CN106383351A - Ultrasonic intelligent ranging alarm system, rear end collision prevention method, and overtaking side direction collision prevention method - Google Patents

Abstract

The invention discloses an ultrasonic intelligent ranging alarm system, a rear end collision prevention method, and an overtaking side direction collision prevention method. The system comprises a SCM control module, an ultrasonic ranging module, an alarm module and a display module. The SCM control module is used for counting through an internal timer, recording the time of round-trip propagation between an ultrasonic emission point and an obstacle, and calculating the distance between the obstacle and the ultrasonic emission point; and comparing the distance and a preset alarm threshold in the SCM control module, and sending an alarm signal to the alarm module when the distance is smaller than the alarm threshold. The ultrasonic ranging module is electrically connected to the SCM control module and is used for emitting the pulse signal outputted by the SCM control module, and receiving an ultrasonic echo signal and inputting the ultrasonic echo signal into the SCM control module. The alarm module is electrically connected to the SCM control module and is used for alarming according to the alarm signal emitted by the SCM control module. The display module is electrically connected to the SCM control module and is used for displaying the distance between the ultrasonic emission point and the obstacle.

Description

A kind of ultrasonic intelligent distance measurement alarm system and follower's collision prevention method are laterally prevented with overtaking other vehicles Hit method

Technical field

The technical field the present invention relates to vehicle backing is overtaken other vehicles is and in particular to a kind of ultrasonic intelligent distance measurement alarm system and chasing after Tail avoiding collision and Lateral Collision Avoidance method of overtaking other vehicles.

Background technology

The continuous development of Chinese society economy, people are also increasing to the dependency of this vehicles of automobile, lead to The increasingly increase of vehicle, while being continuously applied to pressure to urban transportation, has also caused the safety problems of very many drivings. Some vapour grazings do not reacted not rapid and led to by driver, be many times also due to driver to from barrier away from Cause from judging inaccurate, if driver can know the presence of barrier in advance and know the distance of barrier, that Driver just can take measures in time, thus being avoided that the generation of accident.Therefore, many security systems are also arisen at the historic moment, The passive safety system of the protection safety such as in order to avoid the active safety system of vehicle accident generation and when having an accident, And active safety system can play, to the generation of motor traffic accidentss, the effect avoiding, so, the research of active safety system is more For important.With the increase of automobile quantity, the quantity in parking lot also sharply increases, and parking vehicle is intensive, and parking people is many, so vapour Car collision also gradually increases.And the anti-collision device for automobile of the present invention is exactly active safety system, by automobile and barrier it Between distance prompting report to the police avoid the wiping between automobile and barrier to touch.The anti-collision device for automobile of application claims design can reduce The motoring pressure of driver and misjudgment, make driver park reversing more safe ready, and the present invention will be to improving traffic peace Entirely play an important role.

The present invention is based on chip microcontroller automobile collision preventing, ultrasonic ranging and sensor is linked together, using monolithic The real-time control data processing function measurement of machine the distance between display automobile and barrier, and utilize honeybee in different distance Ring device different frequency sends alternative sounds and alarm.So driver just can by range finding display not even with sound Lai Directly judge the distance between automobile and barrier.The design of the present invention is simple, small scale, peripheral circuit are simple, debugging is convenient, With low cost, device replacing is easy, motility is high, and can fully meet needs when driver parks, and can release completely Misgivings in reversing process for the driver and puzzlement, improve the safety parked.

Anti-collision device for automobile this automotive safety auxiliary device can greatly reduce driver's misgivings when reversing Error with judgement of adjusting the distance is such that it is able to avoid the generation of the safety problem of reversing, so device is for raising traffic safety To play an important role.So, the SCM Based anti-collision device for automobile of the present invention will have great realistic meaning and Market.

Content of the invention

In order to overcome deficiency of the prior art, the present invention provides a kind of ultrasonic intelligent distance measurement alarm system, has knot The feature that structure is simple, measurement is accurate, with low cost.

Present invention also offers a kind of follower's collision prevention method.

Invention additionally provides a kind of Lateral Collision Avoidance method of overtaking other vehicles.

In order to reach foregoing invention purpose, solve the technical scheme that its technical problem adopted as follows：

The invention discloses a kind of ultrasonic intelligent distance measurement alarm system, including single chip control module, ultrasonic ranging Module, alarm module and display module, wherein：

Described single chip control module, in order to：

Counted by internal intervalometer, record ultrasonic emitting point roundtrip propagation to barrier used by when Between, and calculate the distance between barrier and ultrasonic emitting point；

By the distance between barrier and ultrasonic emitting point warning level with described single chip control module internal preset Value is compared, and when the distance between barrier and ultrasonic emitting point are less than alarm threshold value, sends an alarm signal to institute State alarm module；

Described ultrasonic distance measuring module is electrically connected with described single chip control module, in order to：

By described single chip control module output pulse signal launch, and receive ultrasonic echo signal input to Described single chip control module；

Described alarm module is electrically connected with described single chip control module, in order to be sent out according to described single chip control module The alarm signal sent is reported to the police；

Described display module is electrically connected with described single chip control module, in order to show ultrasonic emitting point and barrier The distance between.

Further, described ultrasonic distance measuring module includes ultrasonic emitting circuit and ultrasound wave receiving circuit, wherein：

Described ultrasonic emitting circuit includes ultrasonic amplifier and ultrasonic emitting probe, and described ultrasonic amplifier will The pulse signal of described single chip control module output is converted into mechanical wave through described ultrasonic emitting probe after being amplified and sends out It is shot out, described ultrasonic amplifier adopts 74LS04 amplifying circuit；

Described ultrasound wave receiving circuit includes ultrasound wave receiving transducer, integrated circuit CX20106A chip circuit, described super Acoustic receiver probe receives the ultrasonic signal that the mechanical wave of described ultrasonic emitting probe transmitting reflects, institute through barrier State CX20106A chip circuit in order to be amplified to the ultrasonic signal receiving, amplitude limit, bandpass filtering, peak detection, whole Shape, compare；

Described ultrasonic emitting probe and ultrasound wave receiving transducer are located in same level parallel lines, and between the two Distance is between 5cm-8cm.

Preferably, described ultrasonic emitting probe, ultrasound wave receiving transducer, integrated circuit CX20106A chip circuit and 74LS04 amplifying circuit is integrated into a HR-SR04 ultrasound wave integration module.

Further, also include keyboard input module, described keyboard input module is connected with described single chip control module, In order to set alarm distance.

Preferably, described display module is 4 common cathode charactrons.

Preferably, described single chip control module is STC89C52 type single-chip microcomputer.

Preferably, described alarm module is buzzer.

In addition the present invention discloses a kind of follower's collision prevention method, using the ultrasonic intelligent range finding described in above-mentioned any one Warning system, its step includes：

Step 1：Test data in ultrasonic distance measuring module is received by single chip control module, and it is static to calculate front truck Or front is when being barrier, from danger warning distance and the reminding alarm distance of car and front truck；

Step 2：When calculating front truck is at the uniform velocity exercised, from danger warning distance and the reminding alarm distance of car and front truck；

Step 3：When calculating front truck deceleration enforcement, from danger warning distance and the reminding alarm distance of car and front truck.

Further, in step 1, front truck pass by apart from X₂For 0, alarm distance d be from car pass by apart from X₁Plus peace Full spacing d₀Sum, specifically includes following steps：

Step 11：Calculate danger warning distance；

$X_1=v_1(t_a+\frac{t_s}{2})+\frac{v_1^2}{2a_1}$

Therefore,

Wherein, X₁Represent the distance passed by from car, unit is m；v₁Represent from vehicle speed, unit is m/s；t_aRepresent braking The time coordinated by device, and unit is s；t_sRepresent braking deceleration rise time, unit is s；a₁Represent from car braking deceleration, unit For m/s²；d_bRepresent danger warning distance, unit is m；d₀Represent safe spacing, unit is m；

Step 12：Calculate reminding alarm distance；

$X_1=v_1(t_a+t_r+\frac{t_s}{2})+\frac{v_1^2}{2a_1}$

Therefore,

Wherein, t_rRepresent time of driver's reaction, unit is s；d_wRepresent reminding alarm distance, unit is m.

