CN109917411B - Obstacle detection device and method based on laser ranging and triaxial accelerometer - Google Patents

Abstract

The invention relates to an obstacle detection device and method based on laser ranging and a three-axis accelerometer, belonging to the field of signal detection. The device includes a laser ranging module, a three-axis accelerometer, and a processing and computing module; the user of the laser ranging module measures and acquires the distance from the light spot to the system substrate; Acceleration values in three directions; the processing and calculation module is used to calculate, correct and compare the data acquired by the laser ranging module and the three-axis accelerometer, to obtain the relationship with the warning threshold, and to judge whether a certain orientation is There are obstacles. Compared with the traditional detection device, the device of the present invention has simple structure, low cost, low energy consumption and strong real-time performance; it can form a complete system independently, operate independently, or be integrated to operate on existing equipment.

Description

Obstacle detection device and method based on laser ranging and three-axis accelerometer

technical field

The invention belongs to the technical field of signal detection, and relates to an obstacle detection device and method based on laser ranging and a three-axis accelerometer.

Background technique

Today, due to the popularization of smart devices (such as smart phones), more and more head-hunting people have appeared. However, playing with mobile phones while walking has many potential hazards, such as falling down steps. There have been many cases of such injuries. Therefore, the study of road obstacle detection technology has good practical value and social value.

At present, commonly used obstacle detection devices mainly include the following types:

(1) Obstacle detection device based on the visual image of the monocular camera: using machine learning technology to segment and identify obstacles from the image, this method is costly and requires a large processor computing power; using optical flow or dynamic Image recognition obstacles, this method has high cost, poor real-time performance and consumes a lot of computing power.

(2) Obstacle detection device based on the visual image of the multi-eye camera: the depth information of the image can be obtained by using the binocular or multi-eye camera, and then the foreground and background can be distinguished and obstacles can be identified. This method is more costly. Moreover, the performance of the above-mentioned methods using a camera is subject to external light conditions.

(3) Obstacle detection device based on laser radar: the precise distance and orientation information of surrounding objects can be obtained by laser ranging and rotating the laser transmitter. This method is extremely expensive and consumes a lot of energy, so it is not suitable for embedded equipment.

(4) Simple single-beam laser distance measuring device: By modulating the phase information on the light wave, the distance between the laser transmitter and the obstacle is obtained by calculating the phase difference. The cost is low and the calculation complexity is low, and the device has strong real-time performance. However, in a dynamic device, it is difficult to determine the pointing of the laser at a certain moment, and its ranging information cannot be effectively used for obstacle detection.

Therefore, inventing a device that can effectively detect steps and issue an alarm when walking has better practical value and social value.

Contents of the invention

In view of this, the object of the present invention is to provide an obstacle detection device and method based on laser ranging and three-axis accelerometer, which combines directional laser ranging and three-axis accelerometer, and uses the signal of three-axis accelerometer to correct the laser measurement. By dynamically monitoring the corrected laser ranging information, it is more effective to detect obstacles in a certain orientation.

To achieve the above object, the present invention provides the following technical solutions:

An obstacle detection device based on laser ranging and a three-axis accelerometer, including a laser ranging module, a three-axis accelerometer, and a processing and computing module; wherein, the laser ranging module and the three-axis accelerometer are fixed on the system substrate above; the processing and computing module is flexibly connected to the system substrate;

The laser beam emitted by the laser ranging module is perpendicular to the system substrate, and the phase difference between the laser spot and the system substrate is calculated by using the phase difference by generating laser light and detecting the phase difference;

The three-axis accelerometer is used to acquire acceleration values g _x , g _y , and g _z in the three directions of x-axis, y-axis and z-axis, wherein the plane where the x-axis and y-axis are located is parallel to the system substrate;

The processing calculation module is used to calculate, correct and compare the data acquired by the laser ranging module and the three-axis accelerometer, obtain the relationship with the warning threshold, and judge whether there is an obstacle in a certain direction.

Further, the device also includes an alarm module, which alarms according to the alarm signal obtained from the processing and calculation module, that is, alarms when there is an obstacle.

Further, the alarm signal is transmitted to the user in the form of sound, light or vibration, and the alarm signal generated by the processing and computing module will be output to the alarm module through the I/O pin of the processor, such as sound alarm, flash alarm, screen information prompt alarm, vibration Alarm or a combination of the above.

