A method and system for emergency control of high-speed tire blowout of intelligent vehicle

Abstract

The present invention discloses a method and system for emergency control of high-speed tire blowout of an intelligent vehicle, the method comprising the following steps: step 1, determining whether a tire blowout occurs and the location of the tire blowout; step 2, calculating the compensation torque required to maintain vehicle stability, and calculating the distribution coefficient of the braking torque required for each wheel to achieve vehicle deceleration; step 3, planning one or more lane change trajectories according to a planning method. The present invention can effectively improve the safety of deceleration in the case of a tire blowout.

Description

Technical Field

[0001] The present invention relates to the field of unmanned driving technology, and in particular to a method and system for emergency control of high-speed tire blowout of an intelligent vehicle. Background Art

[0002] At present, the integration and development of electric, intelligent and networked automobiles is accelerating. Smart cars have become the largest emerging mobile intelligent terminals, and at the same time they bear the main task of supporting the construction of intelligent transportation and smart cities. As the most common means of transportation in life, safety is one of the main factors affecting the development of smart cars. Among them, tire blowouts have always been the main source of serious traffic accidents. After a tire blowout, the rolling radius of the tire decreases, and the vehicle load is redistributed, causing the vehicle to yaw. For high-level smart cars, since the system completely replaces the operation of human drivers, the initiative of the car is in the control system of the smart car. Therefore, reasonable emergency control after a tire blowout will be related to the personal safety of many passengers.

[0003] China's invention patent publication number CN214823224U discloses an intelligent processing system and control method for dealing with sudden tire blowouts of automobiles, including an ECU controller, a TPMS receiver, a steering wheel torque sensor, a throttle position sensor, a vehicle speed sensor, an alarm signal light, an injection control system, an intelligent braking system, and an intelligent steering wheel stability system. This technical solution locks the steering wheel when a tire blowout occurs, controls the braking system to perform point braking, and achieves stability control of the tire blowout vehicle. Its disadvantage is that it does not distinguish the tire blowout position of the wheel and directly performs point braking. The rolling resistance coefficient rises rapidly after the tire blows out. At this time, braking the tire blowout wheel will cause greater yaw.

[0004] The above-mentioned published content also does not involve high-speed driving environments. The consequences of a tire blowout at high speed and low speed are completely different. Therefore, how to solve the safety control method of tire blowout in smart vehicles during high-speed driving is a technical difficulty that needs to be overcome to improve the safety factor of smart vehicles. Summary of the invention

[0005] The purpose of the present invention is to provide a method for emergency control of high-speed tire blowout of an intelligent vehicle in view of the technical defects in the prior art.

[0006] Another object of the present invention is to provide an intelligent system for emergency control of high-speed tire blowout of a car.

[0007] The technical solution adopted to achieve the purpose of the present invention is:

[0008] A method for emergency control of a high-speed tire blowout of an intelligent vehicle comprises the following steps:

[0009] Step 1: Determine whether a tire blowout occurs and where the tire blowout occurs:

[0010] Set normal and extreme thresholds for tire pressure and temperature. If the normal threshold is exceeded, it is considered as a tire abnormality. Continue to monitor pressure and temperature. If the normal threshold is exceeded, it is considered as a tire blowout and the location of the blowout is determined by combining the proportional coefficient of the rotation speed of each wheel.

[0011] Step 2, calculating the compensation torque required to maintain vehicle stability and calculating the distribution coefficient of the braking torque required for each wheel to achieve vehicle deceleration, specifically including the following steps:

[0012] Step 2.1 Calculate the actual center of mass sideslip angle of the vehicle;

[0013] Step 2.2 calculates the difference between the actual yaw rate and the sideslip angle of the center of mass and the ideal yaw rate and the ideal sideslip angle of the center of mass of the ideal two-degree-of-freedom vehicle dynamics model, and uses the fuzzy control algorithm to obtain the compensation torque required to maintain the stability of the vehicle;

[0014] Step 2.3: Calculate the change in the vertical load of the wheel according to the lateral acceleration and the effective rolling radius of the tire-bursting wheel, and calculate the real-time compensation torque distribution coefficient of the wheel at each position according to the change in the vertical load of the wheel;

[0015] By controlling the braking system to apply corresponding braking torques to tires at different positions to overcome the yaw torque caused by a tire blowout, the vehicle can be decelerated while ensuring vehicle stability.