Further, in step 2, alarm distance d plus front truck pass by apart from X₂Sum be equal to from car pass by apart from X₁ Plus safe spacing d₀Sum, specifically includes following steps：

Step 21：Calculate danger warning distance；

X₁=s₁+s₂+s₃,

Wherein, X₁Represent the distance passed by from car, unit is s；s₁、s₂、s₃It is in reaction time of braking device t from car_a, braking Deceleration rise time t_s, time of driver's reaction t_rThe distance running in three time periods,

s₁=v₁t_a

Wherein, v₁Represent from vehicle speed, unit is m/s；

In braking deceleration rise time t_sEnd, from end speed v of car '₁For

$v_1^{,}=v_1-\frac{a_1}{2t_s}{t}^2$

Make t=t_s, then：

$v_1^{,}=v_1-\frac{a_1{t}_s}{2}$

Wherein, a₁Represent from car braking deceleration, unit is m/s²；

Being located at braking deceleration on dry pavement is 6m/s², t_sFor 0.2s, then

$v_1-v_1^{,}=\frac{a_1{t}_s}{2}$

Substitute into parameter, can calculate and come from car in t_sEnd speed will reduce 0.6m/s, and currently rear speed difference is less than 0.6m/s When, from car braking deceleration without reach maximum will be also lower than front vehicle speed from vehicle speed, if now from car braking deceleration The rise time of degree is t ',

$s_2={\∫}_0^t(v_1-\frac{a_1}{2t_s}{t}^2)dt=v_1{t}^{,}-\frac{a_1{t}^{,3}}{6t_s}$

$t^{,}=\sqrt{\frac{2v_{rel}{t}_s}{a_1}}$

$X_1=v_1{t}_a+v_1{t}^{,}-\frac{a_1{t}^{,3}}{6t_s}$

X₂=v₂t_a+v₂t’

Therefore,

Make v_rel=v₁-v₂

$d_b=v_{rel}(t_a+t^{,})-\frac{a_1{t}^{,3}}{6t_s}+d_0$

Wherein, v_relRepresent relative velocity, unit is m/s；X₂Represent the distance that front truck is passed by, unit is m；d_bRepresent danger Alarm distance, unit is m；v₂Vehicle speed before representative, unit is m/s；d₀Represent safe spacing, unit is m；

After currently, speed is when differing by more than equal to 0.6m/s, will reach maximum existing from car braking deceleration and hold Continuous braking time, if now from the car continuous braking time be t '_v,

$t_v^{,}=\frac{2v_{rel}-a_1{t}_s}{2a_1}$

$X_1=v_1(t_a+\frac{t_s}{2})+\frac{(2v_1{v}_{rel}-v_{rel}^2)}{2a_1}$

$X_2=v_2(t_a+t_s+t_v^{,})=v_2(t_a+\frac{t_s}{2}+\frac{v_{rel}}{a_1})$

Therefore, d_b=X₁-X₂+d₀

$d_b=v_{rel}(t_a+\frac{t_s}{2})+\frac{v_{rel}^2}{2a_1}+d_0$

Step 22：Calculate reminding alarm distance；

When after currently, speed difference is less than 0.6m/s,

$X_1=v_1(t_r+t_a)+v_1{t}^{,}-\frac{a_1{t}^{,3}}{6t_s}$

X₂=v₂(t_r+t_a)+v₂t’

$d_w=v_{rel}(t_a+t_r+t^{,})-\frac{a_1{t}^{,3}}{6t_s}+d_0$

When after currently, speed differs by more than equal to 0.6m/s,

$X_1=v_1(t_r+t_a+\frac{t_s}{2})|\frac{(2v_1{v}_{rel}-v_{rel}^2)}{2a_1}$

$X_2=v_2(t_r+t_a+t_s+t_v^{,})=v_2(t_r+t_a+\frac{t_s}{2}+\frac{v_{rel}}{a_1})$

$d_w=v_{rel}(t_r+t_a+\frac{t_s}{2})+\frac{v_{rel}^2}{2a_1}+d_0$

Wherein, d_wRepresent reminding alarm distance, unit is m.

Further, in step 3, following steps are specifically included：

Step 31：Calculate danger warning distance；

$X_1=v_1(t_a+\frac{t_s}{2})+\frac{v_1^2}{2a_1}$

$X_2=\frac{v_2{t}_s}{2}+\frac{v_2^2}{2a_2}$

$d_b+\frac{v_2{t}_s}{2}+\frac{v_2^2}{2a_2}=v_1(t_a+\frac{t_s}{2})+\frac{v_1^2}{2a_1}+d_0$

Make a₁=a₂=a, then

$d_b=v_1{t}_a+v_{rel}\frac{t_s}{2}+\frac{v_{rel}(2v_1-v_{rel})}{2a}+d_0$

Wherein, X₁Represent the distance passed by from car, unit is m；X₂Represent the distance that front truck is passed by, unit is m；v₁Represent From vehicle speed, unit is m/s；v₂Vehicle speed before representative, unit is m/s；v_relRepresent relative velocity, unit is m/s；t_aRepresent system The time coordinated by dynamic device, and unit is s；t_sRepresent braking deceleration rise time, unit is s；a₁Represent from car braking deceleration, single Position is m/s²；a₂Represent front truck braking deceleration, unit is m/s²；d₀Represent safe spacing, unit is m；d_bRepresent danger warning Distance, unit is m；

Step 32：Calculate reminding alarm distance；

$X_1=v_1(t_r+t_a+\frac{t_s}{2})+\frac{v_1^2}{2a_1}$

$X_2=\frac{v_2{t}_s}{2}+\frac{v_2^2}{2a_2}$

$d_w=v_1(t_r+t_a)+v_{rel}\frac{t_s}{2}+\frac{v_{rel}(2v_1-v_{rel})}{2a}+d_0$

Wherein, t_rRepresent time of driver's reaction, unit is s；d_wRepresent reminding alarm distance, unit is m.

The Lateral Collision Avoidance method the invention also discloses one kind is overtaken other vehicles, is surveyed using the ultrasonic intelligent described in above-mentioned any one Away from warning system, its step includes：

Step A：Test data in ultrasonic distance measuring module is received by single chip control module, and calculates and overtake other vehicles from car Minimum corner and fore-and-aft distance；

Step B：Calculate and overtake other vehicles hard-over and fore-and-aft distance from car；

Step C：Minimum safe distance when calculating is overtaken other vehicles.

Further, step A specifically includes following calculation procedure：

$\frac{z}{\frac{y}{2}}=\frac{R}{2z},z=\frac{1}{2}\sqrt{yR},sin\frac{\mathrm{\α}}{2}=\frac{z}{R}=\frac{\frac{1}{2}\sqrt{yR}}{R}$

Wherein,

Order

$Lx=\frac{y}{tan\left(\frac{\mathrm{\α}}{2}\right)}$

Wherein, v₁Represent from vehicle speed, unit is m/s；a_cRepresent from car lateral acceleration, unit is m/s²；R represents back Turn radius, unit is m；Z represents lateral overtaking process and enters the 1/2 of displacement from garage, and unit is m；W₁Represent from vehicle-width, unit For m；W₂Vehicle-width before representative, unit is m；Y represents the sidesway distance from car centrage, and unit is m；α represents minimum corner, single Position for °；c_rRepresent from the right side of car to safe spacing, unit is m；Lx represents fore-and-aft distance during minimum corner from car and front truck, Unit is m.

Further, step B specifically includes following calculation procedure：

$\frac{z}{\frac{y}{2}}=\frac{R}{2z},z=\frac{1}{2}\sqrt{yR},sin\frac{\mathrm{\β}}{2}=\frac{z}{R}=\frac{\frac{1}{2}\sqrt{yR}}{R}$

Wherein,

Order

$Ld=\frac{y}{tan\left(\frac{\mathrm{\β}}{2}\right)}$

Wherein, v₁Represent from vehicle speed, unit is m/s；a_cRepresent from car lateral acceleration, unit is m/s²；R represents back Turn radius, unit is m；Z represents lateral overtaking process and enters the 1/2 of displacement from garage, and unit is m；W₁Represent from vehicle-width, unit For m；L represents lane width, and unit is m；Y represents the sidesway distance from car centrage, and unit is m；β represents hard-over, single Position for °；c_lRepresent from the left of car to safe spacing, unit is m；Ld represents fore-and-aft distance during hard-over from car and front truck, Unit is m.

