Super virtual rail train and electric steering control system and control method thereof

Abstract

The invention discloses a super virtual rail train and an electric steering control system and control method thereof. The control method comprises the steps that the steering angle of a first axle, the train running speed and the running direction are obtained; calculating a target steering angle of a rear axle of the first section of train and target steering angles of a front axle and a rear axle of the i-th section of train according to the steering angle of the first axle, the running speed of the train and the running direction of the train; and generating a steering control instruction of each axle according to the target steering angles of the front axle and the rear axle of each section of vehicle, and driving a corresponding steering actuator to act according to the steering control instruction to realize electric active steering control of each section of vehicle. According to the method, autonomous steering control over the corresponding axles is achieved according to the target steering angle, each section of vehicle can run along a fixed path, the driving burden of a driver is relieved, meanwhile, the vehicle can achieve accurate virtual track following control, and the response speed higher than that of hydraulic steering is obtained.

Description

Technical Field

[0001] The present invention belongs to the field of rail transportation, and in particular relates to a super virtual rail train and an electric wire-controlled active steering control system and a control method thereof. Background Art

[0002] With the increase in population, the serious aging of the population and the serious traffic congestion, more and more people choose large-scale public transportation with large passenger capacity and no need to drive themselves. Therefore, large-scale public transportation is becoming more and more a choice for people to travel. The multi-axle heavy-load super virtual rail train composed of multiple sections has the characteristics of large capacity, low cost, intelligence and 100% low floor, and is gradually becoming the mainstream development product of green and intelligent transportation in the future.

[0003] The multi-axle, heavy-loaded super virtual rail train is formed by multiple articulated cars. The interior of the vehicle is designed according to rail transit standards. It has the characteristics of a long body, multiple axles and heavy axles. When the driver drives the super virtual rail train around a corner, there are difficulties such as large road width, poor flexibility, untimely steering and large errors. The train is prone to skidding and deviating from the lane, which may cause traffic accidents.

[0004] At present, trains use hydraulic steering systems to achieve active steering of a single axle. However, the pipelines and equipment of the hydraulic actuators are complex, and there is a risk of oil leakage in the hydraulic pipelines, which brings difficulties to both use and maintenance. Summary of the invention

[0005] The purpose of the present invention is to provide a super virtual rail train and its electric steering control system and control method, so as to solve the problems that the traditional hydraulic steering system pipelines and equipment are complicated and not easy to arrange under the vehicle, there is a risk of oil leakage in the hydraulic pipelines, increased pollution to the environment, and the steering control is not timely and has large errors.

[0006] The present invention solves the above technical problems through the following technical solutions: an electric steering control system for a super virtual rail train, comprising a steering controller and an electric steering control device configured for each axle of each car, each electric steering control device comprising:

[0007] A steering linkage mechanism is provided on the vehicle body chassis and connected to 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, with two ends disposed on the vehicle body chassis and the steering linkage, for collecting the steering angle of the corresponding axle;

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

[0010] A steering control unit, configured to receive a steering angle of a corresponding axle and send the steering angle to a steering controller; receive a steering control instruction of a corresponding axle and send a steering action instruction to the steering actuator according to the steering control instruction;

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

[0012]

[0013] Among them, γ 2i-1 is the target steering angle of the front axle of the i-th vehicle, γ 2i is the target steering angle of the rear axle of the i-th vehicle. 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 vehicle. gi is the hinge point G between the i-th car and the i-1-th car i The distance to the instantaneous center of the turn M; A 2i-1 is the center of mass of the front wheel of the i-th vehicle; R 2i-1 A is the center of mass of the front wheel of the i-th vehicle 2i-1 The distance to the instantaneous center M of the turn; is the front wheel cornering stiffness of the i-th vehicle, is the rear wheel cornering stiffness of the i-th vehicle, β is the side slip angle of the vehicle center of mass, v x is the component of the train speed in the x direction, r is the yaw angular velocity of the vehicle center of mass, is the distance from the front axle of the i-th vehicle to the center of mass of the vehicle, is the distance between the rear axle of the i-th vehicle and the center of mass of the vehicle, m is the mass of the vehicle, a y is the lateral acceleration of the vehicle.