[0016] Step 3: Plan one or more lane change trajectories according to the planning method:

[0017] The system determines the lane the vehicle is in based on vehicle and environmental information, detects whether the right lane is an emergency lane and whether there are other vehicles, plans the lane change path based on a fifth-order polynomial and monitors environmental vehicle information in real time. When the vehicle speed drops to a predetermined value, the right lane is not an emergency lane and there are no other vehicles, the steering system executes the first lane change; when the right lane is an emergency lane and there are no other vehicles, the steering system executes the last lane change.

[0018] In the above technical solution, in step 1, the proportional coefficients of the rotation speed of each wheel are defined as P and Q:

[0019]

[0020] where ω i (i=1,2,3,4) represents the wheel angular velocity of the left front wheel, right front wheel, left rear wheel and right rear wheel respectively. The positive or negative value of the proportional factor P determines whether the tire blowout occurs on the front axle or the rear axle. The positive or negative value of the proportional factor Q determines whether the tire blowout occurs on the left or right side. The wheel position where the tire blowout occurs can be determined by combining P and Q.

[0021] In the above technical solution, in step 2.1, the actual center of mass sideslip angle calculation formula is as follows:

[0022]

[0023] Where m is the mass of the car, a and b are the distances from the front and rear axles to the center of mass, k2 is the rear wheel cornering stiffness, all of which are known vehicle parameters. x is the longitudinal velocity of the vehicle measured by the sensor, γ is the actual yaw rate of the vehicle measured by the sensor, and β is the actual sideslip angle of the center of mass.

[0024] In the above technical solution, in step 2.2, the ideal yaw angular velocity γ d Side slip angle β with ideal center of mass d The calculation formula is as follows:

[0025]

[0026]

[0027] Where m is the mass of the vehicle, k1 and k2 are the cornering stiffness of the front and rear axles, a and b are the distances from the front and rear axles to the center of mass, and I Z is the moment of inertia of the vehicle around the Z axis, μ is the road adhesion coefficient, g is the acceleration due to gravity, The above are all known vehicle parameters, δ is the front wheel angle measured by the sensor, v x 、v y are the longitudinal velocity and lateral velocity of the vehicle measured by the sensor, sgn(x) is the sign function;

[0028] Then △β=(β-β d ), △γ=(γ-γ d ).

[0029] In the above technical solution, in step 2.3, the calculation formula for the change in the vertical load of the wheel is as follows:

[0030]

[0031] Among them, F zi (i=1,2,3,4) is the vertical load on the wheel, F C is the vertical load variation, R b is the effective rolling radius after the tire bursts, and the suspension stiffness of the four wheels is K s .

[0032] In the above technical solution, in step 2.3, the real-time compensation torque distribution coefficient of the wheel at each position is calculated according to the change in the vertical load of the wheel, as shown in the following formula:

[0033]

[0034] where k b , k c , k i , k d They represent the compensation torque distribution coefficients of the tire-bursting wheel, the wheel coaxial with the tire-bursting wheel, the wheel on the same side of the tire-bursting wheel, and the wheel diagonal to the tire-bursting wheel, respectively. zc 、F zi 、F zd They respectively represent the vertical loads corresponding to the coaxial wheel with the flat tire, the wheel on the same side of the flat tire, and the wheel diagonal to the flat tire.

[0035] In the above technical solution, in step 3, the quintic polynomial equation is:

[0036]

[0037] where y e is the lateral displacement at the end of lane change, i.e., the width from the current position to the center of the right lane, t is the lane change time, t e The lane change end time.

[0038] In the above technical solution, in step 3, after the lane change is completed, the edge of the road is detected and the vehicle starts braking to stop, and the driver is reminded to move to a safe area and wait through the human-computer interaction screen.

