Steering stability control method and steering stability control system for electric hot metal car

Abstract

The invention provides a steering stability control method and a steering stability control system for an electric molten iron vehicle. The steering stability control method comprises the following steps: acquiring the slip rate of the vehicle and the yaw velocity of the vehicle; performing attitude stability adjustment judgment based on the slip rate and the yaw velocity; if the attitude is required to be stably adjusted, redistributing the torque of each wheel of the vehicle so as to reduce the slip rate; meanwhile, steering of rear wheels is independently controlled according to the yaw velocity so as to assist steering of front wheels of the vehicle. According to the method, the vehicle driving slip rate can be reduced, the vehicle balance swing angle speed is reduced, and the vehicle safety and the vehicle body stability are improved.

Description

Technical Field

[0001] The invention relates to the field of vehicle steering control, and in particular to a steering stability control method and a steering stability control system for an electric molten iron vehicle. Background Art

[0002] Electric hot metal car is a non-road special vehicle used for steel mill transportation. The vehicle adopts a low center of mass and long body design. Although it improves the stability of the vehicle, it also causes the vehicle to increase the steering angle and yaw rate. When the vehicle turns on a road with an angle or potholes, it is easy to slip, causing the vehicle to slide sideways. Summary of the invention

[0003] In view of the above-mentioned shortcomings of the related art, an object of the present invention is to provide a steering stability control method and a steering stability control system for an electric molten iron car, which are used to improve the stability of the vehicle body posture when the vehicle is turning.

[0004] To achieve the above-mentioned purpose and other related purposes, the present invention provides a steering stability control method for an electric molten iron car, the steps of the method comprising: obtaining the slip rate and yaw angular velocity of the vehicle; making a posture stability adjustment judgment based on the slip rate and yaw angular velocity; if posture stability adjustment is required, reallocating the torque of each wheel of the vehicle to reduce the slip rate; and at the same time, independently controlling the steering of the rear wheels according to the yaw angular velocity to assist the steering of the front wheels of the vehicle.

[0005] Optionally, the step of calculating the slip rate of the vehicle includes: monitoring the rotation speed of the driven wheels and the rotation speed of the driving wheels of the vehicle to obtain the actual speed and theoretical speed of the vehicle, and obtaining the slip rate based on the actual speed and the theoretical speed.

[0006] Optionally, the method of acquiring the yaw angular velocity includes formula calculation or sensor monitoring.

[0007] Optionally, before redistributing the torque of each wheel of the vehicle, the contact pressure of each wheel needs to be calculated first, and then the wheel torque ratio on the coaxial line is calculated based on the contact pressure of each wheel, and then the torque of the wheels on the coaxial line is redistributed based on the wheel torque ratio.

[0008] Optionally, the mass of the vehicle body, the load mass, and the body inclination angle when the vehicle turns need to be collected when calculating the contact pressure of each wheel.

[0009] Optionally, the specific steps of calculating the wheel torque ratio on the same axis based on the contact pressure of each wheel are: based on the recalculated contact pressure of each wheel, calculating the ratio of the contact pressure of the inner wheel and the outer wheel on the same axis.

[0010] Optionally, the forms of rear wheel steering include reverse steering, vertical steering and same-direction steering. The reverse steering means that the steering of the rear wheels is opposite to the steering of the front wheels, the vertical steering means that the steering angle of the rear wheels is zero, and the same-direction steering means that the steering of the rear wheels is the same as the steering of the front wheels.

[0011] Optionally, the reverse steering, vertical steering and same-direction steering of the rear wheels correspond to situations where the yaw angular velocity is from large to small, respectively.

[0012] A steering stability control system includes: a wheel speed monitoring unit for monitoring the wheel speed of each wheel; a body inclination monitoring unit for monitoring changes in the body inclination of the vehicle during steering; a rear wheel steering unit for independently adjusting the steering of the rear wheels; a wheel drive unit for driving the driving wheels of the vehicle; a wheel brake unit for braking the driven wheels of the vehicle; a control unit for calculating the slip rate and yaw rate of the vehicle based on information collected by the wheel speed monitoring unit and the body inclination monitoring unit, and performing posture stability adjustment judgment, the control unit is also used to control the wheel drive unit and the wheel brake unit to redistribute the driving torque to the driving wheels and the torque to the driven wheels, and control the rear wheel steering unit to steer the rear wheels to assist the steering of the front wheels of the vehicle.