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

[0015] Furthermore, the steering linkage mechanism is connected to the steering actuator via a steering longitudinal tie rod.

[0016] Furthermore, the steering actuator includes a reduction gear box and a steering motor.

[0017] Furthermore, mechanical stops and limit switches are provided on both sides of the vehicle body underframe, and the limit switch is located on the side of the mechanical stop away from the vehicle body underframe.

[0018] Furthermore, each of the electric steering control devices further comprises a displacement sensor, which is used to detect the lateral displacement of the steering linkage mechanism and transmit the lateral displacement to the steering control unit;

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

[0020] Based on the same inventive concept, the present invention also provides a super virtual track train electric steering control method, comprising the following steps:

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

[0022] The target steering angle of the rear axle of the first train section and the target steering angles of the front axle and the rear axle of the i-th train section are calculated according to the steering angle of the first axle, the train running speed and the driving direction, where i=2,3,…,n, and n is the number of train sections. The specific formula is:

[0023]

[0024] Among them, γ 2i-1 is the target steering angle of the front axle of the i-th vehicle, γ 2i is the target steering angle of the rear axle of the i-th vehicle. 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 vehicle. gi is the hinge point G between the i-th car and the i-1-th car i The distance to the instantaneous center of the turn M; A 2i-1 is the center of mass of the front wheel of the i-th vehicle; R 2i-1 A is the center of mass of the front wheel of the i-th vehicle 2i-1 The distance to the instantaneous center M of the turn; is the front wheel cornering stiffness of the i-th vehicle, is the rear wheel cornering stiffness of the i-th vehicle, β is the side slip angle of the vehicle center of mass, v x is the component of the train speed in the x direction, r is the yaw angular velocity of the vehicle center of mass, is the distance from the front axle of the i-th vehicle to the center of mass of the vehicle, is the distance between the rear axle of the i-th vehicle and 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 for each axle are generated according to the target steering angles of the front axle and the rear axle of each vehicle section, and the corresponding steering actuator is driven according to the steering control instructions to realize the electric active steering control of each vehicle section.

[0026] Furthermore, before driving the corresponding steering actuator to act according to the steering control instruction, the control method further includes 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:

[0027] 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 a limit switch electrical signal is received, an alarm is issued and an emergency braking operation is performed; if no limit switch electrical signal is received, the corresponding steering actuator is driven to act;

[0028] If -γ 10 <Target steering angle of axle<γ 10 , then the corresponding steering actuator is driven; where γ 10 is the soft limit threshold.

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

[0030] Get the real-time steering angle of the axle;

[0031] Calculate the steering deviation between the real-time steering angle of the axle and the target steering angle;

[0032] Based on the PID control method, a steering control instruction is generated according to the steering deviation.

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

[0034] Beneficial Effects

[0035] Compared with the prior art, the advantages of the present invention are:

[0036] The present invention provides a super virtual track train and its electric steering control system and control method, each axle is equipped 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 implemented according to the target steering angle, so that each car can travel along a fixed path, reducing the driving burden of the driver, and at the same time enabling the vehicle to achieve precise virtual track following control and obtain a faster response speed than hydraulic steering.

[0037] Compared with the traditional hydraulic steering system, it reduces complex pipelines and equipment, making the entire steering control system simple and clear, and easy to arrange under the vehicle; the electric steering control system completely decouples the steering wheel action from the steering of each axle, making the control of each axle more precise; shortens the system's response time and improves the accuracy of steering control; there is no risk of oil leakage in the hydraulic pipeline, which reduces environmental pollution and is in line with the development concept of green and intelligent transportation. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only one embodiment of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0039] Figure 1 is a schematic structural diagram of an electric steering control system in an embodiment of the present invention;

[0040] Figure 2 is a schematic structural diagram of a steering linkage mechanism in an embodiment of the present invention;

[0041] Figure 3 This is a flow chart of the electric steering control method for a super virtual rail train in an embodiment of the present invention;

[0042] Figure 4 is a dynamic model of a single-section vehicle in an embodiment of the present invention;

[0043] Figure 5 It is a train model with two cars and four axles in an embodiment of the present invention;

[0044] Figure 6 Schematic diagram of three-level positive and negative limit in an embodiment of the present invention.