Further, step C specifically includes following calculation procedure：

Assume that vehicle starts to overtake other vehicles in the t=0 moment, in 0～t_cIn time period, application transverse acceleration completes overtaking process, With the upper right corner of automobile M as reference point, lateral distance is H, then at H/2, the lateral velocity of automobile reaches maximum, Assume that overtaking process is steady, then, v_c-yMeet sine wave characteristics, then the transverse acceleration of automobile meets a_c-yCosine baud Property, if：

a_c-y(t)=A*sin (ω t+ pi/2) (0≤t≤t_c)

Wherein：A is undetermined coefficient, ω=2 π/t_c

Thus having：

${\∫}_0^{t_c}{\∫}_0^{t}Asin(\mathrm{\ω}t-\mathrm{\π}/2)d\mathrm{\τ}dt=H$

Obtain：So：

$\begin{array}{cc}{a}_{c-y}\left(t\right)=\frac{2\mathrm{\π}H}{t_c^2}sin(\frac{2\mathrm{\π}}{t_c}t-\frac{\mathrm{\π}}{2})& (0\≤t\≤t_c)\end{array}$

On the other hand, during automobile overtaking, transverse acceleration comes from the cross stream component of direct of travel acceleration, if t Moment automobile direct of travel is θ (t) in the longitudinal angle of road, has：

$tan\left(\mathrm{\θ}\right(t\left)\right)=\frac{\∂y_c\left(t\right)}{\∂x_M\left(t\right)}=\frac{\∂y_c\left(t\right)/\∂t}{\∂x_M\left(t\right)/\∂t}=\frac{V_{c-y}\left(t\right)}{V_{c-x}\left(t\right)}$

Wherein：x_M(t)、V_c-xT () is respectively length travel and the longitudinal velocity that t automobile prolongs road direction；a_c-yGeneration Table represents from car lateral distance, x from car transverse acceleration, H_MRepresent from car length travel, tc represents passing time, Vc-y Represent from car lateral velocity, Vc-x represents from car longitudinal velocity, y_cRepresent lateral displacement.

The present invention is due to using above technical scheme, being allowed to compared with prior art, have the following advantages that and actively imitate Really：

1st, due to present invention employs STC89C52 type single-chip microcomputer, data acquiring frequency and calculating frequency are higher, therefore, survey Amount speed is fast, and certainty of measurement is high, and good stability can send alarm under dangerous situation in time and dissolve crisis；

2nd, the present invention has frequency of vibration height using ultrasound wave, wavelength is short, diffraction phenomenon is little and good directionality can also The advantages of for reflected ray direction propagation, and the energy expenditure of ultrasonic sensor is slowly conducive to finding range.In, distance survey During amount, the precision of ultrasonic sensor and directivity will be significantly better than infrared ray sensor；

3rd, present configuration is simple, with low cost, and certainty of measurement is high；

4th, the present invention mainly uses the Intelligent ultrasonic distance measuring sensor with single-chip microcomputer as control core and buzzer Warning system, this safe assisting system for automobiles is cheaply durable, and has reached the growth requirement of automobile electronic system networking.

Brief description

In order to be illustrated more clearly that the technical scheme of the embodiment of the present invention, below will be to required use in embodiment description Accompanying drawing be briefly described.It is clear that drawings in the following description are only some embodiments of the present invention, for ability For field technique personnel, on the premise of not paying creative work, other accompanying drawings can also be obtained according to these accompanying drawings.Attached In figure：

Fig. 1 is a kind of system block diagram of present invention ultrasonic intelligent distance measurement alarm system；

Fig. 2 is the circuit diagram of ultrasonic emitting circuit in the present invention；

Fig. 3 is the circuit diagram of ultrasound wave receiving circuit in the present invention；

Fig. 4 is the pin function figure of single-chip microcomputer in the present invention；

Fig. 5 is that display module of the present invention connects circuit diagram；

Fig. 6 is alarm module circuitry figure of the present invention；

Fig. 7 is keyboard input module circuit diagram of the present invention；

Fig. 8 is from car and front truck relative position schematic diagram in the present invention；

Fig. 9 is minimum corner schematic diagram of overtaking other vehicles in the present invention；

Figure 10 is hard-over schematic diagram of overtaking other vehicles in the present invention；

Figure 11 is overtaking process dynamic analyses figure in the present invention；

The cut-in situation that Figure 12 is common is position view；

Figure 13 is the crash analysises schematic diagram of F and M in the present invention；

Figure 14 is overtaking process radius of curvature schematic diagram in the present invention.

【Primary symbols explanation】

1- single chip control module；

2- alarm module；

3- display module；

4- ultrasonic amplifier；

5- ultrasonic emitting is popped one's head in；

6- ultrasound wave receiving transducer；

7- IC chip.

Specific embodiment

Below with reference to the accompanying drawing of the present invention, clear, complete description is carried out to the technical scheme in the embodiment of the present invention With discussion it is clear that a part of example of the only present invention as described herein, it is not whole examples, based on the present invention In embodiment, the every other enforcement that those of ordinary skill in the art are obtained on the premise of not making creative work Example, broadly falls into protection scope of the present invention.

Embodiment one

As shown in figure 1, the invention discloses a kind of ultrasonic intelligent distance measurement alarm system, including single chip control module 1, Ultrasonic distance measuring module, alarm module 2 and display module 3, wherein：

Described single chip control module 1, in order to：

Counted by internal intervalometer, record ultrasonic emitting point roundtrip propagation to barrier used by when Between, and calculate the distance between barrier and ultrasonic emitting point；

By the distance between barrier and ultrasonic emitting point warning level with described single chip control module 1 internal preset Value is compared, and when the distance between barrier and ultrasonic emitting point are less than alarm threshold value, sends an alarm signal to institute State alarm module 2；

Described ultrasonic distance measuring module is electrically connected with described single chip control module 1, in order to：

The pulse signal that described single chip control module 1 is exported is launched, and receives ultrasonic echo signal input To described single chip control module 1；

Described alarm module 2 is electrically connected with described single chip control module 1, in order to according to described single chip control module The alarm signal of 1 transmission is reported to the police；

Described display module 3 is electrically connected with described single chip control module 1, in order to show ultrasonic emitting point and obstacle The distance between thing.

Further, described ultrasonic distance measuring module includes ultrasonic emitting circuit and ultrasound wave receiving circuit, wherein：

Described ultrasonic emitting circuit includes ultrasonic amplifier 4 and ultrasonic emitting probe 5, described ultrasonic amplifier 4 pulse signals exporting described single chip control module 1 are converted into machinery through described ultrasonic emitting probe 5 after being amplified Ripple is launched, and described ultrasonic amplifier 4 adopts 74LS04 amplifying circuit, in the present embodiment, described ultrasonic emitting circuit As shown in Fig. 2 during work, the pulse of 40kHz is produced from P0.1 mouth to the radiating circuit portion of ultrasound wave from single chip control module 1 Distribute signal, then after the amplification of 74LS04 amplifying circuit, drive ultrasonic emitting probe 5 that ultrasonic emitting is gone out；

Described ultrasound wave receiving circuit includes ultrasound wave receiving transducer 6, integrated circuit CX20106A chip circuit 7, described The mechanical wave that ultrasound wave receiving transducer 6 receives the transmitting of described ultrasonic emitting probe 5 is believed through the ultrasound wave that barrier reflects Number, described CX20106A chip circuit is in order to be amplified to the ultrasonic signal receiving, the inspection of amplitude limit, bandpass filtering, peak value Ripple, shaping, compare, in the present embodiment, the preamplifier of CX20106A chip has the function of automatic growth control, works as measurement Distance closer when, amplifier will not transship；And when measurement distance is distant, ultrasonic signal is faint, preamplifier Just there is larger gain amplifier effect.The frequency of 5 feet band filter to it in outer meeting resistance of CX20106A chip is carried out Adjust, and without external others inductance again, the interference to chip circuit for the externally-applied magnetic field can be avoided well, and it Reliability is also that comparison is high.CX20106A chip circuit inherently has very high jamproof ability, and sensitivity Relatively higher, thus it is possible to meet the requirement of the design.Ultrasound wave receiving circuit is as shown in Figure 3；

In this enforcement, will be separately positioned to ultrasonic emitting probe 5 and ultrasound wave receiving transducer 6, transmitting-receiving so will not be made to believe Number aliasing, so as to avoid interference, can be very good the reliability of raising system.

