of rotation M; is the front wheel cornering stiffness of the ith section vehicle, is the rear wheel cornering stiffness of the ith section vehicle, β is the cornering angle of the vehicle center of mass, is the length of the front axle of the ith section vehicle from the vehicle center of mass, is the length of the rear axle of the ith section vehicle from the vehicle center of mass.

[0100] 3. Generating steering control instructions: the steering controller sends the target steering angle of each axle to the steering control unit, and the steering control unit generates the steering control instructions of each axle according to the target steering angle and the steering angle collected by the angle sensor, or the steering controller receives the steering angle of each axle, generates the steering control instructions of each axle according to the target steering angle and the steering angle collected by the angle sensor, and sends the steering control instructions to the steering control unit. The specific implementation process of generating the steering control instructions is as follows:

[0101] 3.1: Obtaining the real-time steering angle of the axle;

[0102] 3.2: Calculating the steering deviation between the real-time steering angle and the target steering angle of the axle;

[0103] 3.3: Based on the PID control mode, generating the steering control instructions according to the steering deviation, and the PID control equation is:

[0104]

[0105] Wherein, K d is the differential factor of PID control, K p is the proportional factor of PID control, K i is the integral factor of PID control, and δ t is the steering deviation.

[0106] 4. Generating steering action instructions

[0107] The steering control unit generates the steering action instructions according to the steering control instructions, and sends the steering action instructions to the steering actuator.

[0108] 5. Three-level steering limit judgment

[0109] Before sending the steering action instructions to the steering actuator, three-level steering limit judgment is performed to avoid continuing steering when the target steering angle cannot be achieved, thereby improving the steering safety. The three-level steering limit includes steering soft limit, steering hard limit and mechanical stop limit, and the level order is sequentially increased, i.e. the mechanical stop is the maximum limit, and the soft limit is the minimum limit. The limit angle relationship of the three levels is shown in Figure 6 30 (soft limit). 20 (soft limit). 10 (soft limit).

[0110] (1) The specific implementation process of the steering soft limit judgment is as follows:

[0111] The steering control unit judges the relationship between the target steering angle of each axle in the next steering period and the soft limit threshold in the current steering period (or the current sampling period of the angle sensor):​

[0112] If the target steering angle of the axle ≥ γ 10 or the target steering angle of the axle ≤ - γ 10 , the target steering angle exceeds the positive soft limit or the target steering angle exceeds the negative soft limit, no steering action instruction is sent to the steering actuator, a soft limit signal is sent to the steering controller through Ethernet, and then a steering warning is sent to the driver, prompting the driver to pay attention to safety, and the next level of steering limit is judged;

[0113] If - γ 10 < the target steering angle of the axle < γ 10 (i.e. the steering swing arm runs in this interval range), a steering action instruction is sent to the steering actuator to drive the corresponding steering actuator to act; wherein γ 10 is the soft limit threshold. For example, the maximum steering angle is 22°, and the soft limit threshold γ 10 is set to 20°.

[0114] (2) According to the electrical signal of the limit switch installed in front of the mechanical stop, it is judged whether the corresponding axle moves to the hard limit;

[0115] If the steering control unit receives the limit switch electrical signal (the steering swing arm moves to - γ 20 or γ 20 ), it indicates that the current axle steering reaches the hard limit, indicating that the soft limit is invalid or a fault occurs to cause the steering angle to be too large, no steering action instruction is sent to the steering actuator (to prevent continuous steering), and a hard limit signal is sent to the steering controller through Ethernet, and then an alarm is sent to the VCU that the electric power steering device has a fault, and an emergency braking operation is performed; if the limit switch electrical signal is not received (i.e. the steering swing arm runs in the interval range of - γ 20 ~ γ 20 ), the corresponding steering actuator is driven to act or the next level of limit is judged.

[0116] (3) The mechanical stop is the last safeguard for the electric power steering device, if the soft limit and the limit switch are both invalid, the steering swing arm will hit the mechanical stop ( γ 30 or - γ 30 ), to prevent the steering angle from further increasing and prevent the train from turning too large to cause overturning and other dangerous behaviors.

