Active and passive rollover safety system and method for electric tricycle

Abstract

The present invention discloses an active and passive safety system and method for an electric tricycle rollover. The active and passive safety system for an electric tricycle rollover includes an active safety device and a passive safety device. The active safety device includes two hydraulic rods arranged at the rear axle position of the electric tricycle, a tilt angle sensor arranged at the center axis position of the electric tricycle compartment, a yaw angle sensor and a controller arranged on the tricycle. When the electric tricycle body rolls over beyond a limit angle, the passive safety device is triggered, and the support rod is automatically expanded and pressed against the ground under the action of a lateral limit rod. At the same time, the lateral limit rod controls the expansion angle of the support rod to avoid serious injuries caused by rollover. The active and passive safety system and method for an electric tricycle rollover can improve the safety of the vehicle during driving and reduce the risk of rollover accidents.

Description

Technical Field

[0001] The present invention relates to the technical field of electric tricycles, and in particular to an active and passive rollover safety system and method for an electric tricycle. Background Art

[0002] In recent years, the online shopping industry has grown rapidly, and logistics infrastructure has continued to improve. According to data from the State Post Bureau, China's express delivery volume totaled 110.58 billion pieces in 2022, a 2.1% increase over the previous year; express delivery revenue totaled 1,056.67 billion yuan, a year-on-year increase of 2.3%. In this environment, electric tricycles have gradually become a key means of last-mile delivery. They are favored for their ease of use, lightweight and flexible design, and environmental friendliness.

[0003] However, compared to four-wheeled freight vehicles, electric tricycles still have some shortcomings. For example, due to their high center of gravity and low adhesion between the tires and the road, these vehicles have poor lateral stability during cornering, making them prone to rollover accidents when turning at high speeds, posing a potential safety hazard on the road. Therefore, safety designs tailored to these characteristics of electric tricycles are particularly important to ensure safety and reliability during cornering. Summary of the Invention

[0004] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid blurring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0005] Therefore, the purpose of the present invention is to provide an active and passive rollover safety system and method for an electric tricycle, so as to improve the safety of the vehicle during driving and reduce the risk of rollover accidents.

[0006] To solve the above technical problems, according to one aspect of the present invention, the present invention provides the following technical solutions:

[0007] An active and passive safety system for an electric tricycle rollover, comprising: an active safety device and a passive safety device;

[0008] The active safety device includes two hydraulic rods arranged on the rear axle of the electric tricycle, a tilt angle sensor arranged on the center axis of the electric tricycle, a yaw angle sensor arranged on the tricycle, and a controller;

[0009] The controller uses a control algorithm to adjust the hydraulic rod at the rear axle of the electric tricycle based on the two body stability parameters of the electric tricycle, namely the roll angle collected by the tilt angle sensor and the yaw angular velocity collected by the yaw angle sensor. When the electric tricycle body has a large roll angle, the axial force of the hydraulic rod is adjusted to provide an anti-roll torque Manti.

[0010] The passive safety device is configured to be triggered when the electric tricycle rolls over, and to deploy and support on the ground to prevent the electric tricycle body from hitting the ground due to the rollover.

[0011] As a preferred solution of the active and passive safety system for rollover of an electric tricycle described in the present invention, the coordinate system used when establishing the three-degree-of-freedom rollover model of the electric tricycle is specified with the following coordinate axes and positive directions: the origin of the coordinate system is the center of the electric tricycle, the driving direction of the electric tricycle is the positive direction of the X axis, the left direction perpendicular to the X axis and parallel to the ground is the positive direction of the Y axis, and the direction perpendicular to the ground and upward is the positive direction of the Z axis;

[0012] The equilibrium equation of the anti-roll moment Manti is:

[0013]

[0014] Among them, Ix is the moment of inertia of the vehicle around the X axis, is the roll angle of the sprung mass, ms is the sprung mass, ay is the lateral acceleration of the center of mass, h is the distance from the center of gravity of the sprung mass to the roll center, is the equivalent roll damping of the suspension, is the equivalent roll stiffness of the suspension.