Because the transmitting of ultrasound wave and reception are separately sends and receive, so ultrasonic emitting probe 5 and ultrasound wave Receiving transducer 6 so just must can be accurately received the echo of reflection on same horizontal line straight line.And due to measurement away from From the errors caused by different and transmitting angles of flare and ultrasonic signal propagate in atmosphere during ultrasonic attenuation Problem, ultrasonic emitting pop one's head in the distance between 5 and ultrasound wave receiving transducer 6 can not ether remote, but also ultrasound wave to be avoided The interference that transmitting probe 5 produces in receipt signal to ultrasound wave receiving transducer 6, so the two can not lean on too near again.By two It is the most suitable that the distance between probe is scheduled on 5cm～8cm, in the present embodiment, HC-SR04 ultrasound wave integration module used super The distance between sonic probe is about in 6cm.

Preferably, described single chip control module 1 is STC89C52 type single-chip microcomputer, is the high property being produced by macrocrystalline company Energy, 8 single-chip microcomputers of CMOS of low-power consumption.STC89C52 single-chip microcomputer has following performance characteristics：In the flash memory piece of 4k byte Program storage, the data storage of 128 bytes, 32 outside inputs and delivery outlet, 2 full duplex serial communication ports, guard the gate Canis familiaris L. circuit, 5 interrupt sources, 2 16 programmer timing counters, concussion and clock circuit and full static work by low in piece The idle and power-down mode of power consumption.The pin function figure of single-chip microcomputer is as shown in Figure 2.

Preferably, described ultrasonic emitting probe 5, ultrasound wave receiving transducer 6, integrated circuit CX20106A chip circuit 7 It is integrated into a HR-SR04 ultrasound wave integration module with 74LS04 amplifying circuit.In the present embodiment, select HC-SR04 ultrasonic Ripple integration module, the maximum detectable range of this ultrasonic wave module is 5m, and precision can reach 0.3cm, and blind area is 2cm, Er Qiefa Penetrate angle of flare and be not more than 15 °, be more beneficial for the accuracy found range.And, the operating frequency range of this module be 39kHz～ 41kHz about, it is entirely capable of working in 40kHz operating frequency.

The running voltage of HR-SR04 ultrasound wave integration module is 5V, and the static working current of this module is less than 2mA , operation can be more stable.And, the angle of its sensing is not more than 15 °, it is possible to reduce significant portion may be deposited Angle interference problem.The finding range of this module is 2cm～5m, can substantially meet range finding and require, and its precision is permissible Reach 0.3cm, blind area is only 2cm, can disclosure satisfy that the range finding of the design requires completely, and it is also more stable to find range. HR-SR04 ultrasound wave integration module uses I/O triggering range finding, at least high level signal of 10us.In addition, this module can With the automatic square-wave pulse sending 8 40kHz, and automatic detection signal whether can be had to return, if signal has been detected returned Hui Ze exports high level by I/O mouth, and persistent period of high level is exactly ultrasound wave returns the time used from being transmitted into, then, Measured distance=(high level time × velocity of sound)/2.

For preventing transmission signal to the impact reclaiming signal, the measure the cycle of this ultrasound wave integration module is preferably scheduled on 60ms More than, so measure the cycle is scheduled on 80ms by the design.

Preferably, described display module 3 is 4 common cathode charactrons, and common cathode is exactly the light-emitting diodes inside charactron It is common cathode that the negative electrode of pipe is connected together as common pin, and when using, this pin is connected to power cathode.In the present embodiment, The display of single-chip microcomputer logarithmic code pipe can be divided into static state display and Dynamic Announce, and static state display stably can show numerical value, but More cumbersome when building circuit, and Dynamic Announce be charactron in turn show recycling human eye " persistence of vision " characteristic, this What sample was found out is exactly numerical value different in display.The Dynamic Announce of charactron is practical, and circuit builds simply, so the design Method using dynamic scan shows measurement distance, as long as can be realized as when the speed showing in turn is sufficiently fast measuring number The display of value.Display module 3 carries out dynamic scan from 4 common cathode charactrons, and this scan mode can be fully achieved display will Ask.It is as shown in Figure 5 that display module connects circuit diagram.

Preferably, described alarm module 2 is buzzer, and alarm module circuitry figure is as shown in Figure 6.

Further, also include keyboard input module, described keyboard input module is with described single chip control module 1 even Connect, in order to set alarm distance.Keyboard input module circuit diagram is as shown in Figure 7.

Embodiment two

In addition the present invention discloses a kind of follower's collision prevention method, using the ultrasonic intelligent range finding report described in embodiment one Alarm system, its step includes：

Step 1：Test data in ultrasonic distance measuring module is received by single chip control module, and it is static to calculate front truck Or front is when being barrier, from danger warning distance and the reminding alarm distance of car and front truck；

Step 2：When calculating front truck is at the uniform velocity exercised, from danger warning distance and the reminding alarm distance of car and front truck；

Step 3：When calculating front truck deceleration enforcement, from danger warning distance and the reminding alarm distance of car and front truck.

Further, as shown in figure 8, in step 1, front truck pass by apart from X₂For 0, alarm distance d passes by from car Apart from X₁Plus safe spacing d₀Sum, specifically includes following steps：

Step 11：Calculate danger warning distance；

$X_1=v_1(t_a+\frac{t_s}{2})+\frac{v_1^2}{2a_1}$

Therefore,

Wherein, X₁Represent the distance passed by from car, unit is m；v₁Represent from vehicle speed, unit is m/s；t_aRepresent braking The time coordinated by device, and unit is s；t_sRepresent braking deceleration rise time, unit is s；a₁Represent from car braking deceleration, unit For m/s²；d_bRepresent danger warning distance, unit is m；d₀Represent safe spacing, unit is m；

Step 12：Calculate reminding alarm distance；

$X_1=v_1(t_a+t_r+\frac{t_s}{2})+\frac{v_1^2}{2a_1}$

Therefore,

Wherein, t_rRepresent time of driver's reaction, unit is s；d_wRepresent reminding alarm distance, unit is m.

Further, in step 2, alarm distance d plus front truck pass by apart from X₂Sum be equal to from car pass by apart from X₁ Plus safe spacing d₀Sum, specifically includes following steps：

Step 21：Calculate danger warning distance；

X₁=s₁+s₂+s₃,

Wherein, X₁Represent the distance passed by from car, unit is s；s₁、s₂、s₃It is in reaction time of braking device t from car_a, braking Deceleration rise time t_s, time of driver's reaction t_rThe distance running in three time periods,

s₁=v₁t_a

Wherein, v₁Represent from vehicle speed, unit is m/s；

In braking deceleration rise time t_sEnd, from end speed v of car₁' be

$v_1^{,}=v_1-\frac{a_1}{2t_s}{t}^2$

Make t=t_s, then：

$v_1^{,}=v_1-\frac{a_1{t}_s}{2}$

Wherein, a₁Represent from car braking deceleration, unit is m/s²；

Being located at braking deceleration on dry pavement is 6m/s², t_sFor 0.2s, then

$v_1-v_1^{,}=\frac{a_1{t}_s}{2}$

Substitute into parameter, can calculate and come from car in t_sEnd speed will reduce 0.6m/s, and currently rear speed difference is less than 0.6m/s When, from car braking deceleration without reach maximum will be also lower than front vehicle speed from vehicle speed, if now from car braking deceleration The rise time of degree is t ',

$s_2={\∫}_0^t(v_1-\frac{a_1}{2t_s}{t}^2)dt=v_1{t}^{,}-\frac{a_1{t}^{,3}}{6t_s}$

$t^{,}=\sqrt{\frac{2v_{rel}{t}_s}{a_1}}$

$X_1=v_1{t}_a+v_1{t}^{,}-\frac{a_1{t}^{,3}}{6t_s}$

X₂=v₂t_a+v₂t’

Therefore,

Make v_rel=v₁-v₂

$d_b=v_{rel}(t_a+t^{,})-\frac{a_1{t}^{,3}}{6t_s}+d_0$

Wherein, v_relRepresent relative velocity, unit is m/s；X₂Represent the distance that front truck is passed by, unit is m；d_bRepresent danger Alarm distance, unit is m；v₂Vehicle speed before representative, unit is m/s；d₀Represent safe spacing, unit is m；

After currently, speed is when differing by more than equal to 0.6m/s, will reach maximum existing from car braking deceleration and hold Continuous braking time, if now from the car continuous braking time be t '_v,