[0117] In one embodiment of the present application, the soft limit, the hard limit and the mechanical stop can be used as the steering limit of the present application, and two or more of them can be used as the steering limit of the present application. When there are two or more steering limits, the lower level steering limit is determined first, and then the higher level steering limit is determined. For example, when the steering limit includes the soft limit and the hard limit, the soft limit is determined first, and then the hard limit is determined. For another example, when the steering limit includes the hard limit and the mechanical stop, the hard limit is determined first, and then the mechanical stop is used as the last limit barrier.

[0118] 6. The steering actuator executes the action: when the limit condition is met (i.e. the steering swing arm is within a reasonable range), the steering action instruction is sent to the steering actuator, the steering actuator executes the action, and the corresponding wheels at both ends of the axle are driven to rotate through the steering longitudinal pull rod and the trapezoidal steering linkage mechanism; the lateral displacement is detected by the displacement sensor and sent to the steering control unit as the feedback input of the steering motor closed-loop control.

[0119] Between steps 4 and 5, a fault detection step is also included to determine whether the electric steering control device has a fault, including communication failure, data error, power supply failure and equipment failure, etc. If there is a fault, the next step is not executed, and the fault information is sent back to the steering control unit through the Ethernet; at the same time, an alarm instruction is sent to the VCU (vehicle controller) to inform the driver that the steering control system has a fault and to perform an emergency braking operation.

[0120] The angle sensor collects the steering angle at each sampling period, and the steering angle of the first axle is used to calculate the target steering angle of the other axles in the next steering period, and the steering controller or steering control unit generates a steering control instruction to realize closed-loop control. Although closed-loop control can make the target steering angle consistent with the collected steering angle, in order to make the steering control more accurate, the collected steering angle is still used in each steering period.

[0121] The entire steering control process is executed as long as the train is powered on, and there is no adjustment to the target steering angle to end the control process, because single axle steering adjustment is a dynamic adjustment process, and the process will only be terminated when the power supply of the steering control system is interrupted.

[0122] Single axle autonomous steering control is a double closed-loop control, the inner loop is a position loop, and the lateral displacement feedback by the displacement sensor is used as the input of the inner loop feedback; the outer loop is an autonomous steering control loop, and the steering action instruction is generated according to the feedback of the angle sensor and the calculated target steering angle, and the steering action instruction is used as another input of the inner loop, and the two inputs of the inner loop are processed and then applied to the steering motor. Among them: the steering state control of the outer loop mainly uses PID control.

[0123] The above merely provides the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of the changes or modifications within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. An electric steering control system for a super virtual track train, characterized by, The electric steering control device comprises a steering controller and an electric steering control device configured for each axle of each car, each electric steering control device comprising: a steering linkage mechanism arranged on the car body chassis and connected with the corresponding axle, for driving the rotation of the wheels on the axle under the drive of a steering actuator; an angle sensor arranged on the car body chassis and the steering linkage mechanism respectively, for collecting the steering angle of the corresponding axle; a steering actuator arranged on the car body chassis and connected with the steering linkage mechanism, for acting according to a steering action instruction; a steering control unit for receiving the steering angle of the corresponding axle and sending the steering angle to the steering controller; receiving a steering control instruction of the corresponding axle and sending a steering action instruction to the steering actuator according to the steering control instruction; the steering controller acquires the steering angle of the first axle, the running speed of the train and the running direction; calculates the target steering angle of the rear axle of the first car and the target steering angles of the front and rear axles of the ith car according to the steering angle of the first axle, the running speed of the train and the running direction; generates the steering control instruction of each axle according to the target steering angles of the front and rear axles of each car; wherein the first axle refers to the front axle of the first car and is directly controlled by the steering wheel, i = 2, 3, …, n, n is the number of cars, and the specific formula of the target steering angle is: where γ 2i-1 is the target steering angle of the front axle of the ith segment, γ 2i is the target steering angle of the rear axle of the ith segment, when i = 1, γ1 is the first axle steering angle, γ2 is the target steering angle of the rear axle of the first segment; R gi is the distance from the hinge point G i between the ith segment and the ith-1 segment to the center of instantaneous turning M; A 2i-1 is the front wheel center of gravity of the ith segment; R 2i-1 is the front wheel center of gravity A 2i-1 of the ith segment to the center of instantaneous turning M; is the front wheel cornering stiffness of the ith segment, is the rear wheel cornering stiffness of the ith segment, β is the cornering angle of the vehicle center of gravity, v x is the component of train running speed in the x direction, r is the yaw rate of the vehicle center of gravity, is the length of the front axle of the ith segment from the vehicle center of gravity, is the length of the rear axle of the ith segment from the vehicle center of gravity, m is the total vehicle mass, a y is the lateral acceleration of the vehicle.