[0039] In another aspect of the present invention, an emergency control system for a high-speed tire blowout of an intelligent vehicle comprises: a data acquisition layer, a control planning layer, and a strategy execution layer;

[0040] The data acquisition layer is mainly responsible for receiving vehicle and environment information uploaded from the lower layer sensors, and collating the information and uploading it to the control planning layer;

[0041] The control planning layer is mainly responsible for receiving the information uploaded by the data acquisition layer for processing, formulating and sending the control strategy to the strategy execution layer; the control planning layer formulates the control strategy according to the method as claimed in claim 1;

[0042] The strategy execution layer is mainly responsible for receiving the control strategy of the control planning layer.

[0043] In the above technical solution, the lower layer sensors include tire pressure and temperature sensors, wheel speed sensors, vehicle speed sensors, acceleration sensors, tire angular acceleration sensors, yaw rate sensors, front wheel angle sensors, cameras, ultrasonic radars, and millimeter wave radars;

[0044] The vehicle and environment information includes real-time tire internal pressure, real-time tire internal temperature, vehicle longitudinal speed, vehicle lateral speed, vehicle longitudinal acceleration, vehicle lateral acceleration, wheel speed, wheel angular velocity, yaw angular velocity, front wheel turning angle, lane line information, vehicle position on the road, and nearby vehicle position and speed;

[0045] The control actuator performs tire blowout stability control; the actuator includes a human-machine interaction screen, a wire-controlled steering mechanism, a wire-controlled braking mechanism, an on-board computer, and a drive motor.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] 1. The sensors involved in the control system of the present invention are all normal vehicle configurations, which greatly reduces the production cost of smart vehicles while ensuring safety control;

[0048] 2. The present invention determines the braking torque of each wheel by utilizing the transfer amount of wheel load after a tire burst, and can dynamically adjust the torque size, thereby ensuring that the intelligent vehicle can achieve safe deceleration under the premise of stabilizing the original driving path;

[0049] 3. After completing safe deceleration, the present invention further plans a lane change trajectory and realizes parking in the emergency lane under the state of low-speed driving to ensure the personal safety of the occupants. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 is a flow chart of the control system execution of the present invention;

[0051] Figure 2 This is a schematic diagram of the yaw and compensation torque after a vehicle tire bursts, and the left front tire bursts;

[0052] Figure 3 is a schematic diagram of lane change trajectory planning, showing multiple lane changes;

[0053] Figure 4 is a schematic diagram of parameters of a lane changing process in one embodiment of the present invention;

[0054] Figure 5 It is a three-dimensional graph of the membership function of fuzzy control. DETAILED DESCRIPTION

[0055] The present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0056] When the smart vehicle was driving at high speed, the left front wheel was punctured by a foreign object, causing the tire pressure to change and eventually the tire strength exceeded the limit and caused a tire blowout.

[0057] The tire pressure and temperature sensor monitors in real time that the pressure and temperature inside the tire rise rapidly from normal values ​​and exceed the normal threshold, and determines that there is an abnormality with the tire. The intelligent vehicle tire blowout stability control system starts to intervene in system control from standby mode, and reminds the driver of the tire abnormality through the human-computer interaction screen.

[0058] The tire pressure rises to the limit value and then suddenly turns into atmospheric pressure. The temperature inside the tire continues to rise and then drops rapidly. It is determined that a tire blowout has occurred. The control planning layer determines the location of the tire blowout based on the proportional coefficient of the wheel speed and reminds the driver of the tire blowout through the human-computer interaction screen. The intelligent vehicle tire blowout stability control system begins control planning.

[0059] Example 1

[0060] A method for emergency control of a high-speed tire blowout of an intelligent vehicle comprises the following steps:

[0061] Step 1, determine whether a tire blowout occurs and the location where the tire blowout occurs.

[0062] Set normal and extreme thresholds for tire pressure and temperature. If the normal threshold is exceeded, it is considered as a tire abnormality. Continue to monitor pressure and temperature. If the normal threshold is exceeded, it is considered as a tire blowout and the location of the blowout is determined by combining the proportional coefficient of each wheel speed. The specific determination method is as follows:

[0063] Define the proportional coefficients of each wheel speed as P and Q:

[0064]

[0065] where ω i (i=1,2,3,4) represents the wheel angular velocity of the left front wheel, right front wheel, left rear wheel and right rear wheel respectively. The positive or negative value of the proportional factor P determines whether the tire blowout occurs on the front axle or the rear axle. The positive or negative value of the proportional factor Q determines whether the tire blowout occurs on the left or right side. The wheel position where the tire blowout occurs can be determined by combining P and Q.