$t_v^{,}=\frac{2v_{rel}-a_1{t}_s}{2a_1}$

$X_1=v_1(t_a+\frac{t_s}{2})+\frac{(2v_1{v}_{rel}-v_{rel}^2)}{2a_1}$

$X_2=v_2(t_a+t_s+t_v^{,})=v_2(t_a+\frac{t_s}{2}+\frac{v_{rel}}{a_1})$

Therefore, d_b=X₁-X₂+d₀

$d_b=v_{rel}(t_a+\frac{t_s}{2})+\frac{v_{rel}^2}{2a_1}+d_0$

Step 22：Calculate reminding alarm distance；

When after currently, speed difference is less than 0.6m/s,

$X_1=v_1(t_r+t_a)+v_1{t}^{,}-\frac{a_1{t}^{,3}}{6t_s}$

X₂=v₂(t_r+t_a)+v₂t’

$d_w=v_{rel}(t_a+t_r+t^{,})-\frac{a_1{t}^{,3}}{6t_s}+d_0$

When after currently, speed differs by more than equal to 0.6m/s,

$X_1=v_1(t_r+t_a+\frac{t_s}{2})|\frac{(2v_1{v}_{rel}-v_{rel}^2)}{2a_1}$

$X_2=v_2(t_r+t_a+t_s+t_v^{,})=v_2(t_r+t_a+\frac{t_s}{2}+\frac{v_{rel}}{a_1})$

$d_w=v_{rel}(t_r+t_a+\frac{t_s}{2})+\frac{v_{rel}^2}{2a_1}+d_0$

Wherein, d_wRepresent reminding alarm distance, unit is m.

Further, in step 3, following steps are specifically included：

Step 31：Calculate danger warning distance；

$X_1=v_1(t_a+\frac{t_s}{2})+\frac{v_1^2}{2a_1}$

$X_2=\frac{v_2{t}_s}{2}+\frac{v_2^2}{2a_2}$

$d_b+\frac{v_2{t}_s}{2}+\frac{v_2^2}{2a_2}=v_1(t_a+\frac{t_s}{2})+\frac{v_1^2}{2a_1}+d_0$

Make a₁=a₂=a, then

$d_b=v_1{t}_a+v_{rel}\frac{t_s}{2}+\frac{v_{rel}(2v_1-v_{rel})}{2a}+d_0$

Wherein, X₁Represent the distance passed by from car, unit is m；X₂Represent the distance that front truck is passed by, unit is m；v₁Represent From vehicle speed, unit is m/s；v₂Vehicle speed before representative, unit is m/s；v_relRepresent relative velocity, unit is m/s；t_aRepresent system The time coordinated by dynamic device, and unit is s；t_sRepresent braking deceleration rise time, unit is s；a₁Represent from car braking deceleration, single Position is m/s²；a₂Represent front truck braking deceleration, unit is m/s²；d₀Represent safe spacing, unit is m；d_bRepresent danger warning Distance, unit is m；

Step 32：Calculate reminding alarm distance；

$X_1=v_1(t_r+t_a+\frac{t_s}{2})+\frac{v_1^2}{2a_1}$

$X_2=\frac{v_2{t}_s}{2}+\frac{v_2^2}{2a_2}$

$d_w=v_1(t_r+t_a)+v_{rel}\frac{t_s}{2}+\frac{v_{rel}(2v_1-v_{rel})}{2a}+d_0$

Wherein, t_rRepresent time of driver's reaction, unit is s；d_wRepresent reminding alarm distance, unit is m.

Embodiment three

The Lateral Collision Avoidance method the invention also discloses one kind is overtaken other vehicles, using the ultrasonic intelligent range finding described in embodiment one Warning system, its step includes：

Step A：Test data in ultrasonic distance measuring module is received by single chip control module, and calculates and overtake other vehicles from car Minimum corner and fore-and-aft distance；

Step B：Calculate and overtake other vehicles hard-over and fore-and-aft distance from car；

Step C：Minimum safe distance when calculating is overtaken other vehicles.

Further, as shown in figure 9, step A specifically includes following calculation procedure：

$\frac{z}{\frac{y}{2}}=\frac{R}{2z},z=\frac{1}{2}\sqrt{yR},sin\frac{\mathrm{\α}}{2}=\frac{z}{R}=\frac{\frac{1}{2}\sqrt{yR}}{R}$

Wherein,

Order

$Lx=\frac{y}{tan\left(\frac{\mathrm{\α}}{2}\right)}$

Wherein, v₁Represent from vehicle speed, unit is m/s；a_cRepresent from car lateral acceleration, unit is m/s²；R represents back Turn radius, unit is m；Z represents lateral overtaking process and enters the 1/2 of displacement from garage, and unit is m；W₁Represent from vehicle-width, unit For m；W₂Vehicle-width before representative, unit is m；Y represents the sidesway distance from car centrage, and unit is m；α represents minimum corner, single Position for °；c_rRepresent from the right side of car to safe spacing, unit is m；Lx represents fore-and-aft distance during minimum corner from car and front truck, Unit is m.

Further, as shown in Figure 10, step B specifically includes following calculation procedure：

$\frac{z}{\frac{y}{2}}=\frac{R}{2z},z=\frac{1}{2}\sqrt{yR},sin\frac{\mathrm{\β}}{2}=\frac{z}{R}=\frac{\frac{1}{2}\sqrt{yR}}{R}$

Wherein,

Order

$Ld=\frac{y}{tan\left(\frac{\mathrm{\β}}{2}\right)}$

Wherein, v₁Represent from vehicle speed, unit is m/s；a_cRepresent from car lateral acceleration, unit is m/s²；R represents back Turn radius, unit is m；Z represents lateral overtaking process and enters the 1/2 of displacement from garage, and unit is m；W₁Represent from vehicle-width, unit For m；L represents lane width, and unit is m；Y represents the sidesway distance from car centrage, and unit is m；β represents hard-over, single Position for °；c_lRepresent from the left of car to safe spacing, unit is m；Ld represents fore-and-aft distance during hard-over from car and front truck, Unit is m.

Further, as shown in figure 11, step C specifically includes following calculation procedure：

Assume that vehicle starts to overtake other vehicles in the t=0 moment, in 0～t_cIn time period, application transverse acceleration completes overtaking process, With the upper right corner of automobile M as reference point, lateral distance is H, then at H/2, the lateral velocity of automobile reaches maximum, Assume that overtaking process is steady, then, v_c-yMeet sine wave characteristics, then the transverse acceleration of automobile meets a_c-yCosine baud Property, if：

a_c-y(t)=A*sin (ω t+ pi/2) (0≤t≤t_c)

Wherein：A is undetermined coefficient, ω=2 π/t_c

Thus having：

${\∫}_0^{t_c}{\∫}_0^{t}Asin(\mathrm{\ω}t-\mathrm{\π}\mathrm{/2})d\mathrm{\τ}dt=H$

Obtain：So：

$\begin{array}{cc}{a}_{c-y}\left(t\right)=\frac{2\mathrm{\π}H}{t_c^2}sin(\frac{2\mathrm{\π}}{t_c}t-\frac{\mathrm{\π}}{2})& (0\≤t\≤t_c)\end{array}$

On the other hand, during automobile overtaking, transverse acceleration comes from the cross stream component of direct of travel acceleration, if t Moment automobile direct of travel is θ (t) in the longitudinal angle of road, has：

$tan\left(\mathrm{\θ}\right(t\left)\right)=\frac{\∂y_c\left(t\right)}{\∂x_M\left(t\right)}=\frac{\∂y_c\left(t\right)/\∂t}{\∂x_M\left(t\right)/\∂t}=\frac{V_{c-y}\left(t\right)}{V_{c-x}\left(t\right)}$

Wherein：x_M(t)、V_c-xT () is respectively length travel and the longitudinal velocity that t automobile prolongs road direction；a_c-yGeneration Table represents from car lateral distance, x from car transverse acceleration, H_MRepresent from car length travel, tc represents passing time, Vc-y Represent from car lateral velocity, Vc-x represents from car longitudinal velocity, y_cRepresent lateral displacement.

Overtake other vehicles the condition that should possess and safety below for the majority of case discussion shown in Figure 12.Wherein, based on M Car, F is front vehicles, and L is the front vehicle on fast.For the situation shown in Figure 12, conservative driver may think that, There is car then should not overtake other vehicles on the fast of rear, and should take and travel with car (L car).Actually this is not so, if F and M, M and L it Between have sufficiently longitudinally (x direction) distance, then can overtake other vehicles.