[0013] As described above, the electric molten iron car steering stability control method and steering stability control system of the present invention have the following beneficial effects: the method can reduce the vehicle driving slip rate and improve the energy utilization efficiency; by dynamically controlling the vehicle driving torque and braking torque, the vehicle body stability is improved; since the rear vehicle road is an independent steering mechanism, the vehicle yaw angular velocity can be reduced without reducing the vehicle wheel speed, thereby improving vehicle safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Shown is a schematic flow chart of a steering stability control method for an electric molten iron car in an embodiment of the present invention.

[0015] Figure 2 Shown is a diagram showing the calculation principle of distributing wheel torque in an embodiment of the present invention.

[0016] Figure 3 It is a schematic diagram showing the reverse steering of the rear wheels in an embodiment of the present invention.

[0017] Figure 4 It is a schematic diagram showing the vertical steering of the rear wheels in an embodiment of the present invention.

[0018] Figure 5 It is a schematic diagram showing the positive steering of the rear wheels in an embodiment of the present invention.

[0019] Figure 6Shown is a schematic diagram of a steering stability control system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0020] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0021] For example, when describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional view showing the device structure will not be partially enlarged according to the general scale, and the schematic view is only an example, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional space dimensions of length, width and depth should be included.

[0022] For ease of description, spatial relational terms such as "under", "below", "below", "below", "above", "on", etc. may be used herein to describe the relationship of one element or feature shown in the drawings to other elements or features. It will be understood that these spatial relational terms are intended to include other directions of the device in use or operation in addition to the directions depicted in the drawings. In addition, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or there can be one or more intervening layers. As used herein, "between..." means including the end point values.

[0023] In the context of the present application, a structure in which a first feature is described as being "above" a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

[0024] It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and therefore the illustrations only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0025] like Figure 1 As shown, electric molten iron cars are often used in steel mills to transport molten iron. In order to enable the electric molten iron car to maintain posture stability during the steering process and avoid slipping, this embodiment provides a steering stability control method for the electric molten iron car, and the steps of the method include:

[0026] S1. Obtain the slip rate and yaw rate of the vehicle.

[0027] When the vehicle is turning, if the slip ratio and yaw rate exceed the specified thresholds, the vehicle will become unstable during turning, resulting in situations such as skidding or rollover. By calculating the slip ratio and yaw rate of the vehicle, the attitude stability of the vehicle during turning can be understood. If the slip ratio and yaw rate of the vehicle do not reach the specified thresholds, it means that the vehicle can turn stably at this time; otherwise, adjustment is required to keep the vehicle stable during turning.

[0028] Both the slip ratio and yaw rate can be calculated using formulas, and then judgments can be made based on the calculation results. Among them, both the slip ratio and yaw rate need to be calculated through the rotational speeds of the wheels.

[0029] The steps to calculate the slip ratio of the vehicle are as follows: Monitor the rotational speeds of the driven wheels and driving wheels of the vehicle to obtain the actual speed and theoretical speed of the vehicle, and based on the actual speed and theoretical speed, obtain the slip ratio.

[0030] Among them, slip ratio = (theoretical wheel speed - actual wheel speed) / theoretical wheel speed × 100%. The theoretical speed of the wheel is obtained based on the rotational speed of the driving wheel, and the actual wheel speed is obtained based on the rotational speed of the driven wheel.

[0031] When obtaining the yaw rate using the formula calculation method, it is necessary to first monitor the rotational speeds of the inner wheels and outer wheels of the vehicle, the wheelbase of the wheels, and the wheel steering angle, and then calculate based on the yaw rate formula. It can be understood that when the vehicle turns to the left, the leftmost wheel of the vehicle is the inner wheel, and the rightmost wheel of the vehicle is the outer wheel. The wheelbase of the wheels is the distance between the inner wheel and the outer wheel, and the wheel steering angle is the angle by which the wheel deflects when the vehicle turns, usually referring to the angle turned by the front wheels of the vehicle. In addition, the yaw rate of the vehicle can also be directly obtained by using sensors.

