CN105523084A - Method for detecting turning angle of vehicle based on three-axis acceleration sensor - Google Patents

Abstract

The invention relates to the field of vehicle monitoring and particularly relates to a method for detecting the turning angle of a vehicle based on a three-axis acceleration sensor. The method for detecting the turning angle of the vehicle based on the three-axis acceleration sensor, disclosed by the invention, comprises the following steps: firstly, calibrating the initial state of the three-axis acceleration sensor; then, acquiring acceleration vector data of the three-axis acceleration sensor, calculating an acceleration vector component Af in the advancing direction of the vehicle and a lateral acceleration vector component Aw in the direction perpendicular to the advancing direction of the vehicle, and acquiring an advancing speed vector V of the vehicle at the same moment; and then, calculating a turning angle theta i of the vehicle within the time delta t according to the acceleration vector component Af, the lateral acceleration vector component Aw and the advancing speed vector V, thereby calculating a total turning angle theta total in the whole turning process. The method provided by the invention is low in cost and simple and convenient to implement, and the accuracy also can meet the requirement on practical application.

Description

A kind of method detecting vehicle angle of turn based on 3-axis acceleration sensor

Technical field

The invention belongs to vehicle monitoring field, relate to a kind of method detecting vehicle angle of turn based on 3-axis acceleration sensor particularly.

Background technology

Along with the development of society, the raising of people's living standard, the quantity of automobile gets more and more, and increasing of automobile quantity also causes traffic accident to increase, in traffic accident treatment process, driving states when having an accident is then a kind of very important analysis means, may be used for whether in violation of rules and regulations analyzing driving behavior, and driving states comprises anxious acceleration, anxious deceleration, sharply turning etc.On the other hand, along with the development of car networking industry, based on vehicle OBD (onboard diagnostic system) or CAN (controller local area network) interface access vehicle interior bus, and the use of the car-mounted terminal of band location and radio communication on vehicle is more and more extensive, and its main purpose is for vehicle condition data acquisition, driver driving behavioral value and running data collection and report etc.Wherein, driving behavior comprises anxious acceleration, anxious deceleration, sharply turning, sudden stop etc.; Detect sharply turning, usual needs incidentally detect the angle of turn inside diameter, and current existing scheme adopts gyroscope device to realize angle of turn and angular velocity detection usually, and as publication: CN102211612A, although implement comparatively simple, cost is higher.

Summary of the invention

The object of the invention is as solving the problem and provides a kind of testing cost low, realizes the easy method detecting vehicle angle of turn based on 3-axis acceleration sensor.

The invention discloses a kind of method detecting vehicle angle of turn based on 3-axis acceleration sensor, comprise the steps:

A10, carries out initial condition demarcation to 3-axis acceleration sensor.

A20, obtains the acceleration data of 3-axis acceleration sensor, calculates the acceleration component on vehicle direct of travel with at the lateral acceleration vector component perpendicular to vehicle direct of travel obtain the gait of march vector of vehicle in the same time

A30, according to acceleration component lateral acceleration vector component with gait of march vector calculate the angle θ of vehicle in Δ t time inside turn _i, its computing formula is

${\mathrm{\θ}}_i=arcsin\left(\frac{\left|{\stackrel{\→}{A}}_w\right|\·\mathrm{\Δ}t}{\sqrt{{\left(\right|{\stackrel{\→}{A}}_w|\·\mathrm{\Δ}t)}^2+{\left(\right|\stackrel{\→}{V}+\stackrel{\→}{A_f}\·\mathrm{\Δ}t\left|\right)}^2}}\right)$

Further, also comprise steps A 40, detect the angle of turn that once turning process is total, concrete grammar is:

When lateral acceleration vector component >=setting threshold M, starts to carry out angle detection, when lateral acceleration vector component < setting threshold M or lateral acceleration vector component direction when undergoing mutation, angle at the end detects, then the angle of turn that once turning process is total is wherein, θ _ibe the angle of turn in i-th Δ t time, n=t/ Δ t round numbers, t is this turning process duration.

Further, described lateral acceleration vector component the direction determination methods of undergoing mutation be: calculate $\mathrm{mod}1=|{{\stackrel{\&RightArrow;}{A}}_w}^{\&prime;}-{\stackrel{\&RightArrow;}{A}}_w|.$ With $\mathrm{mod}2=|{{\stackrel{\&RightArrow;}{A}}_w}^{\&prime;}+{\stackrel{\&RightArrow;}{A}}_w|,$ If mod1>mod2, then with oppositely, namely direction there occurs sudden change, wherein, with for adjacent two lateral acceleration vector components.