[0015] As a preferred solution of the active and passive rollover safety system for an electric tricycle according to the present invention, the controller further includes a built-in sliding film controller. The sliding film controller adjusts the anti-roll torque provided by the hydraulic rod so that the roll angle of the electric tricycle can track the desired value. The sliding mode function of the sliding film controller is:

[0016]

[0017] Where c must satisfy the Hurwitz condition, so c is greater than 0, e is the tracking error, and we have:

[0018]

[0019] Using the exponential reaching law, we have:

[0020]

[0021] Combining equations (3) and (4), we get:

[0022]

[0023] Combining equations (1) and (5), we can obtain:

[0024]

[0025] As a preferred solution of the electric tricycle rollover active and passive safety system described in the present invention, the MPC control algorithm steps are as follows:

[0026] Get the current state parameter number x(k);

[0027] Optimize the robust performance function and obtain the control sequence u(kk),…,u(k+N-1 k);

[0028] Among them, the robust performance function is:

[0029]

[0030] stx k+1 =Ax k +Bu k +Gw k

[0031]

[0032] x k+N ∈X N (6)

[0033] Where, J N (x k+N ) is the terminal cost function, XN is the terminal constraint, and N is the prediction time domain;

[0034] Apply the first control variable u(kk) of the control sequence to the controlled object;

[0035] At the next moment, the state parameter x(k+1) is re-observed and the above steps are repeated to achieve continuous control of the controlled object.

[0036] As a preferred embodiment of the active and passive rollover safety system for an electric tricycle according to the present invention, the passive safety device comprises a support rod correspondingly mounted on both sides of the electric tricycle compartment and hinged at one end to the side of the electric tricycle compartment, and a lateral limit rod hinged at one end to the body of the electric tricycle and hinged at the other end to the middle of the support rod;

[0037] Among them, when the electric tricycle body rolls over and exceeds the limit angle, the passive safety device is triggered. At this time, the support rod is automatically expanded and pressed against the ground under the action of the lateral limit rod. At the same time, the lateral limit rod controls the expansion angle of the support rod to avoid serious injuries caused by rollover.

[0038] As a preferred solution of the electric tricycle rollover active and passive safety system described in the present invention, the lateral limiting rod is an electric telescopic rod.

[0039] Compared with the prior art, the present invention has the following beneficial effects: the present invention adopts an MPC control algorithm to adjust the hydraulic rod at the rear axle of the electric tricycle based on the two body stability parameters of the electric tricycle, namely the roll angle and yaw angular velocity. When the body has a large roll angle, the axial force of the hydraulic rod is adjusted to provide an anti-roll torque to correct the roll angle of the electric tricycle, so that the electric tricycle remains stable. In addition, in order to cope with the failure of the active safety device of the electric tricycle, a set of passive safety devices is provided. When the electric tricycle body rolls over beyond the limit angle, the passive safety device is triggered, and the support rod is automatically opened and pressed against the ground under the action of the lateral limit rod. At the same time, the lateral limit rod controls the deployment angle of the support rod to avoid serious injuries caused by rollover. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and detailed embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be derived from these drawings without inventive effort. Among them:

[0041] Figure 1 A system principle block diagram of the active safety device provided by the present invention;

[0042] Figure 2 This is a structural diagram of the installation of the active safety device electric tricycle and the hydraulic rod provided by the present invention;

[0043] Figure 3 A schematic structural diagram of the passive safety device provided by the present invention;

[0044] Figure 4 This is a block diagram of the EPS automatic steering controller provided by the present invention;

[0045] Figure 5 The rollover active control model built in Simulink provided by the present invention;

[0046] Figure 6 The vehicle roll tracking model built in Simulink provided by the present invention;

[0047] Figure 7 A schematic diagram of the step angle tracking control effect provided by the present invention;

[0048] Figure 8 A schematic diagram of the step angle tracking control error provided by the present invention;

[0049] Figure 9 A schematic diagram of the corner tracking control effect of the present invention;

[0050] Figure 10 A schematic diagram of the corner tracking control error in a curve condition provided by the present invention;

[0051] Figure 11 The roll angle response curve of the vehicle body without the sliding film controller provided by the present invention;

[0052] Figure 12 The roll angle response curve of the vehicle body with the sliding film controller provided by the present invention. DETAILED DESCRIPTION

[0053] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0054] Next, the present invention is described in detail with reference to schematic diagrams. For ease of illustration, cross-sectional views illustrating device structures may be partially enlarged and not to scale when describing the embodiments of the present invention. Furthermore, the schematic diagrams are merely illustrative and should not limit the scope of protection of the present invention. Furthermore, in actual production, three-dimensional dimensions, including length, width, and depth, should be included.

[0055] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0056] The present invention provides an active and passive rollover safety system and method for an electric tricycle, so as to improve the safety of the vehicle during driving and reduce the risk of rollover accidents.

[0057] Figure 1-Figure 3 The figure shows a schematic diagram of an electric tricycle rollover active and passive safety system of the present invention, see Figure 1-Figure 3 The electric tricycle rollover active and passive safety system includes an active safety device 100 and a passive safety device 200.