[0032] To maintain the stability of the vehicle during turning, it is necessary to adjust both the slip ratio and yaw rate of the vehicle simultaneously. If, when the vehicle is turning, only the slip ratio is focused on for adjustment while ignoring the suppression of the vehicle's yaw rate, it is easy to produce phenomena such as excessive adjustment torque and excessive yaw rate.

[0033] S2. Determine the attitude stability adjustment based on the slip ratio and yaw rate.

[0034] After obtaining the slip ratio and yaw rate, it is necessary to make judgments on the slip ratio and yaw rate respectively. If the threshold of the slip ratio is S and the threshold of the yaw rate is A, compare the calculated slip ratio and yaw rate with the corresponding thresholds respectively. If the slip ratio < S and the yaw rate < A, it means that the attitude of the vehicle during turning is stable and no adjustment is required. Otherwise, the attitude stability of the vehicle needs to be adjusted.

[0035] S3. If posture stabilization adjustment is required, redistribute the torque of each wheel of the vehicle to reduce the slip rate.

[0036] Before redistributing the torque of each wheel of the vehicle, the contact pressure of each wheel must be calculated first, and then the wheel torque ratio on the coaxial line is calculated based on the contact pressure of each wheel, and then the torque of the wheels on the coaxial line is redistributed based on the wheel torque ratio.

[0037] like Figure 2 As shown, specifically, the mass of the vehicle body, the load mass, and the body inclination angle when the vehicle turns need to be collected when calculating the contact pressure of each wheel. When the vehicle is traveling in a straight line, the contact pressure of each wheel of the vehicle is obtained based on the mass of the vehicle body and the load mass through force analysis. When the vehicle turns, the body will tilt, and the degree of tilt of the body is represented by the collected body inclination angle. At this time, the load of each wheel of the vehicle will change, and then the body inclination angle is considered as a variable, and the contact pressure of each wheel is recalculated by force analysis.

[0038] The specific steps of calculating the wheel torque ratio on the same axis based on the contact pressure of each wheel are as follows: based on the recalculated contact pressure of each wheel, the contact pressure of the inner wheel and the outer wheel on the same axis are calculated to obtain the wheel torque ratio.

[0039] Due to the change in wheel load on both sides when turning, the contact pressure of the inner wheel is smaller than that of the outer wheel. If the same driving torque is still given to the wheels on both sides at this time, the inner wheel may slip. At this time, it is necessary to redistribute the torque to the inner and outer wheels based on the wheel torque ratio. If the wheel is a driving wheel, the driving torque of each wheel can be redistributed by changing the speed to reduce the possibility of slipping. If the wheel is a driven wheel, it is necessary to brake the driven wheel to redistribute the torque of each wheel.

[0040] When redistributing the torque of the wheels, the total torque of the wheels on the same axis remains unchanged, and the torque on a single wheel is redistributed according to the wheel torque ratio. For example, the total torque output by the vehicle to the drive wheels on the same axis is 50N·m. When the vehicle is traveling in a straight line, the inner and outer drive wheels on the same axis evenly distribute the total torque. If the contact pressure of the inner and outer drive wheels changes when turning, the torque to be distributed to the inner and outer drive wheels on the same axis is recalculated based on the total torque and the wheel torque ratio. It should be noted that if there are more than two drive wheels on the same axis, after calculating the torque to be distributed to the inner and outer drive wheels, the torque of other drive wheels can be calculated through force analysis. In this way, vehicle slippage can be effectively avoided by redistributing the torque of each wheel of the vehicle.

[0041] S4. Simultaneously, the rear wheels are independently controlled to steer according to the yaw angular velocity to assist the front wheels of the vehicle in steering.

[0042] like Figures 3 to 5 As shown, if the yaw rate exceeds the threshold, the problem of excessive yaw rate is adjusted at the same time. Here, the meaning of independently controlling the steering of the rear wheels of the vehicle means that the rear wheels of the vehicle can be steered, and the steering of the front wheels and the steering of the rear wheels can be controlled separately. The forms of rear wheel steering include reverse steering, vertical steering and same-direction steering. The reverse steering means that the steering of the rear wheels is opposite to the steering of the front wheels, the vertical steering means that the steering angle of the rear wheels is zero, and the same-direction steering means that the steering of the rear wheels is the same as the steering of the front wheels.