Minimum longitudinal direction safe distance is discussed below when overtaking other vehicles between F and M, M and L, as shown in figure 13.

Defining point P is the intersection point in the M car upper left corner and F car lower limb tangent line.Obviously, point P is that two cars collide Boundary point.S is to overtake other vehicles the lateral separation of initial time F and M, and H is the displacement of targets completing of overtaking other vehicles.Due to formulaHave been presented for the displacement in the M upper right corner, then can be with M The displacement at other angles is as follows：

Yupper-left (t)=yc (t)-lM × sin (θ (t))

$\left\{\begin{array}{c}{y}_{lower-right}\left(t\right)=y_c\left(t\right)-w_M\×\cos \left(\mathrm{\θ}\right(t\left)\right)\\ y_{lower-left}\left(t\right)=y_c\left(t\right)-(l_M\×\sin (\mathrm{\θ}\left(t\right)+w_M\×\cos \left(\mathrm{\θ}\right(t\left)\right)\end{array}\right.$

Wherein：l_M、w_MIt is respectively M car length and width.

Should meet when reaching P point when the M car upper left corner：

y_c-l_M× sin (θ (t))=S

$y_c\left(t\right)-l_M\×\frac{V_{c-y}\left(t\right)}{\sqrt{V_{c-y}^2\left(t\right)+V_{c-x}^2\left(t\right)}}=S$

Such that it is able to show that the M car upper left corner reaches the time t of P point_p.

If as can be seen that the collision of F to be avoided and M is it is necessary to meet following condition：

$\begin{array}{cc}{x}_F\left(t\right)<x_M\left(t\right)-l_M\&times;cos\left(\mathrm{\&theta;}\right(t\left)\right)& \&ForAll;t\&Element;\&lsqb;t_p,\mathrm{\&infin;}\&rsqb;\end{array}$

Wherein：x_FT () is F car length travel.

In [t_p, ∞] and in the time period, as t >=t_cWhen, cos (θ (t)) obtains maximum, therefore, it can be reduced to：

$\begin{array}{cc}{x}_F\left(t\right)<x_M\left(t\right)-l_M& \&ForAll;t\&Element;\&lsqb;t_p,\mathrm{\&infin;}\&rsqb;\end{array}$

The afterbody of M car with the fore-and-aft distance of the head of F car is；

$\begin{array}{cc}{D}_{F-M}\left(t\right)=x_M\left(t\right)-l_M-x_F\left(t\right)& \&ForAll;t\&Element;\&lsqb;t_p,\mathrm{\&infin;}\&rsqb;\end{array}$

If to all t >=t_p, D_F-MT () ＞ 0, then will not collide.So having：

$\begin{array}{cc}{D}_{F-M}\left(t\right)=D_{F-M}\left(0\right)+{\&Integral;}_0^t{\&Integral;}_0^{\mathrm{\&tau;}}\left(a_{c-x}\right(\mathrm{\&lambda;})-a_F(\mathrm{\&lambda;}\left)\right)d\mathrm{\&lambda;}d\mathrm{\&tau;}+\left(V_F\right(0)-V_M(0\left)\right)\&CenterDot;t& \&ForAll;t\&Element;\&lsqb;t_p,\mathrm{\&infin;}\&rsqb;\end{array}$

Wherein：D_F-M(0) it is the two initial fore-and-aft distance.a_c-xLongitudinal acceleration when () is overtaken other vehicles for M car t, and count grind Study carefully and show：Generally, a_c-xT () is no more than 6m/s.a_FLongitudinal acceleration when () is overtaken other vehicles for F car t.

Make MD_F-MFor minimum longitudinal direction safe distance, then：

$\begin{array}{cc}{\mathrm{MD}}_{F-M}=\underset{t}{max}\&lsqb;{\&Integral;}_0^t{\&Integral;}_0^{\mathrm{\&tau;}}\left(a_F\right(\mathrm{\&lambda;})-a_{c-x}(\mathrm{\&lambda;}\left)\right)d\mathrm{\&lambda;}d\mathrm{\&tau;}+\left(V_M\right(0)-V_F\left(0\right)\&CenterDot;t\&rsqb;& \&ForAll;t\&Element;\&lsqb;t_p,\mathrm{\&infin;}\&rsqb;\end{array}$

In the same manner, make a_LLongitudinal acceleration when () is overtaken other vehicles for L car t can obtain the minimum safe distance between M and L：

$\begin{array}{cc}{\mathrm{MD}}_{M-L}=\underset{t}{max}\&lsqb;{\&Integral;}_0^t{\&Integral;}_0^{\mathrm{\&tau;}}\left(a_{c-x}\right(\mathrm{\&lambda;})-a_L(\mathrm{\&lambda;}\left)\right)d\mathrm{\&lambda;}d\mathrm{\&tau;}+\left(V_M\right(0)-V_L\left(0\right)\&CenterDot;t\&rsqb;& \&ForAll;t\&Element;\&lsqb;t_p,\mathrm{\&infin;}\&rsqb;\end{array}$

It can be seen that, minimum longitudinal direction safe distance depends on relative velocity, relative acceleration and time t_p.And this time Depend on lateral separation S, horizontal passing time t_c.Before and after assuming to overtake other vehicles, automobile is in the central authorities in track, then S is track Width.Thus, t_cIt is the key parameter of decision-making.

Different t_c, determine different overtaking processes.t_cLess, the fore-and-aft distance needed for overtaking process completes is shorter, but It is that the stationarity that overtaking process completes is poorer；Contrary t_cBigger, the fore-and-aft distance needed for overtaking process completes is longer, overtaking process The stationarity completing is better, but is susceptible to collision accident.Thus reasonably choose t_cHave great importance.Initial away from From D_F-M(0) under, t_cShould meet：

${\&Integral;}_0^t{\&Integral;}_0^{\mathrm{\&tau;}}{a}_{c-x}\left(\mathrm{\&lambda;}\right)d\mathrm{\&lambda;}d\mathrm{\&tau;}+V_M\left(0\right)\&CenterDot;t_c>\frac{1}{2}{a}_F\left(\mathrm{\&lambda;}\right)t_C^2+V_F\left(0\right)\&CenterDot;t_c-D_{F-M}\left(0\right)$

In the same manner, in initial distance D_M-L(0) under, t_cShould meet：

${\&Integral;}_0^t{\&Integral;}_0^{\mathrm{\&tau;}}{a}_{c-x}\left(\mathrm{\&lambda;}\right)d\mathrm{\&lambda;}d\mathrm{\&tau;}+V_M\left(0\right)\&CenterDot;t_c<\frac{1}{2}{a}_L\left(\mathrm{\&lambda;}\right)t_C^2+V_L\left(0\right)\&CenterDot;t_c+D_{M-L}\left(0\right)$

On the other hand, the safety of safety, driver and passenger to vehicle for the stable overtaking process and comfort level be extremely Close important.And the radius of curvature that overtaking process is produced directly determines the stationarity of overtaking process.Overtaking process radius of curvature is such as Shown in Figure 14.In figure, L_cRepresent the fore-and-aft distance completing needed for overtaking process, then： $L_c=\sqrt{4HR-H^2}$

For road design, there is corresponding technical standard various countries to R, and this standard is exactly vehicle safe driving When the radius of turn that must is fulfilled for.According to China《Highway technical standard》, it is 1200km/h, 100km/ in road speed When h, 80km/h, 60km/h, Limit infinitesimal radium is respectively：650m、400m、250m、125m.If R_minFor Limit infinitesimal radium, So：

$L_c>\sqrt{4{\mathrm{HR}}_{\min }-H^2}$

I.e.：

Thus,

${\&Integral;}_0^t{\&Integral;}_0^{\mathrm{\&tau;}}{a}_{c-x}\left(\mathrm{\&lambda;}\right)d\mathrm{\&lambda;}d\mathrm{\&tau;}+V_M\left(0\right)\&CenterDot;t_c>\frac{1}{2}{a}_F\left(\mathrm{\&lambda;}\right)t_C^2+V_F\left(0\right)\&CenterDot;t_c-D_{F-M}\left(0\right)$

${\&Integral;}_0^t{\&Integral;}_0^{\mathrm{\&tau;}}{a}_{c-x}\left(\mathrm{\&lambda;}\right)d\mathrm{\&lambda;}d\mathrm{\&tau;}+V_M\left(0\right)\&CenterDot;t_c<\frac{1}{2}{a}_L\left(\mathrm{\&lambda;}\right)t_C^2+V_L\left(0\right)\&CenterDot;t_c+D_{M-L}\left(0\right)$

${\&Integral;}_0^t{\&Integral;}_0^{\mathrm{\&tau;}}{a}_{c-x}\left(\mathrm{\&lambda;}\right)d\mathrm{\&lambda;}d\mathrm{\&tau;}+V_M\left(0\right)\&CenterDot;t_c>\sqrt{4{\mathrm{HR}}_{min}-H^2}$

Three above formula has together decided on t_cSpan.

t_cValue determine after, overtaking process and its corresponding parameter also determine that.Once current driving parameters are not Meet condition of overtaking other vehicles, system will provide warning, and propose the suggestion to current driving parameter adjustment.

