Development of Path Planning Algorithm for an Autonomous Mower Tractor

Path planning is an essential part for autonomous mower tractor to travel and mow. Objectives of the paper were to analyze operation patterns by a farmer, to extract and optimize waypoints, and to demonstrate generation of formatted planned path for autonomous mower tractors. An 18-kW mid-mower tractor was operated by a skilled farmer on grass fields. To measure tractor travel and operation characteristics, an RTK-GPS antenna with a 2-cm RMS error, an inertia motion sensing unit, a gyro compass, a wheel angle sensor, and a mower on/off sensor were mounted on the mower tractor, and all the data were collected at a 10-Hz rate. And all of sensor data were transferred through a program to show the status immediately on the notebook. From 3 grass field tests, total 53,412 data points (every 0.1s) were obtained, and amount the data 73% was straight steering, 22% was turning steering, and 5% was for others (e.g. artificial error, needless work). Field test data showed some overlap, especially in the turning areas. Based on the human operation patterns, path planning algorithm was suggested for autonomous mower tractor. Finally path generation was demonstrated in a formatted file and graphic display. Results of the study would be useful to implement and test autonomous mower tractor, but further research needs to be done to improve the performance.