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

[0046] The following is a clear and complete description of the technical solutions in the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

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

[0048] The super virtual rail train is composed of multiple cars, each axle of each car is equipped with an electric steering control device, and the whole train shares a steering controller 7 (i.e., STCU). Figure 1 As shown, 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 to 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 to the vehicle chassis, with wheels installed at both ends to bear the weight of the vehicle body; the axle serves as the final actuator of the steering control, driving the left and right deflection of the wheels at both ends through the steering linkage mechanism 2. In a specific embodiment of the present invention, Figure 1 and 2As shown, the steering linkage mechanism 2 is a trapezoidal steering linkage mechanism 2, which includes a first steering rocker arm 21, a first connecting rod 22, an I-shaped arm 23, a tie rod 24, an L-shaped arm 25, a second connecting rod 26 and a second steering rocker arm 27 connected in sequence; the I-shaped arm 23 and the L-shaped arm 25 are arranged on the vehicle body chassis; the first steering rocker arm 21 and the second steering rocker arm 27 are respectively connected to the two ends of the axle; the L-shaped arm 25 is connected to the steering actuator 5 through the steering longitudinal tie rod 6. The L-shaped arm 25 is connected to the steering longitudinal tie rod 6 through a ball joint to eliminate vibration. When the steering actuator 5 generates steering power, the first steering rocker arm 21 and the second steering rocker arm 27 are driven to move through the tie rod 24, the I-shaped arm 23 and the L-shaped arm 25, and the steering power is transmitted to the two ends of the axle, acting on the wheels to achieve left and right deflection of the wheels. The steering longitudinal tie rod 6 is used to transmit the steering power and displacement output by the steering actuator 5 to the steering linkage mechanism 2 to drive the wheels to rotate.

[0050] There are two angle sensors 4, one end of which 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 this embodiment, each car is numbered, the first car is the car where the driver's cab is located, and the other cars are the second car, the third car, ..., the i-th car, ..., 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, and the front axle of the first car is directly controlled by the steering wheel (or the driver). The front axle of the first car is set as the first axle. The present invention calculates the target steering angle of the rear axle of the first car and the target steering angles of the front axles and rear axles of other cars according to the steering angle of the first axle, and then performs steering control according to the target steering angle to achieve autonomous steering control of each axle.

[0052] In a specific embodiment of the present invention, the steering actuator 5 includes a reduction gearbox 51 and a steering motor 52. The reduction gearbox 51 mainly increases the output torque by reducing the output of the steering motor 52. At the same time, the worm gear mechanism in the reduction gearbox 51 converts the rotational motion of the steering motor 52 into linear motion, and drives the steering linkage 2 to move through the steering longitudinal tie rod 6. The steering motor 52 is used to generate forward or reverse motion under the control of the steering control unit 8, and is transmitted to the reduction gearbox 51 through the output shaft of the steering motor 52, and is the power source of the entire system.

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

[0054] The steering controller 7 is the core unit of the steering control of the multi-axle super virtual track train, which is used to obtain the steering angle of the first axle, the train running speed and the driving direction; according to the steering angle of the first axle, the train running speed and the driving direction, the target steering angle of the rear axle of the first vehicle section and the target steering angles of the front axle and the rear axle of the i-th vehicle section are calculated (such as formulas (16) and (17)); according to the target steering angles of the front axle and the rear axle of each vehicle section, the steering control instructions of each axle are generated, and sent to the corresponding steering control unit 8 via Ethernet as a steering control command signal.

[0055] In a specific embodiment of the present invention, mechanical stops 9 and limit switches 10 are provided on both sides of the vehicle chassis, and the limit switch 10 is located on the side of the mechanical stop 9 away from the vehicle chassis, so that the mechanical stop 9 is used as the highest level limit, the limit switch 10 (i.e., the hard limit) is used as the secondary limit, and the soft limit is used as the lowest level limit. In addition to being the highest level limit of the steering movement, the mechanical stop 9 also has the function of calibrating the single-axis steering parameters.