The above, the only present invention preferably specific embodiment, but protection scope of the present invention is not limited thereto, Any those familiar with the art the invention discloses technical scope in, the change or replacement that can readily occur in, All should be included within the scope of the present invention.Therefore, protection scope of the present invention should be with scope of the claims It is defined.

Claims (15)

1. a kind of ultrasonic intelligent distance measurement alarm system is it is characterised in that include single chip control module, ultrasonic ranging mould Block, alarm module and display module, wherein：

Described single chip control module, in order to：

Counted by internal intervalometer, recorded ultrasonic emitting point time used by roundtrip propagation to barrier, And calculate the distance between barrier and ultrasonic emitting point；

The alarm threshold value of the distance between barrier and ultrasonic emitting point and described single chip control module internal preset is entered Row compares, and when the distance between barrier and ultrasonic emitting point are less than alarm threshold value, sends an alarm signal to described report Alert module；

Described ultrasonic distance measuring module is electrically connected with described single chip control module, in order to：

The pulse signal of described single chip control module output is launched, and receives ultrasonic echo signal and input to described Single chip control module；

Described alarm module is electrically connected with described single chip control module, in order to sent according to described single chip control module Alarm signal is reported to the police；

Described display module is electrically connected with described single chip control module, in order to show between ultrasonic emitting point and barrier Distance.

2. a kind of ultrasonic intelligent distance measurement alarm system according to claim 1 is it is characterised in that described ultrasonic ranging Module includes ultrasonic emitting circuit and ultrasound wave receiving circuit, wherein：

Described ultrasonic emitting circuit includes ultrasonic amplifier and ultrasonic emitting probe, and described ultrasonic amplifier will be described The pulse signal of single chip control module output is converted into mechanical wave through described ultrasonic emitting probe after being amplified and launches Go, described ultrasonic amplifier adopts 74LS04 amplifying circuit；

Described ultrasound wave receiving circuit includes ultrasound wave receiving transducer, integrated circuit CX20106A chip circuit, described ultrasound wave Receiving transducer receives the ultrasonic signal that the mechanical wave of described ultrasonic emitting probe transmitting reflects through barrier, described CX20106A chip circuit is in order to be amplified to the ultrasonic signal receiving, amplitude limit, bandpass filtering, peak detection, shaping, Relatively；

Described ultrasonic emitting probe and ultrasound wave receiving transducer are located in same level parallel lines, and distance between the two Between 5cm-8cm.

3. a kind of ultrasonic intelligent distance measurement alarm system according to claim 2 is it is characterised in that described ultrasonic emitting Probe, ultrasound wave receiving transducer, integrated circuit CX20106A chip circuit and 74LS04 amplifying circuit are integrated into a HR-SR04 Ultrasound wave integration module.

4. a kind of ultrasonic intelligent distance measurement alarm system according to claim 1 and 2 is it is characterised in that also include button Input module, described keyboard input module is connected with described single chip control module, in order to set alarm distance.

5. a kind of ultrasonic intelligent distance measurement alarm system according to claim 1 is it is characterised in that described display module is 4 common cathode charactrons.

6. a kind of ultrasonic intelligent distance measurement alarm system according to claim 1 is it is characterised in that described Single-chip Controlling Module is STC89C52 type single-chip microcomputer.

7. a kind of ultrasonic intelligent distance measurement alarm system according to claim 1 is it is characterised in that described alarm module is Buzzer.

8. a kind of follower's collision prevention method is it is characterised in that surveyed using the ultrasonic intelligent described in any one in claim 1-7 Away from warning system, its step includes：

Step 1：Test data in ultrasonic distance measuring module is received by single chip control module, and it is static or front to calculate front truck When side is barrier, from danger warning distance and the reminding alarm distance of car and front truck；

Step 2：When calculating front truck is at the uniform velocity exercised, from danger warning distance and the reminding alarm distance of car and front truck；

Step 3：When calculating front truck deceleration enforcement, from danger warning distance and the reminding alarm distance of car and front truck.

9. a kind of follower's collision prevention method according to claim 8 is it is characterised in that in step 1, front truck pass by apart from X₂ For 0, alarm distance d be from car pass by apart from X₁Plus safe spacing d₀Sum, specifically includes following steps：

Step 11：Calculate danger warning distance；

$X_1=v_1(t_a+\frac{t_s}{2})+\frac{v_1^2}{2a_1}$

Therefore,

Wherein, X₁Represent the distance passed by from car, unit is m；v₁Represent from vehicle speed, unit is m/s；t_aRepresent brake association Between timing, unit is s；t_sRepresent braking deceleration rise time, unit is s；a₁Represent from car braking deceleration, unit is m/ s²；d_bRepresent danger warning distance, unit is m；d₀Represent safe spacing, unit is m；

Step 12：Calculate reminding alarm distance；

$X_1=v_1(t_a+t_r+\frac{t_s}{2})+\frac{v_1^2}{2a_1}$

Therefore,

Wherein, t_rRepresent time of driver's reaction, unit is s；d_wRepresent reminding alarm distance, unit is m.

10. a kind of follower's collision prevention method according to claim 8 is it is characterised in that in step 2, alarm distance d adds front Car pass by apart from X₂Sum be equal to from car pass by apart from X₁Plus safe spacing d₀Sum, specifically includes following steps：

Step 21：Calculate danger warning distance；

X₁=s₁+s₂+s₃,

Wherein, X₁Represent the distance passed by from car, unit is s；s₁、s₂、s₃It is in reaction time of braking device t from car_a, braking deceleration Spend rise time t_s, time of driver's reaction t_rThe distance running in three time periods,

s₁=v₁t_a

Wherein, v₁Represent from vehicle speed, unit is m/s；

In braking deceleration rise time t_sEnd, from end speed v of car '₁For

$v_1^{,}=v_1-\frac{a_1}{2t_s}{t}^2$

Make t=t_s, then：

$v_1^{,}=v_1-\frac{a_1{t}_s}{2}$

Wherein, a₁Represent from car braking deceleration, unit is m/s²；

Being located at braking deceleration on dry pavement is 6m/s², t_sFor 0.2s, then

$v_1-v_1^{,}=\frac{a_1{t}_s}{2}$

Substitute into parameter, can calculate and come from car in t_sEnd speed will reduce 0.6m/s, when currently rear speed difference is less than 0.6m/s, from Car braking deceleration without reach maximum will be also lower than front vehicle speed from vehicle speed, if now from the increasing of car braking deceleration It is t ' for a long time,

$s_2={\&Integral;}_0^t(v_1-\frac{a_1}{2t_s}{t}^2)dt=v_1{t}^{,}-\frac{a_1{t}^{\mathrm{,3}}}{6t_s}$

$t^{,}=\sqrt{\frac{2v_{rel}{t}_s}{a_1}}$

$X_1=v_1{t}_a+v_1{t}^{,}-\frac{a_1{t}^{,3}}{6t_s}$

X₂=v₂t_a+v₂t’

Therefore,

Make v_rel=v₁-v₂

$d_b=v_{rel}(t_a+t^{,})-\frac{a_1{t}^{,3}}{6t_s}+d_0$

Wherein, v_relRepresent relative velocity, unit is m/s；X₂Represent the distance that front truck is passed by, unit is m；d_bRepresent danger warning Distance, unit is m；v₂Vehicle speed before representative, unit is m/s；d₀Represent safe spacing, unit is m；

After currently, speed is when differing by more than equal to 0.6m/s, will reach maximum existing from car braking deceleration and persistently make The dynamic time, if now from the car continuous braking time be t '_v,

