CN107351822B - A kind of safety guarantee method of four-wheel electric vehicle - Google Patents

Abstract

The invention provides a safety guarantee method for a four-wheel electric vehicle, comprising the following steps: S1, real-time detection of the position of the pedals, real-time detection of the vehicle speed v1 and calculation of the real-time acceleration a of the vehicle, and sequentially dividing the entire stroke of the pedals from large to small It is a mechanical braking area, a variable speed area and an electronic braking area. S2. Control the first ultrasonic sensor to emit a section of ultrasonic waves, and start timing at the same time. The time is t. The first ultrasonic sensor closes the echo detection, and the second ultrasonic sensor enters the echo detection state; The safety assurance method of this four-wheel electric vehicle relies on ultrasonic sensors to detect obstacles in front, and reasonably controls the braking system of the vehicle according to the distance between the obstacle and the vehicle, the position of the pedal, the vehicle speed, the acceleration and other states, and effectively guarantees the safety of the vehicle. and driver safety.

Description

A kind of safety guarantee method of four-wheel electric vehicle

technical field

The invention relates to the technical field of four-wheel electric vehicles, in particular to a safety guarantee method for four-wheel electric vehicles.

Background technique

The rising number of cars has raised a series of problems. Most cars burn fossil fuels such as gasoline, diesel, and natural gas. The reserves of fossil fuels on the earth are limited, and the huge and increasing number of cars makes the energy crisis increasingly serious. The weight of a traditional car is generally about 1500kg, and the payload is only about 100kg. Most of the energy is wasted on the invalid load, resulting in serious energy waste. In addition, traditional cars are bulky, and the average car covers an area of about 10 square meters. The increase in the number of cars has made the problems of traffic congestion and parking spaces more and more serious.

In recent years, electric vehicles have been welcomed by more and more consumers. The price of electric vehicles is lower than that of traditional cars, and the cost of charging electric vehicles is also lower than that of refueling cars; electric vehicles are flexible and compact, and generally do not encounter traffic jams when driving on non-motorized lanes, and it is easier to find parking spaces; The car has no exhaust emissions and will not pollute the environment.

The Chinese patent with the publication number CN104554199A and the publication date of 2015.4.29 discloses a single-pedal speed control system for electric vehicles, including a speed control pedal, a pedal position sensor, a speed controller, a brake valve and a return spring; only one The pedal realizes the starting, acceleration, constant speed driving, deceleration and braking process of the electric vehicle; the pedal travel is divided into two areas, the upper area is the speed adjustment area, and the lower area is the braking area. When the pedal is in the braking area , the pedal directly acts on the brake valve through the pedal force through the connecting rod. When the pedal is in the speed regulation area, the pedal is separated from the brake valve. The initial position of the pedal is at the top of the speed adjustment area. When the pedal is pressed with the foot, the pedal gradually moves to the braking area. When the pedal is completely released, the pedal returns to the initial position. The single-pedal speed control system of this electric vehicle uses a speed control pedal to replace the accelerator and brake pedals controlled by traditional vehicles. The complexity of the vehicle eliminates the possibility of misoperation and facilitates quick mastery of driving skills.

The publication number is CN106627173A, and the Chinese patent whose publication date is 2017.05.10 provides an intelligent control method for a four-wheel electric vehicle. The pedals of the four-wheel electric vehicles controlled are also single pedals, and the strokes of the pedals are arranged in order from large to small. It is divided into mechanical brake area, speed change area and electronic brake area. Specifically, 0-10% of the stroke is the mechanical brake area, 10-90% of the stroke is the speed change area, and 90-100% of the stroke is the electronic brake area. It is connected with the hydraulic brake, and the hydraulic brake acts as a mechanical brake. When the pedal is in the mechanical braking area, the hydraulic brake brakes the brake disc; the speed change area is the area for providing power and maintaining speed, and the electronic braking area is the area for starting the electronic brake. The vehicle controller controls the motor controller to output a reverse current, so that the motor generates a magnetic torque opposite to the rolling direction of the tire to brake the tire. Because this electric car does not have a hand brake, it is easy to slip when parking on a ramp. In the present invention, an electromagnetic brake is used to replace the hand brake. The electromagnetic brake is installed on the motor shaft, and a 48v power supply is used. The power supply of the electromagnetic brake is controlled by the vehicle controller; In the power-on state, the electromagnetic brake is released, and the vehicle can drive; in the power-off state, the electromagnetic brake locks the motor shaft, and the vehicle cannot drive. This four-wheeled electric vehicle is safer when in use than the electric vehicle disclosed in the previous patent. At present, this kind of four-wheel electric vehicle has been put into use in large quantities, especially in various scenic spots, but tourists who have used this kind of vehicle report that it is difficult to concentrate on driving the vehicle during the tour, and most of the attention The force may be concentrated on the scenic spot, so when there is an obstacle in front, it may not be noticed immediately, and the equidistant obstacle is not noticed until it is very close or has been hit, and it is difficult to react in time, and the single-pedal vehicle adopts The design requires a certain adaptation process for tourists who use this vehicle for the first time. There is no major problem in normal driving, but when such an emergency occurs, it is difficult to make correct operations in a panic. Therefore, in order to Further improve the safety performance of this four-wheel electric vehicle, the present invention has made further improvement.