Further, according to an obstacle detection method based on laser ranging and three-axis accelerometer according to the device: the laser ranging information is corrected by using the triaxial accelerometer signal, and the corrected laser ranging information is more effectively detected by dynamic monitoring Obstacles in a certain direction, specifically include the following steps:

S1: Select the location of the laser ranging module as the measurement base point, and select the point formed by the intersection of the laser beam and the plane to be measured when 0°≤α ₀ < arccos(h/M) as the measurement reference point, where α ₀ is the location of the system substrate The angle between the plane and the plane to be measured, h is the vertical distance from the measurement base point to the plane to be measured, and M is the maximum working distance of the laser ranging;

S2: The actual distance r from the measurement base point to the measurement reference point measured by the laser ranging module;

S3: Obtain the acceleration values g _x , g y , g _z of the three axes x-axis, y _- axis, and z-axis of the three-axis accelerometer;

S4: Calculate the correction distance;

S5: The processing calculation module compares the measurement results of multiple measurement cycles to determine whether there is an obstacle on the plane to be measured.

Further, in the step S4, the specific steps for calculating the correction distance are:

其中

S41: Calculate the angle between the system substrate and the plane to be measured according to the acceleration value

in

S42: Use trigonometric functions to calculate the vertical distance L _h = r × cosα from the measurement base point to the plane to be measured, or the distance between the measurement base point and the measurement reference point

Further, the step S5 specifically includes: after the laser ranging module selects the measurement base point, keep the angle α between the system substrate and the plane to be measured unchanged, and the module measures the measurement base point B and the measurement reference point at time T The distance between R is L _r0 , after any time t, that is, at time T+t, the distance between the measurement base point B and the measurement reference point R is L _r1 , if there is a significant change in the value of L _r0 and L _r1 , it indicates that there are fluctuations in the plane to be measured, that is, there may be obstacles, and the alarm system will issue a warning at this time.

Further, the sign of significant change is defined as rate=(L _r1 -L _r0 )/L _r0 , through the preset or user-set warning threshold θ, when rate≥θ, the alarm module sends out an alarm signal, indicating that There are obstacles on the road; otherwise, no alarm will be given, indicating that there are no obstacles on the road.

The beneficial effect of the present invention is that: the present invention combines the directional laser ranging and the three-axis accelerometer, uses the three-axis accelerometer signal to correct the laser ranging information, and detects a certain orientation more effectively by dynamically monitoring the corrected laser ranging information of obstacles. Compared with traditional devices in the same application field, it has the advantages of simple structure, low cost, low energy consumption and strong real-time performance.

The present invention can also be realized by part of the hardware of existing handheld devices, such as mobile phones, and can also form a complete system independently, run independently, or be integrated to run on existing devices.

Other advantages, objects and features of the present invention will be set forth in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the investigation and research below, or can be obtained from It is taught in the practice of the present invention. The objects and other advantages of the invention may be realized and attained by the following specification.

Description of drawings

In order to make the purpose of the present invention, technical solutions and advantages clearer, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

Fig. 1 is a schematic diagram of the internal structure of the detection device of the present invention;

Fig. 2 is the schematic diagram when the detection device of the present invention works;

Fig. 3 is a flow chart of the detection method of the detection device of the present invention;

FIG. 4 is a schematic diagram of step detection when the device is held in hand.

Detailed ways

Embodiments of the present invention are described below through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific implementation modes, and various modifications or changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the diagrams provided in the following embodiments are only schematically illustrating the basic concept of the present invention, and the following embodiments and the features in the embodiments can be combined with each other in the case of no conflict.

Wherein, the accompanying drawings are for illustrative purposes only, and represent only schematic diagrams, rather than physical drawings, and should not be construed as limiting the present invention; in order to better illustrate the embodiments of the present invention, some parts of the accompanying drawings may be omitted, Enlargement or reduction does not represent the size of the actual product; for those skilled in the art, it is understandable that certain known structures and their descriptions in the drawings may be omitted.

Please refer to Figures 1 to 4, Figure 1 is an obstacle detection device based on laser ranging and three-axis accelerometer according to the present invention, which mainly consists of three hardware modules: laser ranging module, three-axis accelerometer, processing calculation module. These three modules need to be fixed or flexibly connected to the substrate of the device. When flexibly connecting, it is necessary to ensure that the relative position of the laser ranging module and the three-axis accelerometer and the attitude in the space are stable. Fig. 2 is a schematic diagram of the device of the present invention in operation, wherein the laser beam is perpendicular to the system substrate; Fig. 3 is a working flow chart of the detection device of the present invention.