Further, in described steps A 10, initial condition is demarcated and is comprised gravity effect vector demarcate and vehicle direct of travel vector demarcate.

Further, in described steps A 20, the gait of march vector of vehicle mould obtained by vehicle OBD or CAN, direction is by vehicle direct of travel vector determine.

Advantageous Effects of the present invention:

The present invention adopts three axle acceleration sensors to judge sharply turning, and calculates angle of turn, than gyroscope etc., greatly reduces cost low; And easy being easy to realizes, design accuracy can meet the requirement of general application scenarios.

Accompanying drawing explanation

Fig. 1 is the diagram of circuit of the embodiment of the present invention;

Fig. 2 is three axle decomposing schematic representations of embodiment of the present invention resultant acceleration;

Fig. 3 is that the angle of turn of the embodiment of the present invention calculates schematic diagram;

Fig. 4 is adjacent two lateral acceleration vectors schematic diagram in the same way of the embodiment of the present invention;

Fig. 5 is two adjacent reverse schematic diagrams of lateral acceleration vector of the embodiment of the present invention.

Detailed description of the invention

Now the present invention is further described with detailed description of the invention by reference to the accompanying drawings.

As shown in Fig. 1 to 5, a kind of method detecting vehicle angle of turn based on 3-axis acceleration sensor, comprises the steps:

A10, carries out initial condition demarcation to 3-axis acceleration sensor.

In this specific embodiment, 3-axis acceleration sensor can be pressure resistance type 3-axis acceleration sensor, piezoelectric type 3-axis acceleration sensor or capacitance-type triaxial acceleration pick-up, carries out initial condition calibration to it, comprises gravity effect vector demarcate and vehicle direct of travel vector demarcate, concrete grammar is:

Gravity effect vector demarcate: vehicle is parked on level road, and the acceleration data repeatedly under read level quiescence, get arithmetic average and be stored in nonvolatile memory.

Vehicle direct of travel vector demarcate: vehicle starts to give it the gun forward, (certainly, in other embodiments, 5km/h is not limited to when reading first speed >5km/h, can be set according to actual conditions by technical personnel) time acceleration, be demarcated as vehicle direct of travel vector and be stored in nonvolatile memory.

A20, obtains the acceleration data of 3-axis acceleration sensor, calculates the acceleration component on vehicle direct of travel with at the lateral acceleration vector component perpendicular to vehicle direct of travel obtain the gait of march vector of vehicle in the same time

Concrete, (Δ t value is less every the Δ t time for processing unit (being micro controller system or MCU treater in the present embodiment), then result of calculation is more accurate, but consider actual conditions and computational complexity, Δ t can not obtain too little, this is concrete implements, and Δ t value is 200ms) read the real-time resultant acceleration vector of a 3-axis acceleration sensor calculate the acceleration component of advancing on horizontal surface at vehicle acceleration component on vehicle direct of travel with at the lateral acceleration vector component perpendicular to vehicle direct of travel computation process is as follows:

${\stackrel{\&RightArrow;}{A}}_s=\stackrel{\&RightArrow;}{A}-\stackrel{\&RightArrow;}{G}$

${\stackrel{\&RightArrow;}{A}}_f=\left|{\stackrel{\&RightArrow;}{A}}_s\right|\&CenterDot;cos\mathrm{\&alpha;}\&CenterDot;\frac{{\stackrel{\&RightArrow;}{A}}_{f0}}{\left|{\stackrel{\&RightArrow;}{A}}_{f0}\right|}=\frac{{\stackrel{\&RightArrow;}{A}}_s\&CenterDot;{\stackrel{\&RightArrow;}{A}}_{f0}}{\left|{\stackrel{\&RightArrow;}{A}}_{f0}\right|}\&CenterDot;\frac{{\stackrel{\&RightArrow;}{A}}_{f0}}{\left|{\stackrel{\&RightArrow;}{A}}_{f0}\right|}$

${\stackrel{\&RightArrow;}{A}}_w={\stackrel{\&RightArrow;}{A}}_s-{\stackrel{\&RightArrow;}{A}}_f$

Wherein, α is acceleration component with acceleration component angle, as shown in Figure 2.