Contents of the invention

The technical problem to be solved by the present invention is: for the existing four-wheeled electric vehicle, there is no means of controlling the vehicle from the safety aspect for the obstacles in front of the vehicle, and safety accidents will occur when the driver is inattentive. In order to further improve the safety of the vehicle Safety performance, the present invention provides a kind of safety guarantee method of four-wheel electric vehicle to solve the above-mentioned problem.

The technical scheme that the present invention adopts to solve its technical problem is: a kind of safety assurance method of four-wheel electric vehicle, comprises the following steps:

S1. Detect the position of the pedal in real time, detect the vehicle speed v1 in real time and calculate the real-time acceleration a of the vehicle, and divide the entire stroke of the pedal into a mechanical braking area, a speed change area and an electronic braking area in sequence from large to small.

S2. Control the first ultrasonic sensor to emit a section of ultrasonic waves, and start timing at the same time, the time is t, the first ultrasonic sensor closes the echo detection, and the second ultrasonic sensor enters the echo detection state;

S3, when the time t is equal to the safety time t0, the second ultrasonic sensor has not detected the echo, then stop the timing, control the first ultrasonic sensor to enter the echo detection state, the second ultrasonic sensor turns off the echo detection, and control the second ultrasonic sensor The sensor sends out a section of ultrasonic waves, and starts timing at the same time, the time is t; when the time t is equal to the safety time t0, the first ultrasonic sensor has not detected the echo, then return to step S2;

S4. When the second ultrasonic sensor detects an echo in step S2, or when the first ultrasonic sensor detects an echo in step S3, stop timing, the time t is less than the safety time t0, and calculate the distance between the obstacle and the vehicle body distance s;

S5. Return to step S2 when the distance s is greater than the safety distance s0, and enter step S6 when the distance s is less than or equal to the safety distance s0;

S6. Calculate the safe acceleration a0 according to the distance s and the vehicle speed v1;

When the position of the pedal is in the mechanical braking area, if the real-time acceleration a is greater than or equal to the safe acceleration a0, then the electronic brake will be activated, otherwise it will not be activated;

When the position of the pedal is in the shifting area, start the electronic brake;

When the position of the pedal is in the electronic braking area, start the electronic braking.

Preferably, in step S6, when the position of the pedal is in the speed change zone, the output power of the electronic brake is adjusted according to the safe acceleration a0, so that the acceleration given to the vehicle by the electronic brake is less than the safe acceleration a0.

Preferably, in step S6, when the position of the pedal is in the speed change zone, if the acceleration given to the vehicle by the maximum output power of the electronic brake is still greater than or equal to the safe acceleration a0, an alarm is issued to remind the user to step on the pedal to the mechanical brake zone.

Preferably, in step S6, when the position of the pedal is in the electronic braking zone, if the real-time acceleration a is less than the safe acceleration a0, then the output power of the electronic brake is controlled according to the position of the pedal, otherwise the output power of the electronic brake is adjusted according to the safe acceleration a0.

Preferably, in step S6, when the position of the pedal is in the electronic braking area and the output power of the electronic brake needs to be adjusted according to the safe acceleration a0, if the acceleration given to the vehicle by the maximum output power of the electronic brake is still greater than or equal to the safe acceleration a0, then send An alarm to remind the user to step on the pedal to the mechanical braking zone.

The beneficial effect of the present invention is that the safety assurance method of the four-wheel electric vehicle relies on the ultrasonic sensor to detect the obstacle ahead, and reasonably controls the braking of the vehicle according to the distance between the obstacle and the vehicle, the position of the pedal, the vehicle speed, and the acceleration. The system effectively guarantees the safety of the vehicle and the driver.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is a flow chart of an optimal embodiment of a safety assurance method for a four-wheeled electric vehicle of the present invention.

Detailed ways

Embodiments of the present invention are described in detail below, examples of which are shown in the drawings, wherein the same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary only for explaining the present invention and should not be construed as limiting the present invention.

