阅读说明：本技术 基于杂波分析的草地识别方法 (Grassland identification method based on clutter analysis ) 是由 刘瑜 于 2020-05-04 设计创作，主要内容包括：本发明公开一种基于杂波分析的草地识别方法,包括可以自主移动的运动平台,所述的运动平台内部设置处理器,所述的运动平台底部安装超声波发射模块和超声波接收模块,所述的处理器内部设置草地识别算法,确认所述的运动平台所在位置是否为草地,所述的草地识别算法包括以下步骤：(1)所述的超声波发射模块发射一个单周期超声波,所述的处理器在间隔ΔT时间后,将所述的超声波接收模块输出信号转换为数字采样信号f(n)；(2)比较出采样信号f(n)的最大值f<Sub>max</Sub>,采样序号为n<Sub>max</Sub>；(3)从f(n<Sub>max</Sub>)向f(1)搜索第一个过零点,采样序号为n<Sub>cross</Sub>；(4)计算杂波信号和∑f=<Image he="168" wi="231" file="926296DEST_PATH_IMAGE002.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>；(5)如果杂波信号和∑f>K,则判断为草地；否则,则判断为非草地。(The invention discloses a grassland identification method based on clutter analysis, which comprises a moving platform capable of moving autonomously, wherein a processor is arranged in the moving platform, an ultrasonic transmitting module and an ultrasonic receiving module are arranged at the bottom of the moving platform, a grassland identification algorithm is arranged in the processor to confirm whether the position of the moving platform is grassland or not, and the grassland identification algorithm comprises the following steps: (1) the ultrasonic transmitting module transmits a single-period ultrasonic wave, and the processor converts the output signal of the ultrasonic receiving module into a digital sampling signal f (n) after the interval delta T; (2) comparing the maximum value f of the sampled signals f (n) max Sampling number n max (ii) a (3) From f (n) max ) Searching f (1) for the first zero crossing point with the sampling sequence number n cross Calculating clutter signal sum ∑ f = Sum of spurious signals ∑ f>K, judging the lawn; otherwise, judging the lawn is not grassland.)

1. Grassland identification method based on clutter analysis, including the motion platform that can independently remove, the motion platform inside set up the treater, motion platform bottom installation ultrasonic emission module and ultrasonic receiving module, ultrasonic emission module set up ultrasonic emission probe and signal driver circuit, ultrasonic receiving module set up ultrasonic receiving probe and signal amplification circuit, signal driver circuit and signal amplification circuit connect the treater, its characterized in that: the processor is internally provided with a grassland recognition algorithm to confirm whether the position of the motion platform is grassland or not, and the grassland recognition algorithm comprises the following steps:

(1) the processor transmits a single-period ultrasonic wave through the ultrasonic wave transmitting module at regular intervals T, and converts the output signal of the ultrasonic wave receiving module into a digital sampling signal f (n) after the ultrasonic wave signal is transmitted at an interval delta T, wherein n =1,2,3, and the sampling time interval is delta T; when the sampling times reach N, ending the sampling process, wherein delta T is the time interval from signal emission to signal sampling, and delta T is the time interval between two AD samplings;

(2) comparing the maximum value f of the digital signal f (n)_maxSampling number n_max；

(3) From f (n)_max) Searching f (1) for the first zero crossing point with the sampling sequence number n_cross；

(4) Computing clutter signal sum ∑ f =；

(5) If the clutter signal sum sigma f is larger than K, judging the grassland; otherwise, judging the lawn to be non-grassy, wherein K is an empirical threshold.

Technical Field

The patent relates to a grassland identification method based on clutter analysis, belonging to the technical field of mobile robots.

Background

The mowing robot can normally work in a set working area only if the mowing robot has grassland recognition capability. The grassland is characterized in that green grasses grow on common land, the grasses are various in types, and the leaves are short and wide, and have dense coefficients. Currently, there are two main ways to detect grass. One is a method of identifying color characteristics. The image sensor collects ground images, color information of the images is analyzed by adopting an image processing algorithm, and green is used as an identification characteristic. But this method does not address the effect of changes in lighting conditions on imaging quality. The other is to identify the conductive characteristics of the plant as a characteristic. The bottom of the mowing robot is provided with two electrodes to form a sensor, when the mowing robot is on a lawn, blades of the lawn can be connected with the two electrodes, and the mowing robot contains moisture and has certain conductivity, can influence the conductivity between the electrodes, and has obvious distinguishing characteristics relative to air. But this method fails to detect when the grass is sparse or too dry. Therefore, a reliable method for lawn recognition by the mowing robot needs to be explored.

Disclosure of Invention

In order to solve the problems, the patent provides a grassland identification method based on clutter analysis, which is characterized in that the grassland is identified by taking multiple reflections of ultrasonic waves from the grassland.

