Study On Road Feeling Of Teleoperated Agricultural Vehicles

When agricultural vehicles work in the field,their working environment is relatively harsh and complicated.Drivers who drive the vehicle for a long time are not only easy to fatigue but also cause the quality of work to decrease,and accidents may even occur.Teleoperation systems can realize remote control and solve this problem well.However,the remote-operated driver is far away from the vehicle and knows little about the road information,which is not conducive to the driver’s judgment of the road.Therefore,the simulation of the road feeling of the vehicle had attracted the attention of domestic and foreign scholars.This paper takes a Mao Yuan MY250 tractor with a teleoperation system as the experimental platform.Based on the teleoperation system,a set of road feeling test and simulation system is designed.Firstly,the overall scheme of road feeling design for teleoperation agricultural vehicles is proposed,and then the mechanism of road feeling is analyzed,and the method of road feeling design is determined.Then the software and hardware design of the road feeling test and simulation system is completed.Finally,the road feeling test and simulation of teleoperation agricultural vehicles on different roads were completed.The main contents and work were as follows:1.Determine the overall design scheme.According to the structure of the teleoperation system which was built before and the requirements of road feeling design,the overall design scheme was determined.The design of road feeling mainly includes two parts: road feeling test and road feeling simulation.The road feeling test was completed by the torque sensor installed on the steering wheel,and the road feeling simulation was completed by the Logitech G29 steering wheel.2.Road feeling design strategy.Based on the analysis of the generation mechanism of vehicle’s road feeling,the target torque required for road feeling design was calculated,and then by comparing different road feeling design methods and influencing factors,the most suitable design scheme for teleoperated agricultural vehicles road feeling was determined.3.Software and hardware design of road feeling test for the teleoperated tractor.To test the road feeling of the vehicle,the original steering system needs to be modified.The models of torque sensor were determined by the transformation principles and basic parameters,and the Raspberry Pi was used as the main control board of the system to complete the design of the on-board control system including the switch control module,AD acquisition module and RS485 communication module.The software design mainly included the design of the serial communication protocol,the design of the main program of Raspberry Pi,and the development of a real-time data reading interface of road feeling.The formulation of the serial communication protocol function code was introduced in detail.The main program was designed in C language and compiled by a serial debugger.The user interface was developed by Labview to realize the real-time reading of road feeling data.4.Design of road feeling simulation system.The road feeling simulation system mainly included the interactive design of man-machine interface and Logitech steering control device.The input of steering command was realized by the Logitech G29 steering control device,which was also used as a road feeling simulation device.Firstly,the human-computer interaction interface of the steering control device was designed,then the data of the steering device was read and calibrated,and then the function of the buttons of the control device was formulated to complete the road feeling simulation of the teleoperated agricultural vehicles.5.Road feeling tests and simulation of the tractor.Finally,according to the road feel test system,the steering resistance torque of teleoperated tractor was measured on the grass and cement roads at different speeds,and the simulation test of road feel was carried out on the grass and cement roads by using the Logitech steering wheel.The test results show that the steering torque of teleoperated tractor on different roads varied greatly,but the overall trend was the same.At first,the steering torque increased with the increase of the angle,and it began to fall when the steering wheel angle is between 100°and 120°and rises slightly when the steering wheel angle is about 200°.The road feel of teleoperation tractor was simulated by the G29 steering wheel of Logitech,and the goals of evaluation indexes were between 6 and 9 points,which showed that the simulated road feel satisfied the driver.