[0066] Step 2, calculating the compensation torque required to maintain vehicle stability and calculating the distribution coefficient of the braking torque required for each wheel to achieve vehicle deceleration, specifically including the following steps:

[0067] Step 2.1 Calculate the actual center of mass sideslip angle of the vehicle;

[0068] The actual center of mass sideslip angle calculation formula is as follows:

[0069]

[0070] Where m is the mass of the car, a and b are the distances from the front and rear axles to the center of mass, k2 is the rear wheel cornering stiffness, all of which are known vehicle parameters. xis the longitudinal velocity of the vehicle measured by the sensor, γ is the actual yaw rate of the vehicle measured by the sensor, and β is the actual sideslip angle of the center of mass.

[0071] Step 2.2 calculates the difference between the actual yaw rate and the sideslip angle of the center of mass and the ideal yaw rate and the ideal sideslip angle of the center of mass of the ideal two-degree-of-freedom vehicle dynamics model, and uses the fuzzy control algorithm to obtain the compensation torque required to maintain the stability of the vehicle;

[0072] Ideal yaw rate γ d Side slip angle β with ideal center of mass d The calculation formula is as follows:

[0073]

[0074]

[0075] Where m is the mass of the vehicle, k1 and k2 are the cornering stiffness of the front and rear axles, a and b are the distances from the front and rear axles to the center of mass, and I Z is the moment of inertia of the vehicle around the Z axis, μ is the road adhesion coefficient, g is the acceleration due to gravity, The above are all known vehicle parameters, δ is the front wheel angle measured by the sensor, v x 、v y are the longitudinal velocity and lateral velocity of the vehicle measured by the sensor respectively, and sgn(x) is the sign function.

[0076] Then △β=(β-β d ), △γ=(γ-γ d ).

[0077] Then, according to △β and △γ, the compensation torque required to maintain vehicle stability is obtained by using fuzzy control algorithm. The three-dimensional graph of the membership function of fuzzy control is as follows: Figure 5 shown.

[0078] Step 2.3: Calculate the change in the vertical load of the wheel based on the lateral acceleration and the effective rolling radius of the tire-bursting wheel, and calculate the real-time compensation torque distribution coefficient of the wheel at each position based on the change in the vertical load of the wheel.

[0079] The calculation formula for the change in wheel vertical load is as follows:

[0080]

[0081] Among them, F zi (i=1,2,3,4) is the vertical load on the wheel, F C is the vertical load variation, R b is the effective rolling radius after the tire bursts, and the suspension stiffness of the four wheels is K s .

[0082] The real-time compensation torque distribution coefficient of each wheel position is calculated according to the change in the vertical load of the wheel, as shown in the following formula:

[0083]

[0084] where k b , k c , k i , k d They represent the compensation torque distribution coefficients of the tire-bursting wheel, the wheel coaxial with the tire-bursting wheel, the wheel on the same side of the tire-bursting wheel, and the wheel diagonal to the tire-bursting wheel, respectively. zc 、F zi 、F zd They respectively represent the vertical loads corresponding to the coaxial wheel with the flat tire, the wheel on the same side of the flat tire, and the wheel diagonal to the flat tire.

[0085] By controlling the braking system to apply corresponding braking torque to tires in different positions to overcome the yaw moment caused by a tire blowout, the vehicle can be decelerated while ensuring vehicle stability.

[0086] Step 3: Plan one or more lane change trajectories according to the planning method:

[0087] According to the vehicle and environment information, the vehicle is determined to be in the same lane, whether the right lane is an emergency lane and whether there are other vehicles. The lane change path is planned based on the fifth-order polynomial and the vehicle information of the environment is monitored in real time. When the vehicle speed drops to 30 km / h, the right lane is not an emergency lane and there are no other vehicles, the steering system performs the first lane change; when the right lane is an emergency lane and there are no other vehicles, the steering system performs the last lane change. The fifth-order polynomial equation is:

[0088]

[0089] where y e is the lateral displacement at the end of lane change, i.e., the width from the current position to the center of the right lane, t is the lane change time, t e The lane change end time.