[0056] In a specific embodiment of the present invention, each electric steering control device also includes a displacement sensor 3, one end of which is connected to the vehicle body frame, and the other end is connected to the mechanical stopper 9, for detecting 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 transmitting 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 achieve precise control of the lateral displacement.

[0057] Based on the same inventive concept, Figure 3 As shown, an embodiment of the present invention also provides a super virtual track train electric steering control method, comprising the following steps:

[0058] 1. Collection of steering angle: Angle sensors collect the steering angles of each axle, which are sent to the steering control unit, which then sends them to the steering controller via Ethernet. The steering angles of each axle include the steering angles of the front axle and the rear axle of each section of the vehicle. The steering angle of the front axle of the first section of the vehicle is the steering angle of the first axle. When the driver controls the steering according to the road conditions, the steering wheel is controlled to rotate, which in turn drives the first axle to rotate (the steering angle of the steering wheel is the steering angle of the first axle), and the other axles rotate according to the rotation of the first axle.

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

[0060] The steering controller receives the steering angles of each axle and 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 i-th car according to the steering angle of the first axle, the train speed and the travel direction, where i = 2, 3, ..., n, where n is the number of train cars.

[0061] The calculation process of the target steering angle of the present invention is described by taking a four-axle vehicle as an example:

[0062] Establish a dynamic model of a single-section vehicle, such as Figure 4 The two-degree-of-freedom vehicle dynamics model shown in the figure can steer the front and rear wheels independently. A rectangular coordinate system is established with the center of the first axle as the origin, the train's forward direction as the negative direction of the Y axis, and the right side perpendicular to the train's forward direction as the positive direction of the X axis (the negative direction of the Y axis rotates 90° clockwise to the positive direction of the X axis). When the wheels are parallel to the forward direction, the lateral displacement and steering angle are defined as 0, the left deflection is positive, and the right deflection is negative.

[0063] The lateral dynamics equation of the two-wheel model is:

[0064] ∑F=m(rv x +a y ) (1)

[0065] Where F is the lateral force on the vehicle, m is the mass of the vehicle, r is the yaw rate of the vehicle's center of mass, and v x and v y is the component of the vehicle's running speed in the x and y directions, a y is the lateral acceleration of the vehicle. Figure 4 It can be seen that the resultant force of the external force on the two-degree-of-freedom vehicle along the y-axis direction is:

[0066] ∑F=F1cosδ f +F2cosδ r (2)

[0067] Among them, F1 and F2 are the lateral reaction forces of the ground on the front and rear wheels, that is, the cornering force, δ f , δ r are the steering angles of the front and rear wheels respectively. During the vehicle movement, in order to ensure the stability of the vehicle, the steering angle of the wheel is generally very small. Therefore, combining equations (1) and (2), we can know that:

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

[0069] Among them, β1 and β2 are the side slip angles of the front and rear wheels of the vehicle, respectively, and C1 and C2 are the side slip stiffness of the front and rear tires, respectively, and their values ​​are:

[0070]

[0071] Among them, ξ f is the angle between the front wheel speed u1 and the positive direction of the x-axis, l f , l r are the lengths of the front and rear axles from the vehicle’s center of mass, β is the side slip angle of the vehicle’s center of mass, β = v y / v x From formula (4), the side slip angle β1 of the front wheel of the vehicle can be obtained as:

[0072]

[0073] Similarly, the rear wheel slip angle is:

[0074]

[0075] Combining equations (3), (5) and (6), the formula for calculating the rear wheel turning angle is:

[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-carriage four-axle vehicles, such as Figure 5 As shown:

[0079] According to γ1 (the steering angle of the front axle of the current vehicle) and formula (7), we can know that:

[0080]

[0081] Among them, γ2 is the steering angle of the rear axle of the current car, points A1~A4 are the center of mass of each wheel, point G1 is the hinge point of the front and rear cars, M is the instantaneous center of the turn, R1~R4 are the distances from the center of mass of the corresponding wheel to the instantaneous center of the turn M, in the triangle ΔMG1A2:

[0082]

[0083] Therefore, the distance R from the hinge point G1 to the instantaneous center of the turn M can be calculated by the cosine theorem: g1 for:

[0084]

[0085] Then the angle of ∠MG1A2 can be calculated as:

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

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

[0088] ∠MG1A3=π-∠MG1A2-φ1 (12)

[0089] Among them, 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 steering angle of the front axle of the second vehicle can be calculated as:

[0093]

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

[0095]

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

[0097] Similarly, assuming that the number of train sections is n, the calculation formulas for the target steering angles of the front axle and rear axle of the i-th section are:

[0098]

[0099] Among them, γ 2i-1 is the target steering angle of the front axle of the i-th vehicle, γ 2i is the target steering angle of the rear axle of the i-th vehicle. 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 vehicle. gi is the hinge point G between the i-th car and the i-1-th car i The distance to the instantaneous center of the turn M; A 2i-1 is the center of mass of the front wheel of the i-th vehicle; R 2i-1 A is the center of mass of the front wheel of the i-th vehicle 2i-1 The distance to the instantaneous center M of the turn; is the front wheel cornering stiffness of the i-th vehicle, is the rear wheel cornering stiffness of the i-th vehicle, β is the side slip angle of the vehicle’s center of mass, is the distance from the front axle of the i-th vehicle to the center of mass of the vehicle, is the length from the rear axle of the i-th vehicle to the center of mass of the vehicle.

[0100] 3. Generate 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, and the steering controller 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 them to the steering control unit. The specific implementation process of generating the steering control instructions is as follows:

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

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

[0103] 3.3: Based on the PID control method, the steering control command is generated according to the steering deviation. The PID control equation is:

[0104]

[0105] Among them, 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, δ t For steering deviation.

[0106] 4. Generate steering action instructions

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

[0108] 5. Three-level steering limit judgment

[0109] Before issuing a steering action command to the steering actuator, a three-level steering limit judgment must be performed first to avoid continuing to execute steering when the target steering angle cannot be achieved, thereby improving steering safety. The three-level steering limit includes steering soft limit, steering hard limit and mechanical stop limit. The order of levels increases in sequence, that is, the mechanical stop is the maximum limit and the soft limit is the minimum limit. The relationship between the limit angles of these three levels is as follows: Figure 6 As shown, the relationship between the limiting angles of the three levels of limiting is γ 30 (Mechanical stop)>γ 20 (Hard limit)>γ 10 (Soft limit).

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

[0111] The steering control unit determines the relationship between the target steering angle of each axle in the next steering cycle and the soft limit threshold in the current steering cycle (or the current sampling cycle 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, and the steering action command cannot be issued to the steering actuator. The soft limit signal is sent to the steering controller through Ethernet, and then a steering warning is issued to the driver to remind the driver to pay attention to safety and make a judgment on the next level of steering limit;

[0113] If -γ 10 <Target steering angle of axle<γ 10 (i.e. the steering arm operates within this range), a steering action command is sent to the steering actuator to drive the corresponding steering actuator to act; where γ 10 is the soft limit threshold. For example, the maximum steerable angle is 22°, and the soft limit threshold γ 10 Set to 20°.

[0114] (2) judging whether the corresponding axle has moved to the hard limit according to the electrical signal of the limit switch installed in front of the mechanical stop;

[0115] If the steering control unit receives the limit switch electrical signal (steering arm moves to -γ 20 or γ 20 ), it indicates that the current axle steering has reached the hard limit, indicating that the soft limit has failed or a fault has occurred, resulting in a steering angle that is too large, and the steering action command cannot be issued to the steering actuator (preventing further steering), and a hard limit signal is sent to the steering controller via Ethernet, which then sends an alarm to the VCU to notify that the electric steering control device has a fault and performs an emergency braking operation; if the limit switch electrical signal is not received (that is, the steering arm is running at -γ 20 ~γ 20 range), the corresponding steering actuator is driven to act or the next level limit judgment is performed.

[0116] (3) The mechanical stop is the last safeguard for the electric steering control device. If the soft limit and limit switch fail, the steering arm will hit the mechanical stop (γ 30 or -γ 30 ) to prevent the steering angle from increasing further and to prevent the train from turning too much and causing dangerous behaviors such as overturning.