2. The electric steering control system of the super virtual track train according to claim 1, wherein, the steering linkage mechanism is a trapezoidal steering linkage mechanism, which comprises a first steering rocker, a first connecting rod, an I-shaped arm, a cross rod, an L-shaped arm, a second connecting rod and a second steering rocker connected in sequence; the I-shaped arm and the L-shaped arm are arranged on the car body chassis; the first steering rocker and the second steering rocker are connected with both ends of the corresponding axle respectively; the L-shaped arm is connected with the steering actuator.

3. The electric steering control system of the super virtual track train according to claim 2, wherein, The steering linkage mechanism is connected with the steering actuator through a steering longitudinal rod.

4. The electric steering control system of the super virtual track train according to claim 2, wherein, The steering actuator comprises a reduction gear box and a steering motor.

5. The electric steering control system of the super virtual track train according to claim 2, wherein, Mechanical stops and limit switches are arranged on both sides of the car body chassis, and the limit switches are located on the side away from the car body chassis of the mechanical stops.

6. The electric steering control system of the super virtual track train according to any one of claims 1 to 5, characterized in that, Each electric steering control device further comprises a displacement sensor for detecting the lateral displacement of the steering linkage mechanism and transmitting the lateral displacement to the steering control unit; The steering control unit controls the action of the steering actuator according to the lateral displacement, realizing accurate control of the lateral displacement.

7. A super virtual orbit train electric steering control method, characterized by, The method comprises the following steps: acquiring the steering angle of the first axle, the running speed of the train and the running direction, wherein the first axle refers to the front axle of the first car and is directly controlled by the steering wheel; calculating the target steering angle of the rear axle of the first car and the target steering angles of the front and rear axles of the ith car according to the steering angle of the first axle, the running speed of the train and the running direction, wherein i = 2, 3, …, n, n is the number of cars, and the specific formula is: wherein γ 2i-1 is the target steering angle of the front axle of the ith section, γ 2i is the target steering angle of the rear axle of the ith section, when i = 1, γ1 is the first axle steering angle, γ2 is the target steering angle of the rear axle of the first section; R gi is the distance from the hinge point G i between the ith section and the ith-1 section to the center of instantaneous turning M; A 2i-1 is the front wheel center of gravity of the ith section; R 2i-1 is the front wheel center of gravity A 2i-1 of the ith section to the center of instantaneous turning M; is the front wheel cornering stiffness of the ith section, is the rear wheel cornering stiffness of the ith section, β is the cornering angle of the vehicle center of gravity, v x is the component of the train running speed in the x direction, r is the yaw rate of the vehicle center of gravity, is the length of the front axle of the ith section from the vehicle center of gravity, is the length of the rear axle of the ith section from the vehicle center of gravity, m is the total vehicle mass, a y is the vehicle lateral acceleration; generating the steering control instruction of each axle according to the target steering angles of the front and rear axles of each car, driving the corresponding steering actuator to act according to the steering control instruction, and realizing electric active steering control of each car.

8. The super virtual orbit train electric steering control method according to claim 7, characterized in that: Before driving the corresponding steering actuator according to the steering control instruction, the control method further comprises a step of judging whether the steering limit is reached according to the target steering angle of the axle, and the specific implementation process is as follows: If the target steering angle of the axle ≥ γ 10 or the target steering angle of the axle ≤ - γ 10 a steering warning is issued to the driver, and it is determined whether a limit switch signal is received; if the limit switch signal is received, an alarm is issued, and an emergency braking operation is performed; if the limit switch signal is not received, the corresponding steering actuator is driven to act. If - γ 10 < Target steering angle of the vehicle < γ 10 , drive the corresponding steering actuator; wherein, γ 10 is a soft limit threshold.

9. The super virtual orbit train electric steering control method according to claim 7 or 8, characterized by: The specific implementation process of generating the steering control instruction of each axle according to the target steering angle of each front axle and rear axle is as follows: Obtaining the real-time steering angle of the axle; Calculating the steering deviation between the real-time steering angle and the target steering angle of the axle; Generating the steering control instruction according to the steering deviation based on the PID control mode.

10. A super virtual track train, characterized by: The electric power steering control system according to any one of claims 1-6.

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