In describing the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", " Back", "Left", "Right", "Vertical", "Horizontal", "Top", "Bottom", "Inner", "Outer", "Axial", "Radial", "Circumferential", etc. The indicated orientation or positional relationship is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, or in a specific orientation. construction and operation, therefore, should not be construed as limiting the invention.

In addition, the terms "first", "second", etc. are used for descriptive purposes only, and should not be construed as indicating or implying relative importance. In the description of the present invention, it should be noted that unless otherwise specified and limited, the terms "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral Ground connection; it can be mechanical connection or electrical connection; it can be direct connection or indirect connection through an intermediary. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention in specific situations. In addition, in the description of the present invention, unless otherwise specified, "plurality" means two or more.

Any process or method descriptions in flowcharts or otherwise described herein may be understood to represent modules, segments or portions of code comprising one or more executable instructions for implementing specific logical functions or steps of the process , and the scope of preferred embodiments of the invention includes alternative implementations in which functions may be performed out of the order shown or discussed, including substantially concurrently or in reverse order depending on the functions involved, which shall It is understood by those skilled in the art to which the embodiments of the present invention pertain.

As shown in Figure 1, the present invention provides a kind of safety guarantee method of four-wheel electric vehicle, comprises the following steps:

S1. Real-time detection of the position of the pedal. There is a magnet fixed on the pedal, and a Hall sensor is set within the range of the magnetic force line of the magnet. When the position of the pedal changes, the magnetic field generated by the magnet will also change. The vehicle controller communicates with the Hall sensor Connect the Hall sensor and calculate the position of the pedal through the data detected by the Hall sensor, detect the vehicle speed v1 in real time and calculate the real-time acceleration a of the vehicle. The motor of the electric vehicle is a brushless DC motor with its own Hall sensor. The vehicle controller is connected to transmit the detected rotational speed of the motor rotor to the vehicle controller, and the vehicle controller can calculate the vehicle speed, and the real-time acceleration can be calculated according to the vehicle speed and the recorded time; the entire stroke of the pedal is from large to small It is divided into mechanical braking area, shifting area and electronic braking area in turn;

The first ultrasonic sensor and the second ultrasonic sensor are arranged at the head interval of the vehicle, and their transducers are all facing forward; the first ultrasonic sensor and the second ultrasonic sensor are connected with the PIC single-chip microcomputer through the CAN communication bus, and the PIC single-chip microcomputer and the vehicle controller Connection, the PIC single-chip microcomputer acts as the control body of the first ultrasonic sensor and the second ultrasonic sensor, and transmits the collected data to the vehicle controller, and the vehicle controller controls the braking system;

S2. Control the first ultrasonic sensor to emit a section of ultrasonic waves, and start timing at the same time, the time is t, the first ultrasonic sensor closes the echo detection, and the second ultrasonic sensor enters the echo detection state;

S3, when the time t is equal to the safety time t0, the second ultrasonic sensor has not detected the echo, then stop the timing, control the first ultrasonic sensor to enter the echo detection state, the second ultrasonic sensor turns off the echo detection, and control the second ultrasonic sensor The sensor emits a section of ultrasonic waves, and starts timing at the same time, the time is t; when the time t is equal to the safety time t0, the first ultrasonic sensor has not detected the echo, then return to step S2; the two ultrasonic sensors alternately emit ultrasonic waves and detect echoes, Avoid the problem of mutual interference caused by multiple sending and receiving, and improve the detection accuracy;

S4. When the second ultrasonic sensor detects an echo in step S2, or when the first ultrasonic sensor detects an echo in step S3, stop timing. At this time, the time t is less than the safety time t0, and the wave velocity is multiplied by the time t and then divided. Take 2 to get the distance s;

S5. When the distance s is greater than the safety distance s0, return to step S2, and when the distance s is less than or equal to the safety distance s0, enter step S6; the safety distance s0 is a preset value, and when the distance between the vehicle and the obstacle is greater than s0, it means they There is still a long distance between them, and the vehicle is temporarily safe;

S6, calculate safe acceleration a0=-(v1 ² /2s) according to distance s and vehicle speed v1;

When the position of the pedal is in the mechanical braking area, the real-time acceleration a is a negative value. If the real-time acceleration a is greater than or equal to the safe acceleration a0, it means that the current deceleration degree is not enough to stop the vehicle before hitting an obstacle, and then start the electronic brake, otherwise it will not start;

