| China is the world's major producer and consumer of fruits,which has prompted the growing area of orchards in our country to increase year by year.According to statistics,in 2015,the planting area of orchards in our country increased by 6.1%over the same period of last year.The intensity of weeding work in the orchards is also increasing.At present while the area is increasing,the orchard in our country mainly uses artificial weeding,which is not only inefficient but also labor-intensive.Aiming at the existing problems in the orchard weeding process,the paper is based on the existing platform,designs a forward obstacle avoidance mechanism to realize the detection of obstacle while mowing the grass,and controls the position and attitude of the vehicle through the fuzzy control system bypass obstacles and return to the original mowing path in order to achieve automatic avoidance of mowing the local area.The research work done in this paper is as follows:1)Firstly,based on the existing platform,the dissertation designs the mechanical barrier obstacle avoidance mechanism of the mowing robot from three aspects:structure rationality,sensor arrangement and practicability of the actual processing.The final designed mowing robot mainly consists of the body,a bracket seat,a fixing frame and a detection mechanism.The detection mechanism mainly consists of an arc-shaped arm fixing fork and an arc-shaped arm,where in nine groups of contact devices are uniformly distributed on the arc-shaped arm for detecting the obstacle of front,the arc-shaped arm with a length of 1000mm,Extending 400mm,horizontal center 200mm from the ground.2)The modeling and analysis of the movement of the mowing robot in the process of moving forward are carried out to verify the rationality of the forward obstacle avoidance mechanism in the course of using,doing dynamics analysis of the body,the curved arm and obstacle collision.Through the analysis of its movement,draw the conclusion of feasibility in actual use;The control system performance experiment was designed to verify the feasibility of the self-built control system and the best driving speed when the vehicle body was moving forward.The average net productivity and the cutting height were taken as the evaluation index of mowing quality and effect,the average driving speed is 0.25~0.30m/s,the average net productivity is 0.17~0.22m~2/s and the cutting height is 16.98~19.85cm.Through the motor PWM value,the average driving speed and the average net productivity of the relationship between the three drawn control system performance is good.3)According to the research requirements of this paper,fuzzy control system is designed and simulated.Because the research of this paper is the way of the car body moving forward at a constant speed,this dissertation takes the angle deviation and the rate change of the angle deviation as the input and the change of the directional angle as the output.By detecting the obstacle in the front 100°range,determination of the relationship between the object position and posture.Through the smooth simulation output surface,the performance of the fuzzy control system designed in this paper is verified,at the same time,the curve of the relationship shows that the output steering angle of the vehicle body is very small within the range of 0~20°deviation,the body output steering angle is also increasing with increase,when the angle deviation and its rate of change close to the maximum,the basic body to maintain 50°maximum steering angle.4)Design of the arc-arm effect verification and return accuracy test,draw the arc-arm return error of about 2.0~4.1°;According to different obstacle avoidance strategies,safety distance test and heading keeping test were carried out.Experiments show that after the obstacle in contact with the vehicle back to the safe distance of 100cm,after heading 50°steering recovery 5s best.At this point,in the horizontal distance minimum,mowing efficiency and without obstacles with the premise of mechanical interference to achieve obstacle avoidance. |
PDF Full Text Request