The technical scheme adopted by the patent for solving the technical problem is as follows:

grassland recognition method based on clutter analysis, including the motion platform that can independently remove, the motion platform inside set up the treater, motion platform bottom installation ultrasonic emission module and ultrasonic receiving module, ultrasonic emission module set up ultrasonic emission probe and signal driver circuit, ultrasonic receiving module set up ultrasonic receiving probe and signal amplification circuit, signal driver circuit and signal amplification circuit connect the treater, the inside grassland recognition algorithm that sets up of treater, confirm whether the motion platform place position be the grassland, grassland recognition algorithm include following step:

(1) the processor transmits a single-period ultrasonic wave through the ultrasonic wave transmitting module at regular intervals T, and converts the output signal of the ultrasonic wave receiving module into a digital sampling signal f (n) after the ultrasonic wave signal is transmitted at an interval delta T, wherein n =1,2,3, and the sampling time interval is delta T; when the sampling times reach N, ending the sampling process, wherein delta T is the time interval from signal emission to signal sampling, and delta T is the time interval between two AD samplings;

(2) comparing the maximum value f of the digital signal f (n)_maxSampling number n_max；

(3) From f (n)_max) Searching f (1) for the first zero crossing point with the sampling sequence number n_cross；

(4) Computing clutter signal sum ∑ f =；

(5) If the clutter signal sum sigma f is larger than K, judging the grassland; otherwise, judging the lawn to be non-grassy, wherein K is an empirical threshold.

The beneficial effect of this patent mainly shows: the sound wave reflection waveform is analyzed, the disordered and low-intensity reflected waves reflected by the plants are recognized, and the reflected waves are used as distinguishing characteristics of the lawn and the common ground to perform lawn recognition, non-contact detection is performed, and the reliability is high.

Drawings

FIG. 1 is a functional block diagram of an embodiment of the present patent;

FIG. 2 is a schematic representation of a ground reflection waveform;

figure 3 is a schematic representation of a grass reflection waveform.

Detailed Description

The invention is further described below with reference to the accompanying drawings:

referring to fig. 1-3, the grassland identification method based on clutter analysis comprises a moving platform capable of moving autonomously, wherein the moving platform can be provided with driving wheels and supporting wheels, and can realize execution, retreat and rotation of any angle. The motion platform inside set up treater 1, motion platform bottom installation ultrasonic emission module and ultrasonic receiving module, ultrasonic emission module set up ultrasonic emission probe 3 and signal drive circuit 2, ultrasonic receiving module set up ultrasonic receiving probe 5 and signal amplification circuit 4, signal drive circuit 2 and signal amplification circuit 4 connect treater 1. The processor 1 controls the ultrasonic transmitting probe 3 to transmit ultrasonic signals through the signal driving circuit 2, the ultrasonic signals are converted into electric signals by the ultrasonic receiving probe 5 after being reflected, and the electric signals are transmitted to the processor 1 through the signal amplifying circuit 4 to be subjected to AD sampling.

A grassland recognition algorithm is arranged in the processor 1 to determine whether the position of the motion platform is grassland or not, and the grassland recognition algorithm comprises the following steps:

(1) the processor 1 transmits a single-period ultrasonic wave through the ultrasonic wave transmitting module at regular intervals of time T, the processor 1 converts the output signal of the ultrasonic wave receiving module into a digital sampling signal f (n) after AD sampling at an interval of time delta T after the ultrasonic wave signal is transmitted, n =1,2,3, and the sampling time interval is delta T; when the sampling times reach N, ending the sampling process, wherein delta T is the time interval from signal emission to signal sampling, and delta T is the time interval between two AD samplings;

the processor 1 performs signal sampling after a time interval of Δ T, so as to avoid direct interference of the ultrasonic transmitting probe 3 to the ultrasonic receiving probe 5. The Δ T time may be set as a time required for the ultrasonic signal to travel from the ultrasonic transmission probe 3 to the ultrasonic reception probe 5. Meanwhile, N times of the sampling time interval Δ T should be smaller than the fixed time T, i.e., the sampling should be completed within the fixed time T.

(2) Comparing the maximum value f of the digital signal f (n)_maxSampling number n_max；

Maximum value f_maxThe vibration caused by the ultrasonic wave reflected by the ground at the ultrasonic receiving probe 5 is corresponded.

(3) From f (n)_max) Searching f (1) for the first zero crossing point with the sampling sequence number n_cross；

From f (n)_max) The first zero-crossing point in the f (1) direction is the end position of the oscillation of the ground-reflected ultrasonic wave caused by the ultrasonic receiving probe 5.

The method comprises the following steps: when f (i) is opposite to f (i-1), n_crossAnd = i is the zero-crossing position.

(4) Computing clutter signal sum ∑ f =；

Summing up sampling signals before oscillation signals generated by ground reflected ultrasonic waves to obtain echo signals before ground reflected waves arrive, wherein if the echo signals are common ground, no object capable of reflecting the ultrasonic waves exists between the ultrasonic wave transmitting probe 3 and the ground, so that the clutter signal sum sigma f is close to zero; on the contrary, in the case of grass, the ultrasonic receiving probe 5 has grass blades or grass stalks stacked one on another from the ground, so that the clutter signal sum Σ f has a certain amplitude and can be used as a feature signal for identifying grass.

(5) If the clutter signal sum sigma f is larger than K, judging the grassland; otherwise, judging the lawn to be non-grassy, wherein K is an empirical threshold.

And judging whether the current position is the grassland or not by taking the clutter signal and the sigma f as a judgment basis.