[0058] The active safety device 100 includes two hydraulic rods 110 arranged at the rear axle position of the electric tricycle H, a tilt angle sensor 120 arranged at the center axis position of the electric tricycle H, a yaw angle sensor 130 arranged on the tricycle 100, and a controller 140;

[0059] The controller 140 uses an MPC control algorithm to adjust the hydraulic rod 110 at the rear axle of the electric tricycle H based on the two body stability parameters of the electric tricycle, namely the roll angle collected by the tilt angle sensor 120 and the yaw angular velocity collected by the yaw angle sensor 130. When the electric tricycle H has a large roll angle, the axial force of the hydraulic rod 110 is adjusted to provide an anti-roll torque Manti.

[0060] The passive safety device 200 is configured to be triggered when the electric tricycle H rolls over, and to unfold and support the ground to prevent the body of the electric tricycle H from hitting the ground due to the rollover. The passive safety device 200 includes support rods 210 correspondingly installed on both sides of the electric tricycle H compartment and one end of which is hinged to the side of the electric tricycle H compartment, and a transverse limit rod 220 one end of which is hinged to the body of the electric tricycle H and the other end is hinged to the middle part of the support rod 210. When the body of the electric tricycle H rolls over beyond a limit angle, the passive safety device 200 is triggered. At this time, the support rod 210 is automatically expanded and pressed against the ground under the action of the transverse limit rod 220. At the same time, the transverse limit rod 220 controls the unfolding angle of the support rod 210 to avoid serious injuries caused by rollover. Preferably, the transverse limit rod 220 is an electric telescopic rod.

[0061] In this embodiment, the coordinate system used when establishing the three-degree-of-freedom rollover model of the electric tricycle H is specified with the following coordinate axes and positive directions: the origin of the coordinate system is the center of the electric tricycle H, the driving direction of the electric tricycle H is the positive direction of the X axis, the left direction perpendicular to the X axis and parallel to the ground is the positive direction of the Y axis, and the direction perpendicular to the ground and upward is the positive direction of the Z axis;

[0062] The equilibrium equation of the anti-roll moment Manti is:

[0063]

[0064] Among them, Ix is the moment of inertia of the vehicle around the X axis, is the roll angle of the sprung mass, ms is the sprung mass, ay is the lateral acceleration of the center of mass, h is the distance from the center of gravity of the sprung mass to the roll center, is the equivalent roll damping of the suspension, is the equivalent roll stiffness of the suspension.

[0065] The controller 140 further includes a built-in sliding mode controller 140a. The sliding mode controller 140a adjusts the anti-roll torque provided by the hydraulic rod 110 so that the roll angle of the electric tricycle H can track the desired value. The sliding mode function of the sliding mode controller 140a is:

[0066]

[0067] Among them, c must satisfy the Hurwitz condition, so c > 0, e is the tracking error, and there is:

[0068]

[0069] Using the exponential reaching law, there is:

[0070]

[0071] Combining equations (3) and (4), we get:

[0072]

[0073] Combining equations (1) and (5), we get: [[ID= twenty]]

[0074]

[0075] The steps of the MPC control algorithm are as follows:

[0076] Obtain the state parameter x(k) at the current moment;

[0077] Perform an optimal solution on the robust performance function to obtain the control sequence u(k|k), …, u(k + N - 1|k);

[0078] Among them, the robust performance function is:

[0079]

[0080] s.t. x k+1 = Ax k + Bu k + Gw k <00002**2>

[0082] x k+N ∈ X N (6)

[0083] In the formula, J N (x [[ID= sixty-three]] k+N ) is the terminal cost function, XN is the terminal constraint, and N is the prediction horizon;

[0084] Apply the first control quantity u(k|k) of the control sequence to the controlled object; <**000231>At the next moment, re-observe the state parameter x(k + 1), and repeat the above steps to achieve continuous control of the controlled object.

[0086] To verify the control effect of the active safety device 100 of the present invention, the following simulation test is provided: It should be noted that there are some unclear or incorrect expressions in the original text (such as "2**2" in the formula part), which may affect the accuracy of the translation. It is recommended to check and correct the original text for a more accurate translation.