Obtain the gait of march vector of vehicle in the same time concrete grammar be: processing unit is by the gait of march vector of vehicle OBD or CAN (certainly, in other embodiments, alternate manner also can being adopted to obtain, obtaining as adopted speed sensor) reading vehicle mould, and to give vehicle direct of travel be its direction vector, namely obtains gait of march vector

A30, according to acceleration component lateral acceleration vector component with gait of march vector calculate the angle θ of vehicle in Δ t time inside turn _i.Inventor, after studying with keen determination, calculates:

with relation as shown in Figure 3, the angle θ of turn inside diameter within the Δ t time can be calculated according to Fig. 3 _i:

${\mathrm{\&theta;}}_i=arcsin\left(\frac{\left|{\stackrel{\&RightArrow;}{A}}_w\right|\&CenterDot;\mathrm{\&Delta;}t}{\sqrt{{\left(\right|{\stackrel{\&RightArrow;}{A}}_w|\&CenterDot;\mathrm{\&Delta;}t)}^2+{\left(\right|\stackrel{\&RightArrow;}{V}+{\stackrel{\&RightArrow;}{A}}_f\&CenterDot;\mathrm{\&Delta;}t\left|\right)}^2}}\right)$

Wherein, for with the gait of march vector of the vehicle of interval of delta t time, m is the quality of sensor.

A40, the angle of turn θ that the once turning process that detects is total _total, concrete grammar is:

When lateral acceleration vector component (in the present embodiment, M is 500mm/s to>=setting threshold M ²certainly, in other embodiments, the value of M can be set according to actual needs by technical personnel, the object arranging M is to avoid some invalid computation, alleviates the calculated amount of processing unit), start to carry out angle detection, every Δ t time detecting angle of turn, until lateral acceleration vector component < setting threshold M or lateral acceleration vector component direction when undergoing mutation, angle at the end detects, then the angle of turn that once turning process is total wherein, θ _ibe the angle of turn in i-th Δ t time, n=t/ Δ t round numbers, t is the time length of process of once turning.

Concrete, lateral acceleration vector component the direction determination methods of undergoing mutation be: calculate with if mod1<mod2, then with in the same way, as shown in Figure 4; If mod1>mod2, then with oppositely, as shown in Figure 5, namely direction there occurs sudden change, wherein, with for adjacent two lateral acceleration vector components.

In addition, by by lateral acceleration vector component compare with setting threshold, if lateral acceleration vector component be greater than setting threshold, then can be judged as sharply turning, can judge whether vehicle carries out sharply turning by 3-axis acceleration sensor very easily.

Although specifically show in conjunction with preferred embodiment and describe the present invention; but those skilled in the art should be understood that; not departing from the spirit and scope of the present invention that appended claims limits; can make a variety of changes the present invention in the form and details, be protection scope of the present invention.

Claims (5)

1. detect a method for vehicle angle of turn based on 3-axis acceleration sensor, it is characterized in that, comprise the steps:

A10, carries out initial condition demarcation to 3-axis acceleration sensor;

A20, obtains the acceleration data of 3-axis acceleration sensor, calculates the acceleration component on vehicle direct of travel with at the lateral acceleration vector component perpendicular to vehicle direct of travel obtain the gait of march vector of vehicle in the same time

A30, according to acceleration component lateral acceleration vector component with gait of march vector calculate the angle θ of vehicle in Δ t time inside turn _i, its computing formula is

。

2. the method detecting vehicle angle of turn based on 3-axis acceleration sensor according to claim 1, it is characterized in that: also comprise steps A 40, detect the angle of turn that once turning process is total, concrete grammar is:

start to carry out angle detection, or lateral acceleration vector component direction when undergoing mutation, angle at the end detects, then the angle of turn that once turning process is total is wherein, θ _ibe the angle of turn in i-th Δ t time, n=t/ Δ t round numbers, t is this turning process duration.

3. the method detecting vehicle angle of turn based on 3-axis acceleration sensor according to claim 2, is characterized in that: described lateral acceleration vector component the direction determination methods of undergoing mutation be: calculate with if mod1>mod2, then with oppositely, namely direction there occurs sudden change, wherein, with for adjacent two lateral acceleration vector components.

4. the method detecting vehicle angle of turn based on 3-axis acceleration sensor according to claim 1, is characterized in that: in described steps A 10, and initial condition is demarcated and comprised gravity effect vector demarcate and vehicle direct of travel vector demarcate.

5. the method detecting vehicle angle of turn based on 3-axis acceleration sensor according to claim 1, is characterized in that: in described steps A 20, the gait of march vector of vehicle mould obtained by vehicle OBD or CAN, direction is by vehicle direct of travel vector determine.