When the position of the pedal is in the shifting area, it means that the vehicle will keep driving until it hits an obstacle, so activate the electronic brake, adjust the output power of the electronic brake according to the safe acceleration a0, so that the acceleration given to the vehicle by the electronic brake is less than the safe acceleration a0; if the electronic brake If the acceleration given to the vehicle by the maximum output power of the brake is still greater than or equal to the safe acceleration a0, an alarm will be issued to remind the user to step on the pedal to the mechanical braking area; if the electronic brake can stop the vehicle before hitting an obstacle, there is no need Remind the user to step on the pedal, which will cause the user to panic even more. For those who are not familiar with the single-pedal operation, it is easy for them to make a wrong operation;

When the position of the pedal is in the electronic braking area, start the electronic brake; because the electronic brake will be activated when the pedal is in the electronic braking area, the electronic brake controls the output power of the electronic brake according to the position of the pedal. At this time, if the real-time acceleration a is less than the safe acceleration a0, Just keep the status quo, but if the real-time acceleration a is greater than or equal to the safe acceleration a0, then adjust the output power of the electronic brake according to the safe acceleration a0; if the acceleration given to the vehicle by the maximum output power of the electronic brake is still greater than or equal to the safe acceleration a0, an alarm will be issued , to remind the user to step on the pedal to the mechanical braking area.

In the description of this specification, descriptions referring to the terms "one embodiment", "some embodiments", "example", "specific examples", or "some examples" mean that specific features described in connection with the embodiment or example , structure, material or characteristic is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

Inspired by the above-mentioned ideal embodiment according to the present invention, through the above-mentioned description content, relevant workers can make various changes and modifications within the scope of not departing from the technical idea of the present invention. The technical scope of the present invention is not limited to the content in the specification, but must be determined according to the scope of the claims.

Claims (5)

1. a kind of method for protecting of four-wheel electric motor car, which comprises the following steps:

The position of S1, real-time detection pedal, real-time detection speed v1 and the real time acceleration a for calculating vehicle, by the whole of pedal Stroke is divided into mechanical brake area, speed-change area and electric brake area from big to small,

S2, the first ultrasonic sensor of control issue one section of ultrasonic wave, start simultaneously at timing, time t, the first supersonic sensing Device closes echo detecting, and the second ultrasonic sensor enters echo detecting state；

S3, when time t be equal to safety time t0 when, echo is still not detected in the second ultrasonic sensor, then stop timing, control First ultrasonic sensor enters echo detecting state, and the second ultrasonic sensor closes echo detecting, controls the second ultrasonic wave Sensor issues one section of ultrasonic wave, starts simultaneously at timing, time t；When time t is equal to safety time t0, the first ultrasonic wave Echo is still not detected in sensor, then return step S2；

S4, in step s 2 when the second ultrasonic sensor detects echo, or the first ultrasonic sensor in step s3 When detecting echo, stop timing, time t is less than safety time t0, calculates the distance between barrier and car body s；

S5, the return step S2 when distance s is greater than safe distance s0, enter step when distance s is less than or equal to safe distance s0 S6；

S6, safe acceleration a0 is calculated according to distance s and speed v1；

When the position of pedal is in mechanical brake area, if real time acceleration a starts electronics more than or equal to safe acceleration a0 It stops, does not otherwise start；

When the position of pedal is in speed-change area, starting electronics is stopped；

When the position of pedal is in electric brake area, starting electronics is stopped.

2. the method for protecting of four-wheel electric motor car as described in claim 1, it is characterised in that: in step s 6, work as pedal Position be in speed-change area, the output power that electronics is stopped is adjusted according to safe acceleration a0, so that electronics is stopped and gives the acceleration of vehicle Degree is less than safe acceleration a0.

3. the method for protecting of four-wheel electric motor car as claimed in claim 2, it is characterised in that: in step s 6, work as pedal Position be in speed-change area, if electronics stop peak power output give vehicle acceleration be still greater than be equal to safety accelerate A0 is spent, then is sounded an alarm, user is reminded to step on pedal to mechanical brake area.

4. the method for protecting of four-wheel electric motor car as described in claim 1, it is characterised in that: in step s 6, work as pedal Position be in electric brake area, if real time acceleration a be less than safe acceleration a0, according to the position control electronics of pedal Otherwise the output power of brake adjusts the output power that electronics is stopped according to safe acceleration a0.

5. the method for protecting of four-wheel electric motor car as claimed in claim 4, it is characterised in that: in step s 6, work as pedal Position be in electric brake area, need according to safe acceleration a0 adjust electronics stop output power when, if electronics stop The acceleration that peak power output gives vehicle is still greater than equal to safe acceleration a0, then sounds an alarm, and reminds user that will step on Plate is stepped on to mechanical brake area.