[0087] Design an EPS corner tracking control strategy based on dual feedback. Referring to manned driving control, the EPS corner tracking control strategy includes two parts: the corner control loop and the current control loop. Dual feedback control is formed by corner feedback and current feedback, which is more conducive to EPS corner tracking than single closed-loop feedback control. Figure 4 The figure shows the block diagram of the EPS system's angle tracking control strategy, which mainly includes the angle control loop, the current control loop, and the controlled object. The controlled object is the EPS system. Considering the angle fluctuation of the EPS system during automatic steering, in order to reduce the impact of disturbances on control, the self-disturbance rejection control algorithm is used to design the angle feedback controller. The target angle determined by the controller and the steering wheel angle actually output by the EPS are used as inputs to output the target electric power assist torque. After the torque / current conversion, the target current is obtained. In order to accurately track the target current and improve the response speed of the motor, the sliding mode control algorithm is used to design the current feedback controller. In the torque / current conversion process, the difference from the dynamic model is that the motor output shaft parameter J m and B m Ignoring it, we can get T m =T a / G=k m I,, and finally get the target current

[0088] Build a simulink model such as Figure 5 and Figure 6 As shown, the double closed-loop tracking control simulation verification of the corner is carried out:

[0089] Based on the current tracking control, the angle is tracked in a closed loop. The angle deviation is input into the dual feedback controller, and the output is the motor terminal voltage. Then, the motor output torque Tm is obtained by combining the motor model conversion. In order to verify the angle tracking control effect of the dual closed loop feedback, the following is designed: Figure 7 As shown in the figure, the target steering wheel angle increases by 40 degrees every 5 seconds from 0 seconds to 10 seconds, increases by 80 degrees at 15 seconds, and increases to 160 degrees and maintains for 10 seconds. After that, it continuously decreases to -40 degrees and increases to 0 degrees after 5 seconds. The whole process includes positive and negative step increases of different amplitudes, as well as the situation where the steering wheel angle switches between positive and negative. Figure 8 is the corresponding angle tracking control error. Generally speaking, the tracking control effect is good, there is no tracking control overshoot, the adjustment time is kept at about 0.8s, and the response performance is good.

[0090] In order to further illustrate the effect of the angle tracking control, the target direction angle of the angle closed-loop control is turned to verify the angle tracking performance in the tracking control. Figure 9This is the effect diagram of the corner tracking control in the cornering condition. Figure 10 The figure shows the angle tracking control error for cornering conditions. Except for the initial state, where the tracking error is large, after the motor operates normally, the target angle and actual angle essentially coincide, with a small error. The maximum error occurs at 5.5s and 7.8s, where the target angle drops significantly and then quickly recovers. This is likely due to external disturbances. The tracking error is kept within 3.5 degrees, and there is no significant oscillation or overshoot. This indicates that the EPS angle tracking control is highly accurate in actual lane dynamic tracking control, effectively meeting the tracking control requirements.

[0091] In order to test the technical effect of adding the sliding membrane controller 140a to the present invention, the following simulation test is provided: when the vehicle turns with a lateral acceleration of 0.4g, its roll angle should be controlled within 2°-4.5°; when the vehicle turns with a lateral acceleration of 0.6g, its roll angle should be controlled within 6°.

[0092] The present invention considers a larger lateral acceleration, that is, a lateral acceleration of 0.6g for steering, and determines the ideal roll angle to be 5°. Assuming the front wheel angle step input is 10° and the vehicle longitudinal speed is 20km / h, the roll angle response curve of the tricycle is obtained as follows: Figure 11 , it can be seen that its peak reaches 8.5°, and the overall instability is large, and the overshoot is large. In this case, the handling stability of the tricycle is poor, which can easily cause psychological burden to the driver; after setting the sliding membrane controller, the response curve is as follows Figure 12 The control effect is stable and meets the expected set 5° roll angle.

[0093] In summary, this invention employs an MPC control algorithm to adjust the hydraulic levers at the rear axle of an electric tricycle based on two stability parameters: the vehicle's roll angle and yaw rate. This algorithm adjusts the axial force of the hydraulic levers to provide an anti-roll moment when the vehicle exhibits a large roll angle. Analysis of simulation results indicates that the MPC control method significantly improves the tricycle's rollover stability.