[0090] After the lane change is completed, the system detects the edge of the road and starts braking to stop the vehicle, and reminds the driver to move to a safe area and wait through the human-computer interaction screen.

[0091] Example 2

[0092] An intelligent automobile high-speed tire blowout emergency control system, comprising: a data acquisition layer, a control planning layer, and a strategy execution layer;

[0093] The smart car is a four-wheel drive electric car built on a wire-controlled chassis;

[0094] The data acquisition layer is mainly responsible for receiving the vehicle and environment information uploaded from the lower layer sensors, and uploading the information to the control planning layer after collating the information; the lower layer sensors include tire pressure and temperature sensors, wheel speed sensors, vehicle speed sensors, acceleration sensors, tire angular acceleration sensors, yaw rate sensors, front wheel angle sensors, cameras, ultrasonic radars, and millimeter wave radars; the vehicle and environment information includes real-time pressure inside the tire, real-time temperature inside the tire, vehicle longitudinal speed, vehicle lateral speed, vehicle longitudinal acceleration, vehicle lateral acceleration, wheel speed, wheel angular velocity, yaw rate, front wheel angle, lane line information, vehicle position on the road, and nearby vehicle position and speed;

[0095] The control planning layer is mainly responsible for receiving and processing the information uploaded by the data acquisition layer, formulating and sending the control strategy to the strategy execution layer; the control planning layer formulates the control strategy according to the method described in Example 1.

[0096] The strategy execution layer is mainly responsible for receiving the control strategy of the control planning layer and controlling the execution mechanism to perform tire blowout stability control; the execution mechanism includes a human-computer interaction screen, a wire-controlled steering mechanism, a wire-controlled braking mechanism, an on-board computer, and a drive motor.

[0097] When a tire blowout is confirmed, the strategy execution layer controls the on-board computer to turn on the hazard lights and uploads the tire blowout information to the management platform through the V2V system, alerting other nearby vehicles to avoid the tire.

[0098] The strategy execution layer cuts off the power supply to the drive motor of the wire-controlled chassis;

[0099] The strategy execution layer cuts off the signal input from the steering wheel and brake pedal to ensure that the vehicle will not cause greater danger due to misoperation caused by excessive driver tension.

[0100] The above is only a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for emergency control of a high-speed tire blowout of an intelligent vehicle, characterized in that: The following steps are involved: Step 1: Determine whether a tire blowout occurs and where the tire blowout occurs: Set normal and extreme thresholds for tire pressure and temperature. If the normal threshold is exceeded, it is considered as a tire abnormality. Continue to monitor pressure and temperature. If the normal threshold is exceeded, it is considered as a tire blowout and the location of the blowout is determined by combining the proportional coefficient of the rotation speed of each wheel. Step 2, calculating the compensation torque required to maintain vehicle stability and calculating the distribution coefficient of the braking torque required for each wheel to achieve vehicle deceleration, specifically including the following steps: Step 2.1 Calculate the actual center of mass sideslip angle of the vehicle; Step 2.2 calculates the difference between the actual yaw rate and the sideslip angle of the center of mass and the ideal yaw rate and the ideal sideslip angle of the center of mass of the ideal two-degree-of-freedom vehicle dynamics model, and uses the fuzzy control algorithm to obtain the compensation torque required to maintain the stability of the vehicle; Step 2.3: Calculate the change in the vertical load of the wheel according to the lateral acceleration and the effective rolling radius of the tire-bursting wheel, and calculate the real-time compensation torque distribution coefficient of the wheel at each position according to the change in the vertical load of the wheel; By controlling the braking system to apply corresponding braking torques to tires at different positions to overcome the yaw torque caused by a tire blowout, the vehicle can be decelerated while ensuring vehicle stability. In step 2.3, the calculation formula for the change in the vertical load of the wheel is as follows: Among them, F zi (i=1,2,3,4) is the vertical load on the wheel, F C is the vertical load variation, R b is the effective rolling radius after the tire bursts, and the suspension stiffness of the four wheels is K s ; In step 2.3, the real-time compensation torque distribution coefficient of the wheels at each position is calculated according to the change in the vertical load of the wheels, as shown in the following formula: where k b , k c , k i , k d They represent the compensation torque distribution coefficients of the tire-bursting wheel, the wheel coaxial with the tire-bursting wheel, the wheel on the same side of the tire-bursting wheel, and the wheel diagonal to the tire-bursting wheel, respectively. zc 、F zi 、F zd They represent the vertical loads corresponding to the coaxial wheel of the tire bursting wheel, the wheel on the same side of the tire bursting wheel, and the wheel diagonal to the tire bursting wheel respectively; Step 3: Plan one or more lane change trajectories according to the planning method: The system determines the lane the vehicle is in based on vehicle and environmental information, detects whether the right lane is an emergency lane and whether there are other vehicles, plans the lane change path based on a fifth-order polynomial and monitors environmental vehicle information in real time. When the vehicle speed drops to a predetermined value, the right lane is not an emergency lane and there are no other vehicles, the steering system executes the first lane change; when the right lane is an emergency lane and there are no other vehicles, the steering system executes the last lane change.