1) Laser ranging module:

The laser ranging module generates laser light and detects the phase difference of the light spot, and uses the phase difference to calculate the distance from the light spot to the system. In the present invention, the laser beam is perpendicular to the system substrate, and the intersection of the straight line where the laser beam is located and the plane where the system substrate is located is called the measurement base point. Compared with the measurement distance, the substrate thickness and the thickness and volume of the laser module can be ignored, so for the convenience of description, the position of the laser module can be considered as the measurement base point.

的圆形范围内待测平面的任一点，其中h为测量基点到待测平面的垂直距离，h小于M。例如可以选取系统基板所在平面与平整地面夹角为α₀＝45°时激光束与平整地面相交的点为测量参考点；更普适地，在一次完整的测量过程中，可以选取任意0°≤α₀＜arccos(h/M)时激光束与待测平面相交形成的点为测量参考点。When measuring distance, this module will measure the distance between the measurement base point and the reference point. When detecting obstacles, a point on the flat ground can be selected as a reference point, and the existence of obstacles can be judged by monitoring the distance change between the measurement base point and the reference point at different times. When the maximum working distance of the laser ranging is M, the selection range of the reference point is: the projection point S of the measurement base point on the plane to be measured is the center of the circle, and the radius

Any point on the plane to be measured within the circular range of , where h is the vertical distance from the measurement base point to the plane to be measured, and h is less than M. For example, the point where the laser beam intersects the flat ground can be selected as the measurement reference point when the angle between the plane where the system substrate is located and the flat ground is α ₀ =45°; more generally, any 0° can be selected during a complete measurement process When ≤α ₀ < arccos(h/M), the point formed by the intersection of the laser beam and the plane to be measured is the measurement reference point.

2) Three-axis accelerometer:

Since the angle α between the system substrate and the plane to be measured is not fixed, for example, the angle between the system and the plane to be measured may change as the state of motion changes when the system is in a hand-held state. For an ideal laser ranging module, when the angle α approaches 90 degrees from 0 degrees, the measured r value is gradually approaching +∞ from the distance between the system and the plane to be measured from h. For the actual laser ranging module, the r value It will gradually approach the maximum working distance M of the laser ranging module from h. Since the system sends out an alarm, it needs to compare the distance measurement results between the measurement base point and the fixed angle reference point, so it is necessary to correct the measurement deviation caused by the different included angles.

The correction process is divided into three steps:

a. Obtain the acceleration values g _x , g y , g _z of the three axes x-axis, y _- axis, and z-axis of the three-axis accelerometer;

b. Calculate the angle α between the system substrate and the plane to be measured according to the acceleration value;

c. Use trigonometric functions to calculate the vertical distance L _h between the measurement base point on the system substrate and the reference plane, or the distance L _r between the measurement base point and the measurement reference point when any other fixed α _r is given.

L_h＝r×cosα，

As shown in Figure 2, the side EB is the x-axis, and the side BR is the z-axis, where the plane determined by the x and y axes is parallel to the plane where the system substrate is located, and the positive direction of the z-axis is parallel to the direction of the laser beam. So

L _h = r × cos α,

此后利用合向量和g_z计算

此后计算过程与前述相同，即L_h＝r×cosα，

When considering the pitch angle α and the roll angle β at the same time, it needs to be calculated by the values of g _x , g _y , and g _z . First, the resultant vector along the plane of the system substrate is calculated by g _x and g _y

Thereafter, using the combined vector and g _z to calculate

After that, the calculation process is the same as above, that is, L _h =r×cosα,

3) Processing calculation module:

This module is used to complete the above calculation process and send out alarm signals. An ARM processor is adopted, but the calculation module is not limited to the ARM processor. The signals collected by the laser ranging module and the three-axis accelerometer are handed over to the processing and computing module to complete the acquisition and quantification. Follow the above process to complete the distance calculation and complete the correction of the measurement difference caused by the system attitude.

This module is responsible for the generation and management of the monitoring cycle, that is, managing when to initialize several other modules, when to start the acquisition process, when to obtain the acquisition results, and when to compare the measurement results of multiple cycles.

The most important task of this module is to compare the measurement results of multiple measurement cycles to determine whether there are obstacles on the plane to be measured. After the measurement base point is selected by the laser ranging module, the angle α between the system substrate and the plane to be measured is kept unchanged. The module measures the distance between the measurement base point B and the reference point R at time T as L _r0 , any After time t, that is, T+t time, the distance between the measurement base point B and the reference point R is L _r1 , if there is a significant change in the value of L _r0 and L _r1 , it indicates that there are fluctuations in the plane to be measured, that is, there may be obstacle, the alarm system will issue a warning. Significant changes can be defined as rate=(L _r1 -L _r0 )/L _r0 , through a pre-set or user-set warning threshold θ, an alarm signal is issued when rate≥θ.

