The Design Of The Autonomous Walking Obstacle Avoidance And Control System Of The Lawn Mower

In recent years,autonomous driving of unmanned vehicle technology is in a stage of rapid development,self-driving technology enables the car to autonomously drive on the highway.On the premise of ensuring safety,it's more convenient for people's life.With the continuous advancement of science and technology,autonomous walking equipment has gradually entered people's life.Therefore,this paper studies the design of autonomous walking obstacle avoidance and control system of lawn mower.With the improvement of people's living conditions,weeders have been widely used.However,in the garden or green space environment,there are also trees,swings,man-made landscapes of different materials and other facilities.The requirements for a lawn mower are not only to trim the lawn and avoid trees and rockeries,but also to pass through the facilities such as a swing(in a highly permissible situation).As much as possible,trim the lawn in the space that the lawn mower can pass.The existing autonomous weeding machine can not identify the artificial facilities such as grass,shrub,swing and so on.Therefore,some land may not be trimmed,trees may be cut,or even knives may be damaged.In this paper,the autonomous walking obstacle avoidance and control system is designed.In this system,the ultrasonic range location technology of ultrasonic phased array is used to avoid the object in front of the weeder.And then the wavelet pretreatment and Linear SVM learning algorithm are used to process the signals,so that the intelligent identification of the object is completed.This paper is based on STM32F103 as the core controller to complete the transmission,echo reception and processing analysis of ultrasonic signals.After that,the wavelet preprocessing which performed for the echo signal is to obtain the amplitude frequency characteristics of the signals.Through separating the components of high-frequency energy and low-frequency energy from theamplitude-frequency characteristics,the high-frequency and low-frequency energy components can be used as signal characteristics.By using the Linear SVM algorithm,which belongs to a method of machine learning,to classify the signals of high frequency and low frequency components,so that it can distinguish whether the front object is a weed or a tree or other artificial facilities.At the same time,combined with the ultrasonic phased array technology,the system can achieve the purpose of autonomous walking and avoiding obstacles.From the premise of practicality,this paper introduces the working principle,hardware circuit design,software implementation and debugging test of the whole automatic walking obstacle avoidance and control system in detail.This paper will be elaborated from the following sections:In the first part,the introduction of this paper mainly introduces the research significance and purpose,summarizes the current development status of the application of self-propelled walking obstacle avoidance system at home and abroad,meanwhile,analyzes the advantages and disadvantages of the currently used technology and inherits the advantages to improve shortcomings,which makes the research has a clear direction.In the second part,this paper introduces the basic principle of ultrasonic phased array technology,especially introduces the working principle of "single-shot and multi-receive" phased array model.Compared with the "multi-shot and single-receive" phased array model of traditional method,the advantages and disadvantages of both methods are demonstrated,and finally we introduce the application of "single-shot and multi-receive" phased array model in detail.In the third part,the paper mainly introduces the basic concept of wavelet transform which involves the concept of continuous wavelet transform and discrete wavelet transform,eventually we expound the function of wavelet transform in signal analysis.In the fourth part,the principle and hardware circuit design of the autonomous walking obstacle avoidance and control system are mainly introduced.The design mainly includes MCU module,the design of the ultrasonic phased array,ultrasonic transmission circuit,signal amplification circuit,ADC module conversion and the upper computer part.This paper mainly focuses on signal amplification and conditioning circuit,which ismainly used to amplify,detect and filter the echo signals.In addition,we expound the design and operation process of the whole hardware circuit,the typical circuit and usage of each core chip,and analyze the function of each core chip in the whole circuit.In the fifth part,this paper introduces the software design,debugging,and summary of the system,which includes the introduction of software development platform,embedded programming of STM32F103 core processor,wavelet preprocessing and Linear SVM algorithm.In addition,the debugging is carried out for the entire automatic walking obstacle avoidance and control system,and the debugging results and error analysis were carried out on the system.At the end of the paper,I summed up the scientific research work during my postgraduate period.Meanwhile,I put forward the improvement and the prospect of the next work for the autonomous walking obstacle avoidance system of the lawn mower.