[0117] In a specific embodiment of the present invention, one of the soft limit, the hardware limit and the mechanical stop can be selected as the steering limit of the present invention, or two of them can be selected as the steering limit of the present invention. When there are two or more steering limits, the lower-level steering limit is judged first, and then the higher-level steering limit is judged. Exemplarily, if the steering limit includes a soft limit and a hard limit, the soft limit is judged first, and then the hard limit is judged; for example, if the steering limit includes a hard limit and a mechanical stop, the hard limit is judged first, and then the mechanical stop is used as the final limit barrier.

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

[0119] A fault detection step is also included between steps 4 and 5 to determine whether there is a fault in the electric steering control device. Faults include communication failure, data error, power supply failure, and equipment failure. If a fault exists, the next step is not executed, and the fault information is sent back to the steering control unit via Ethernet; at the same time, an alarm command is sent to the VCU (vehicle control unit) to notify 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 in each sampling cycle. The steering angle of the first axle is used to calculate the target steering angle of the other axles in the next steering cycle, and the steering controller or steering control unit generates a steering control command to achieve closed-loop steering 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, each steering cycle still uses the collected steering angle.

[0121] The entire steering control process is executed as long as the train is powered on. There is no such thing as ending the control process when the target steering angle is adjusted, because single-axis steering adjustment is a dynamic adjustment process, and the process will only terminate when the power supply of the steering control system is interrupted.

[0122] Single-axis autonomous steering control is a double closed-loop control. The inner loop is the position loop, and the lateral displacement fed back by the displacement sensor is used as the input of the inner loop feedback; the outer loop is the autonomous steering control loop, which generates a steering action command based on the steering angle fed back by the angle sensor and the calculated target steering angle. The steering action command is used as another input of the inner loop. The two inputs of the inner loop are processed and act on the steering motor. Among them: the steering state control of the outer loop mainly uses PID control.

[0123] What is disclosed above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of changes or modifications within the technical scope disclosed in the present invention, which should be covered within the protection scope of the present invention.

Claims

1. An electric steering control system for a super virtual track train, characterized in that: It includes a steering controller and an electric steering control device configured for each axle of each vehicle, and each electric steering control device includes: A steering linkage mechanism is provided on the vehicle body chassis and connected to the corresponding axle, and is used to drive the rotation of the wheels on the axle under the drive of the steering actuator; An angle sensor, with two ends disposed on the vehicle body chassis and the steering linkage, for collecting the steering angle of the corresponding axle; A steering actuator, which is arranged on the vehicle body chassis and connected to the steering linkage mechanism, and is used to act according to the steering action instruction; A steering control unit, configured to receive a steering angle of a corresponding axle and send the steering angle to a steering controller; receive a steering control instruction of a corresponding axle and send a steering action instruction to the steering actuator according to the steering control instruction; The steering controller obtains the steering angle of the first axle, the running speed of the train and the driving direction; calculates the target steering angle of the rear axle of the first car section and the target steering angles of the front axle and the rear axle of the i-th car section according to the steering angle of the first axle, the running speed of the train and the driving direction; generates the steering control instructions of each axle according to the target steering angles of the front axle and the rear axle of each car section; wherein, the first axle refers to the front axle of the first car section and its steering is directly controlled by the steering wheel, i=2,3,…,n, n is the number of train sections, and the specific formula of the target steering angle is: Among them, γ 2i-1 is the target steering angle of the front axle of the i-th vehicle, γ 2i is the target steering angle of the rear axle of the i-th vehicle. 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 vehicle. gi is the hinge point G between the i-th car and the i-1-th car i The distance to the instantaneous center of the turn M; A 2i-1 is the center of mass of the front wheel of the i-th vehicle; R 2i-1 A is the center of mass of the front wheel of the i-th vehicle 2i-1 The distance to the instantaneous center M of the turn; is the front wheel cornering stiffness of the i-th vehicle, is the rear wheel cornering stiffness of the i-th vehicle, β is the side slip angle of the vehicle center of mass, v x is the component of the train speed in the x direction, r is the yaw angular velocity of the vehicle center of mass, is the distance from the front axle of the i-th vehicle to the center of mass of the vehicle, is the distance between the rear axle of the i-th vehicle and the center of mass of the vehicle, m is the mass of the vehicle, 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, characterized in that: The steering linkage mechanism is a trapezoidal steering linkage mechanism, which includes a first steering rocker arm, a first connecting rod, an I-shaped arm, a tie rod, an L-shaped arm, a second connecting rod and a second steering rocker arm connected in sequence; the I-shaped arm and the L-shaped arm are arranged on the vehicle body frame; the first steering rocker arm and the second steering rocker arm are respectively connected to the two ends of the corresponding axle; the L-shaped arm is connected to the steering actuator.