The alarm signal can be transmitted to the user in the form of sound, light or vibration. The alarm signal generated by this module will be output to the subsequent module that implements the alarm function through the IO pin of the processor, such as sound alarm, flash alarm, screen information prompt alarm, vibration alarm or a combination of the above.

As shown in Figure 4, a typical working scene of this device: when the device is held in hand, the step detection is carried out. When the person holding the device encounters a step, due to a sudden change in the distance measurement, the alarm module will send out an alarm reminder. This reminds walking personnel to pay attention to the steps and avoid accidents such as falls.

Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements, without departing from the spirit and scope of the technical solution, should be included in the scope of the claims of the present invention.

Claims (5)

1. A barrier detection device based on laser ranging and a triaxial accelerometer is characterized by comprising a laser ranging module, a triaxial accelerometer and a processing and calculating module; the laser ranging module and the triaxial accelerometer are fixed on a system substrate, and the processing and calculating module is flexibly connected to the system substrate;

the laser beam emitted by the laser ranging module is vertical to the system substrate, and the distance from the light spot to the system substrate is calculated by utilizing the phase difference through generating laser and detecting the phase difference of the light spot;

the three-axis accelerometer is used for acquiring and acquiring acceleration values g in three directions of an x axis, a y axis and a z axis _x ,g _y ,g _z Wherein the plane of the x axis and the plane of the y axis are parallel to the system substrate;

the processing and calculating module is used for calculating, correcting and comparing data acquired by the laser ranging module and the triaxial accelerometer to obtain the relation between the data and a warning threshold value and judge whether an obstacle exists in a certain direction;

the detection method of the device is to utilize the triaxial accelerometer signal to correct the laser ranging information and detect the barrier in a certain direction by dynamically monitoring the corrected laser ranging information, and specifically comprises the following steps:

s1: selecting the position of a laser ranging module as a measurement base point, and selecting a point formed by the intersection of a laser beam and a plane to be measured as a measurement reference point;

s2: the actual distance r from the measurement base point to the measurement reference point is measured by the laser ranging module;

s3: acquiring acceleration values g of three axes of an x axis, a y axis and a z axis of a three-axis accelerometer _x ,g _y ,g _z ；

S4: calculating the correction distance, which comprises the following specific steps:

s41: calculating the included angle between the system substrate and the plane to be measured according to the acceleration value

Wherein->

S42: calculating the vertical distance L between the measuring base point and the plane to be measured by utilizing a trigonometric function _h = r × cos α, or any other given fixed angle α _r While measuring the distance between the base point and the reference point

S5: the processing and calculating module compares the measuring results of the measuring periods so as to judge whether the plane to be measured has the obstacles or not.

2. The obstacle detection device based on the laser ranging and the triaxial accelerometer as claimed in claim 1, further comprising an alarm module for alarming according to the alarm signal obtained from the processing and calculating module, i.e. alarming when there is an obstacle.

3. The obstacle detection device based on laser ranging and triaxial accelerometer of claim 2, wherein the alarm signal is transmitted to the user through sound and light or vibration, and the alarm signal generated by the processing and calculating module is outputted to the alarm module through the I/O pin of the processor.

4. The obstacle detection device based on laser ranging and three-axis accelerometer according to claim 1, wherein the step S5 specifically comprises: after the laser ranging module selects a measurement base point, keeping an included angle alpha between a system substrate and a plane to be measured unchanged, and measuring by the module at the moment T to obtain a distance L between the measurement base point B and a measurement reference point R _r0 After an arbitrary time T, i.e. at time T + T, the distance between the measurement base B and the measurement reference R is L _r1 If L is _r0 And L _r1 If the value of the data is changed obviously, the fact that the plane to be measured fluctuates indicates that an obstacle possibly exists, and at the moment, the alarm system gives an alarm.

5. The laser ranging and triaxial accelerometer-based obstacle detection device according to claim 4, wherein the significantly changed flag is defined as rate = (L) _r1 -L _r0 )/L _r0 When the rate is larger than or equal to theta through a preset warning threshold theta or a warning threshold theta set by a user, an alarm moduleThe block sends out an alarm signal to indicate that the road surface has an obstacle; otherwise, no alarm is given, and the road surface is free of obstacles.

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