2. The method for emergency control of high-speed tire blowout of an intelligent vehicle as claimed in claim 1, characterized in that: In step 1, the proportional coefficients of the rotation speed of each wheel are defined as P and Q: where ω i (i=1,2,3,4) represents the wheel angular velocity of the left front wheel, right front wheel, left rear wheel and right rear wheel respectively. The positive or negative value of the proportional coefficient P determines whether the tire blowout occurs on the front axle or the rear axle. The positive or negative value of the proportional coefficient Q determines whether the tire blowout occurs on the left or right side. The wheel position where the tire blowout occurs can be determined by combining P and Q.

3. The method for emergency control of high-speed tire blowout of an intelligent vehicle as claimed in claim 1, characterized in that: In step 2.1, the actual center of mass sideslip angle calculation formula is as follows: Where m is the mass of the car, a and b are the distances from the front and rear axles to the center of mass, k2 is the rear wheel cornering stiffness, all of which are known vehicle parameters. x is the longitudinal velocity of the vehicle measured by the sensor, γ is the actual yaw rate of the vehicle measured by the sensor, and β is the actual sideslip angle of the center of mass.

4. The method for emergency control of high-speed tire blowout of an intelligent vehicle as claimed in claim 1, characterized in that: In step 3, the fifth-order polynomial equation is: where y e is the lateral displacement at the end of lane change, i.e., the width from the current position to the center of the right lane, t is the lane change time, t e The lane change end time.

5. The method for emergency control of high-speed tire blowout of an intelligent vehicle as claimed in claim 1, characterized in that: In step 3, after the lane change is completed, the road edge is detected and the vehicle starts braking to stop, and the driver is reminded to move to a safe area and wait through the human-computer interaction screen.

6. An emergency control system for a high-speed tire blowout of an intelligent vehicle, characterized in that: include: Data acquisition layer, control planning layer, and strategy execution layer; The data acquisition layer is responsible for receiving vehicle and environment information uploaded from the lower layer sensors, and collating the information and uploading it to the control planning layer; The control planning layer is responsible for receiving the information uploaded by the data acquisition layer for processing, formulating and sending the control strategy to the strategy execution layer; the control planning layer formulates the control strategy according to the method as claimed in claim 1; The strategy execution layer is responsible for receiving the control strategy of the control planning layer.

7. The emergency control system for high-speed tire blowout of an intelligent vehicle as claimed in claim 6, characterized in that: The lower layer sensors include tire pressure and temperature sensors, wheel speed sensors, vehicle speed sensors, acceleration sensors, tire angular acceleration sensors, yaw rate sensors, front wheel angle sensors, cameras, ultrasonic radars, and millimeter wave radars; The vehicle and environment information includes real-time tire internal pressure, real-time tire internal temperature, vehicle longitudinal speed, vehicle lateral speed, vehicle longitudinal acceleration, vehicle lateral acceleration, wheel speed, wheel angular velocity, yaw angular velocity, front wheel turning angle, lane line information, vehicle position on the road, and nearby vehicle position and speed; The control actuator performs tire blowout stability control; the actuator includes a human-machine interaction screen, a wire-controlled steering mechanism, a wire-controlled braking mechanism, an on-board computer, and a drive motor.

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