3. The electric steering control system of the super virtual track train according to claim 2, characterized in that: The steering linkage is connected to the steering actuator via a steering trailing rod.

4. The electric steering control system of the super virtual track train according to claim 2, characterized in that: The steering actuator includes a reduction gear box and a steering motor.

5. The electric steering control system of the super virtual track train according to claim 2, characterized in that: Mechanical stops and limit switches are provided on both sides of the vehicle body underframe, and the limit switch is located on the side of the mechanical stop away from the vehicle body underframe.

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 of the electric steering control devices further comprises a displacement sensor, the displacement sensor being used to detect the lateral displacement of the steering linkage and transmit the lateral displacement to the steering control unit; The steering control unit controls the action of the steering actuator according to the lateral displacement to achieve precise control of the lateral displacement.

7. A super virtual track train electric steering control method, characterized in that: The following steps are involved: Obtaining the steering angle, train running speed and travel direction of the first axle, wherein the first axle refers to the front axle of the first car and its steering is directly controlled by the steering wheel; The target steering angle of the rear axle of the first train section and the target steering angles of the front axle and the rear axle of the i-th train section are calculated according to the steering angle of the first axle, the train running speed and the driving direction, where i=2,3,…,n, and n is the number of train sections. The specific formula is: Among them, γ 2i-1 is the target steering angle of the front axle of the i-th vehicle, γ 2i is the target steering angle of the rear axle of the i-th vehicle. 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 vehicle. gi is the hinge point G between the i-th car and the i-1-th car i The distance to the instantaneous center of the turn M; A 2i-1 is the center of mass of the front wheel of the i-th vehicle; R 2i-1 A is the center of mass of the front wheel of the i-th vehicle 2i-1 The distance to the instantaneous center M of the turn; is the front wheel cornering stiffness of the i-th vehicle, is the rear wheel cornering stiffness of the i-th vehicle, β is the side slip angle of the vehicle center of mass, v x is the component of the train speed in the x direction, r is the yaw angular velocity of the vehicle center of mass, is the distance from the front axle of the i-th vehicle to the center of mass of the vehicle, is the distance between the rear axle of the i-th vehicle and the center of mass of the vehicle, m is the mass of the vehicle, a y is the vehicle lateral acceleration; The steering control instructions for each axle are generated according to the target steering angles of the front axle and the rear axle of each vehicle section, and the corresponding steering actuator is driven according to the steering control instructions to realize the electric active steering control of each vehicle section.

8. The super virtual track train electric steering control method according to claim 7, characterized in that: Before driving the corresponding steering actuator to act according to the steering control instruction, the control method further includes 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 a limit switch electrical signal is received, an alarm is issued and an emergency braking operation is performed; if no limit switch electrical signal is received, the corresponding steering actuator is driven to act; If -γ 10 <Target steering angle of axle<γ 10 , then the corresponding steering actuator is driven; where γ 10 is the soft limit threshold.

9. The electric steering control method for a super virtual track train according to claim 7 or 8, characterized in that: The specific implementation process of generating the steering control instructions of each axle according to the target steering angles of the front axle and the rear axle of each vehicle section is as follows: Get the real-time steering angle of the axle; Calculate the steering deviation between the real-time steering angle of the axle and the target steering angle; Based on the PID control method, a steering control instruction is generated according to the steering deviation.

10. A super virtual track train, characterized in that: An electric power steering system comprising the electric power steering system according to any one of claims 1 to 6.

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