$t_v^{,}=\frac{2v_{ref}-a_1{t}_s}{2a_1}$

$X_1=v_1(t_a+\frac{t_s}{2})+\frac{(2v_1{v}_{rel}-v_{rel}^2)}{2a_1}$

$X_2=v_2(t_a+t_s+t_v^{,})=v_2(t_a+\frac{t_s}{2}+\frac{v_{rel}}{a_1})$

Therefore, d_b=X₁-X₂+d₀

$d_b=v_{rel}(t_a+\frac{t_s}{2})+\frac{v_{rel}^2}{2a_1}+d_0$

Step 22：Calculate reminding alarm distance；

When after currently, speed difference is less than 0.6m/s,

$X_1=v_1(t_r+t_a)+v_1{t}^{,}-\frac{a_1{t}^{,3}}{6t_s}$

X₂=v₂(t_r+t_a)+v₂t’

$d_w=v_{rel}(t_a+t_r+t^{,})-\frac{a_1{t}^{,3}}{6t_s}+d_0$

When after currently, speed differs by more than equal to 0.6m/s,

$X_1=v_1(t_r+t_a+\frac{t_s}{2})|\frac{(2v_1{v}_{rel}-v_{rel}^2)}{2a_1}$

$X_2=v_2(t_r+t_a+t_s+t_v^{,})=v_2(t_r+t_a+\frac{t_s}{2}+\frac{v_{rel}}{a_1})$

$d_w=v_{rel}(t_r+t_a+\frac{t_s}{2})+\frac{v_{rel}^2}{2a_1}+d_0$

Wherein, d_wRepresent reminding alarm distance, unit is m.

A kind of 11. follower's collision prevention methods according to claim 8 are it is characterised in that in step 3, specifically include following step Suddenly：

Step 31：Calculate danger warning distance；

$X_1=v_1(t_a+\frac{t_s}{2})+\frac{v_1^2}{2a_1}$

$X_2=\frac{v_2{t}_s}{2}+\frac{v_2^2}{2a_2}$

$d_b+\frac{v_2{t}_s}{2}+\frac{v_2^2}{2a_2}=v_1(t_a+\frac{t_s}{2})+\frac{v_1^2}{2a_1}+d_0$

Make a₁=a₂=a, then

$d_b=v_1{t}_a+v_{rel}\frac{t_s}{2}+\frac{v_{rel}(2v_1-v_{ref})}{2a}+d_0$

Wherein, X₁Represent the distance passed by from car, unit is m；X₂Represent the distance that front truck is passed by, unit is m；v₁Represent from car Speed, unit is m/s；v₂Vehicle speed before representative, unit is m/s；v_relRepresent relative velocity, unit is m/s；t_aRepresent brake The coordination time, unit is s；t_sRepresent braking deceleration rise time, unit is s；a₁Represent from car braking deceleration, unit is m/s²；a₂Represent front truck braking deceleration, unit is m/s²；d₀Represent safe spacing, unit is m；d_bRepresent danger warning distance, Unit is m；

Step 32：Calculate reminding alarm distance；

$X_1=v_1(t_r+t_a+\frac{t_s}{2})+\frac{v_1^2}{2a_1}$

$X_2=\frac{v_2{t}_s}{2}+\frac{v_2^2}{2a_2}$

$d_w=v_1(t_r+t_a)+v_{rel}\frac{t_s}{2}+\frac{v_{rel}(2v_1-v_{ref})}{2a}+d_0$

Wherein, t_rRepresent time of driver's reaction, unit is s；d_wRepresent reminding alarm distance, unit is m.

A kind of 12. Lateral Collision Avoidance methods of overtaking other vehicles are it is characterised in that utilize the ultrasound wave described in any one in claim 1-7 Intelligent distance-measuring warning system, its step includes：

Step A：Test data in ultrasonic distance measuring module is received by single chip control module, and calculates and overtake other vehicles minimum from car Corner and fore-and-aft distance；

Step B：Calculate and overtake other vehicles hard-over and fore-and-aft distance from car；

Step C：Minimum safe distance when calculating is overtaken other vehicles.

13. one kind according to claim 12 overtake other vehicles Lateral Collision Avoidance method it is characterised in that step A specifically include following Calculation procedure：

$\frac{z}{\frac{y}{2}}=\frac{R}{2z},z=\frac{1}{2}\sqrt{yR},sin\frac{\mathrm{\&alpha;}}{2}=\frac{z}{R}=\frac{\frac{1}{2}\sqrt{yR}}{R}$

Wherein,

Make c_r=0,

$Lx=\frac{y}{yan\left(\frac{\mathrm{\&alpha;}}{2}\right)}$

Wherein, v₁Represent from vehicle speed, unit is m/s；a_cRepresent from car lateral acceleration, unit is m/s²；R represents revolution half Footpath, unit is m；Z represents lateral overtaking process and enters the 1/2 of displacement from garage, and unit is m；W₁Represent from vehicle-width, unit is m； W₂Vehicle-width before representative, unit is m；Y represents the sidesway distance from car centrage, and unit is m；α represents minimum corner, unit For °；c_rRepresent from the right side of car to safe spacing, unit is m；Lx represents fore-and-aft distance during minimum corner from car and front truck, single Position is m.

14. one kind according to claim 12 overtake other vehicles Lateral Collision Avoidance method it is characterised in that step B specifically include following Calculation procedure：

$\frac{z}{\frac{y}{2}}=\frac{R}{2z},z=\frac{1}{2}\sqrt{yR},sin\frac{\mathrm{\&beta;}}{2}=\frac{z}{R}=\frac{\frac{1}{2}\sqrt{yR}}{R}$

Wherein,

Make c₁=0,

$Ld=\frac{y}{tan\left(\frac{\mathrm{\&beta;}}{2}\right)}$

Wherein, v₁Represent from vehicle speed, unit is m/s；a_cRepresent from car lateral acceleration, unit is m/s²；R represents revolution half Footpath, unit is m；Z represents lateral overtaking process and enters the 1/2 of displacement from garage, and unit is m；W₁Represent from vehicle-width, unit is m； L represents lane width, and unit is m；Y represents the sidesway distance from car centrage, and unit is m；β represents hard-over, unit For °；c_lRepresent from the left of car to safe spacing, unit is m；Ld represents fore-and-aft distance during hard-over from car and front truck, single Position is m.

15. one kind according to claim 12 overtake other vehicles Lateral Collision Avoidance method it is characterised in that step C specifically include following Calculation procedure：

Assume that vehicle starts to overtake other vehicles in the t=0 moment, in 0～t_cIn time period, application transverse acceleration completes overtaking process, with vapour The upper right corner of car M be reference point, lateral distance be H, then at H/2, the lateral velocity of automobile reach maximum it is assumed that Overtaking process is steady, then, v_c-yMeet sine wave characteristics, then the transverse acceleration of automobile meets a_c-yCosine wave property, if：

a_c-y(t)=A*sin (ω t+ pi/2) (0≤t≤t_c)

Wherein：A is undetermined coefficient, ω=2 π/t_c

Thus having：

${\&Integral;}_0^{t_c}{\&Integral;}_0^{t}A\sin (\mathrm{\&omega;}t-\mathrm{\&pi;}/2)d\mathrm{\&tau;}dt=H$

Obtain：So：

$\begin{array}{cc}{a}_{c-y}\left(t\right)=\frac{2\mathrm{\&pi;}H}{t_c^2}sin(\frac{2\mathrm{\&pi;}}{t_c}t-\frac{\mathrm{\&pi;}}{2})& (0\&le;t\&le;t_c)\end{array}$

On the other hand, during automobile overtaking, transverse acceleration comes from the cross stream component of direct of travel acceleration, if t Automobile direct of travel is θ (t) in the longitudinal angle of road, has：

$tan\left(\mathrm{\&theta;}\right(t\left)\right)=\frac{\&part;y_c\left(t\right)}{\&part;x_M\left(t\right)}=\frac{\&part;y_c\left(t\right)/\&part;t}{\&part;x_M\left(t\right)/\&part;t}=\frac{V_{c-y}\left(t\right)}{V_{c-x}\left(t\right)}$

Wherein：x_M(t)、V_c-xT () is respectively length travel and the longitudinal velocity that t automobile prolongs road direction；a_c-yRepresent from car Transverse acceleration, H represents from car lateral distance, x_MRepresent from car length travel, tc represents passing time, Vc-y represents certainly Car lateral velocity, Vc-x represents from car longitudinal velocity, y_cRepresent lateral displacement.