[0094] Although the present invention has been described above with reference to embodiments, various modifications may be made thereto and equivalent components may be substituted without departing from the scope of the present invention. In particular, as long as there are no structural conflicts, the various features of the embodiments disclosed herein may be combined with each other in any manner, and the omission of an exhaustive description of such combinations in this specification is solely for the sake of space and resource conservation. Therefore, the present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. An electric tricycle rollover active and passive safety system, characterized in that: include: Active safety device (100) and passive safety device (200); The active safety device (100) comprises two hydraulic rods (110) arranged at the rear axle position of the electric tricycle (H), a tilt angle sensor (120) arranged at the center axis position of the electric tricycle (H), a yaw angle sensor (130) arranged on the tricycle, and a controller (140); The controller (140) uses an MPC control algorithm to adjust a hydraulic rod (110) at the rear axle of the electric tricycle (H) based on two body stability parameters, namely, the roll angle of the electric tricycle acquired by the tilt angle sensor (120) and the yaw angular velocity acquired by the yaw angle sensor (130). When the electric tricycle (H) exhibits a large roll angle, the axial force of the hydraulic rod (110) is adjusted to provide an anti-roll moment Manti. The passive safety device (200) is configured to: be triggered when the electric tricycle (H) rolls over, and deploy and support on the ground to prevent the body of the electric tricycle (H) from hitting the ground due to the rollover; The coordinate system used when establishing the three-degree-of-freedom rollover model of the electric tricycle (H) is specified with the following coordinate axes and positive directions: the origin of the coordinate system is the center of the electric tricycle (H), the direction of travel of the electric tricycle (H) is the positive direction of the X-axis, the left direction perpendicular to the X-axis and parallel to the ground is the positive direction of the Y-axis, and the direction perpendicular to the ground and upward is the positive direction of the Z-axis. The equilibrium equation of the anti-roll moment Manti is: Among them, Ix is the moment of inertia of the vehicle around the X axis, is the roll angle of the sprung mass, ms is the sprung mass, ay is the lateral acceleration of the center of mass, h is the distance from the center of gravity of the sprung mass to the roll center, is the equivalent roll damping of the suspension, is the equivalent roll stiffness of the suspension; The controller (140) further includes a built-in sliding film controller (140a), wherein the sliding film controller (140a) adjusts the anti-roll torque provided by the hydraulic rod (110) so that the roll angle of the electric tricycle (H) can track a desired value. The sliding mode function of the sliding film controller (140a) is: Where c must satisfy the Hurwitz condition, so c is greater than 0, e is the tracking error, and we have: Using the exponential reaching law, we have: Combining equations (3) and (4), we get: Combining equations (1) and (5), we can obtain: The MPC control algorithm steps are as follows: Get the current state parameter x(k); Optimize the robust performance function and obtain the control sequence u(kk),…,u(k+N-1k); Among them, the robust performance function is: st x k+1 =Ax k + There was k + See k x k+N ∈X N (6) Where, J N (x k+N ) is the terminal cost function, XN is the terminal constraint, and N is the prediction time domain; Apply the first control variable u(kk) of the control sequence to the controlled object; At the next moment, the state parameter x(k+1) is re-observed and the above steps are repeated to achieve continuous control of the controlled object.

2. The electric tricycle rollover active and passive safety system according to claim 1, characterized in that: The passive safety device (200) comprises a support rod (210) correspondingly mounted on both sides of the electric tricycle (H) compartment and hinged at one end to the side of the electric tricycle (H) compartment, and a transverse limiting rod (220) hinged at one end to the body of the electric tricycle (H) and hinged at the other end to the middle of the support rod (210); When the electric tricycle (H) rolls over beyond a limit angle, the passive safety device (200) is triggered. At this time, the support rod (210) is automatically spread out under the action of the transverse limit rod (220) and pressed against the ground. At the same time, the transverse limit rod (220) controls the expansion angle of the support rod (210) to avoid serious damage caused by rollover.

3. The electric tricycle rollover active and passive safety system according to claim 2, characterized in that: The transverse limiting rod (220) is an electric telescopic rod.

4. A method and steps for an electric tricycle rollover active and passive safety system according to any one of claims 1 to 3, characterized in that: The specific steps are as follows: S1. During the driving of the electric tricycle (H), the yaw angle sensor (130) and the tilt angle sensor (120) of the active safety device (100) monitor the yaw angle and the roll angle of the electric tricycle (H) in real time and transmit the information to the controller (140). The controller (140) adjusts the hydraulic rod (110) at the rear axle of the electric tricycle (H) according to the received yaw angle and the roll angle. When the body of the electric tricycle (H) has a large roll angle, the axial force of the hydraulic rod (110) is adjusted to provide an anti-roll moment Manti. S2. When the active safety device (100) is unable to correct the roll angle of the electric tricycle (H) and causes the electric tricycle (H) to roll over beyond the limit angle, the passive safety device (200) is triggered. At this time, the support rod (210) is automatically spread out under the action of the lateral limit rod (220) and pressed against the ground. At the same time, the lateral limit rod (220) controls the expansion angle of the support rod (210) to avoid serious damage caused by rollover.

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