[0043] The steering adjustment of the rear wheels is based on the yaw rate. Specifically, the reverse steering, vertical steering and same-direction steering of the rear wheels correspond to the yaw rate from large to small, that is, if the yaw rate is large when the vehicle is turning, the rear wheels use reverse steering, and the turning radius R of the vehicle when turning will also be smaller; if the yaw rate is small when the vehicle is turning, the rear wheels use forward steering, and the turning radius R of the vehicle when turning will also be larger. In this way, the yaw rate of the vehicle is reduced by controlling the steering of the rear wheels. It should be noted that the yaw rate value that defines the forward and reverse steering of the rear wheels is determined according to the actual situation, and the steering angle of the rear wheels is also determined according to the actual situation.

[0044] like Figure 6 As shown, this embodiment discloses a steering stability control system, which uses the above method to control the stability of the vehicle. The system includes a wheel speed monitoring unit, a vehicle body tilt angle monitoring unit, a rear wheel steering unit, a wheel drive unit, a wheel brake unit and a control unit.

[0045] The wheel speed monitoring unit includes a plurality of speed sensors, which are used to monitor the wheel speed of each wheel; the vehicle body inclination monitoring unit includes a plurality of vehicle body inclination sensors, which are used to monitor the inclination changes of the vehicle body in the four directions of front, rear, left and right during the driving of the vehicle, and can be used to monitor the yaw rate of the vehicle; the rear wheel steering unit is used to independently adjust the steering of the rear wheels; the wheel drive unit is used to drive the driving wheels of the vehicle; the wheel brake unit is used to brake the driven wheels; the control unit calculates the slip rate and yaw rate of the vehicle based on the information collected by the wheel speed monitoring unit and the vehicle body inclination monitoring unit, and makes a posture stability adjustment judgment, the control unit controls the wheel drive unit to redistribute the driving torque to the driving wheels, controls the wheel brake unit to brake the driven wheels to redistribute the torque on the driven wheels, and controls the rear wheel steering unit to steer the rear wheels to assist the steering of the front wheels of the vehicle.

[0046] Specifically, the vehicle of this embodiment has 12 groups of wheels, 6 groups of front wheels and 6 groups of rear wheels, which are named as Group I wheels, Group II wheels, Group III wheels, Group IV wheels, Group V wheels and Group VI wheels respectively, among which Group II wheels and Group III wheels are driving wheels, and the remaining groups are driven wheels.

[0047] A speed sensor is respectively set at the wheels at the four end corners for monitoring, namely, the driven wheel group 1 and the driven wheel group 2 of the first group of wheels, and the driven wheel group 13 and the driven wheel group 16 of the VI group of wheels. The actual running speed of the vehicle can be obtained by monitoring the rotation speed of the four driven wheels.

[0048] For example, there are three body inclination sensors, which are respectively arranged at the front, middle and rear positions of the vehicle body, so as to monitor the inclination changes of the vehicle body in the four directions of front, back, left and right when the vehicle is driving. Obviously, the number of body inclination sensors can be set to be more.

[0049] The rear wheel steering unit includes three steering motors, which are used to control the steering of a group of wheels. When the rear wheels need to steer, the control unit sends a control instruction to each steering motor so that each steering motor drives the corresponding wheel to steer. Obviously, the number of steering motors can be set to be more.

[0050] Since the steering of the front wheels and rear wheels of the vehicle is independently controlled, the steering of the front wheels of this embodiment is controlled by a steering valve and a steering cylinder, wherein the steering valve is used to control the action of the steering cylinder, and the steering cylinder is used to control the steering of the front wheels. When the front wheels need to be steered, the control unit first controls the action of the steering valve, and then the steering valve controls the action of the steering cylinder, so that the front wheels turn left or right.

[0051] The wheel drive unit includes a motor drive (motor controller) and a wheel-side motor. Each driving wheel is driven by a wheel-side motor. The operation of each wheel-side motor is controlled by the motor drive. When the control unit sends a signal to the motor drive, the motor drive controls the operation of the wheel-side motor. Since each driving wheel has a wheel-side motor, it is convenient to control the operation of each driving wheel separately. In addition, the wheel-side motor 1 and the wheel-side motor 4 of the second group of wheels are respectively provided with a speed sensor for monitoring. By monitoring the rotation speed of the two driving wheels, the ideal running speed of the vehicle can be obtained.

[0052] The wheel brake unit includes a brake control module and various air valves. The working principle of the wheel brake unit is: the control unit sends a brake command to the brake control module, and the brake control module controls the air valves in each pipeline to brake the wheel.

[0053] In summary, the implementation process of this embodiment is as follows: when the vehicle is turning, if the slip rate and yaw rate of the vehicle exceed the threshold, the control unit will recalculate the torque to be distributed to each wheel, and then control the wheel brake unit and the wheel drive unit to brake the driven wheel and change the drive torque output to the drive wheel, so as to achieve the purpose of redistributing the torque. At the same time, the control unit will also control the operation of multiple steering motors to drive the corresponding driven wheels to turn, so as to make the rear wheels of the vehicle rotate in the reverse, vertical or forward direction, thereby reducing the yaw rate of the vehicle.

[0054] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for controlling the steering stability of an electric molten iron car, characterized in that: The steps of the method include: Obtain the slip rate and yaw rate of the vehicle; Perform attitude stability adjustment based on slip rate and yaw rate; If attitude stability adjustment is required, redistribute the torque of each wheel of the vehicle to reduce the slip rate; At the same time, the rear wheel steering is independently controlled according to the yaw angular velocity to assist the vehicle's front wheel steering.

2. The electric molten iron car steering stability control method according to claim 1, characterized in that: The step of calculating the slip rate of the vehicle is: monitoring the rotation speed of the driven wheels and the rotation speed of the driving wheels of the vehicle to obtain the actual speed and theoretical speed of the vehicle, and obtaining the slip rate based on the actual speed and the theoretical speed.

3. The electric molten iron car steering stability control method according to claim 1, characterized in that: The method of acquiring the yaw angular velocity includes formula calculation or sensor monitoring.

4. The electric molten iron car steering stability control method according to claim 1, characterized in that: Before redistributing the torque of each wheel of the vehicle, the contact pressure of each wheel must be calculated first, and then the wheel torque ratio on the coaxial line is calculated based on the contact pressure of each wheel, and then the torque of the wheels on the coaxial line is redistributed based on the wheel torque ratio.

5. The electric molten iron car steering stability control method according to claim 4, characterized in that: When calculating the contact pressure of each wheel, it is necessary to collect the mass of the vehicle body, the load mass, and the body inclination angle when the vehicle turns.

6. The electric molten iron car steering stability control method according to claim 4, characterized in that: The specific steps of calculating the wheel torque ratio on the same axis based on the contact pressure of each wheel are as follows: based on the recalculated contact pressure of each wheel, the contact pressure ratio of the inner wheel and the outer wheel on the same axis is calculated.

7. The electric molten iron car steering stability control method according to claim 1, characterized in that: The forms of rear wheel steering include reverse steering, vertical steering and same-direction steering. The reverse steering means that the steering of the rear wheels is opposite to that of the front wheels, the vertical steering means that the steering angle of the rear wheels is zero, and the same-direction steering means that the steering of the rear wheels is the same as that of the front wheels.

8. The electric molten iron car steering stability control method according to claim 7, characterized in that: The reverse steering, vertical steering and same-direction steering of the rear wheels correspond to the situations where the yaw angular velocity is from large to small.

9. A steering stability control system, characterized in that: include: A wheel speed monitoring unit, used to monitor the wheel speed of each wheel; The vehicle body tilt angle monitoring unit is used to monitor the changes in the vehicle body tilt angle during steering; Rear wheel steering unit, used to independently adjust the rear wheel steering; A wheel drive unit, used to drive the driving wheels of the vehicle; A wheel brake unit, used to brake the driven wheels of the vehicle; A control unit calculates the vehicle's slip rate and yaw rate based on the information collected by the wheel speed monitoring unit and the vehicle body inclination monitoring unit, and makes a posture stability adjustment judgment. The control unit is also used to control the wheel drive unit and the wheel brake unit to redistribute the drive torque to the drive wheels and the torque to the driven wheels, and control the rear wheel steering unit to steer the rear wheels to assist the steering of the front wheels of the vehicle.

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