| In recent years,the development of animal husbandry in China has been increasing year by year.Pennisetum sinese Roxb has many biological characteristics,including fastgrowing,high yield,high nutritional value,strong resistance and adaptability,etc.,which make its application degree deepening and create certain economic benefits.The southwest hilly area has humid air and abundant precipitation,which is suitable for the growth of Pennisetum hydridum.However,due to the steep slope and rough roads in hilly and mountainous areas,the harvester has higher requirements for obstacle crossing performance.At the same time,due to the complex field environment,it is difficult to ensure that the stubble height is consistent and it is easy to cause the cutter to stall because of the uneven feeding amount,which requires a higher driving level for the driver.Therefore,it is of great significance to develop intelligent harvesting equipment for bamboo and grass in hilly areas to promote intelligent agricultural mechanization and improve the yield of bamboo and grass in hilly areas.Based on the investigation and research of related technologies and devices at home and abroad,this paper studies and designs the obstacle crossing system,header height automatic control system,and selfpropelled speed control anti-blocking knife system of an intelligent harvester in hilly and mountainous areas,which improves the driving ability and intelligent mechanization level of the harvester in hilly and mountainous areas,reduces the labor intensity of drivers,and improves the safety and reliability of the harvester in a complex field environment.This paper’s main contribution is as follows:(1)Through the analysis of the research status at home and abroad and combined with the actual situation,aiming at the problems of the existing Pennisetum harvest machine in hilly and mountainous areas,the key objectives,research contents and scheme design,model establishment,and simulation calculation of the obstacle crossing system,header height control system,and self-propelled speed control anti-blocking knife system of the harvester are determined,respectively.Finally,an intelligent harvester is designed for Pennisetum harvesting in hilly and mountainous areas.(2)In order to improve the field trafficability of the harvester in hilly and mountainous areas,a detailed comparative analysis of different chassis was carried out,and the inverted ladder crawler chassis with better trafficability was selected.The main components of the harvester,such as the header,the silo,and the engine,are selected,and the size is determined.The three-dimensional model of the whole machine is established.By calculating the lateral and longitudinal stability of the whole machine on the ramp,the maximum ramp angle is determined.Finally,the prototype is assembled and debugged to ensure that its components,such as the crawler chassis walking,the lifting function of the cutting table,the normal operation of the cutter,and the self-unloading function of the silo,work properly.(3)Firstly,after investigating different types of profiling mechanisms,three different profiling mechanisms are designed for three different displacement sensors for comparative analysis,and the rod displacement sensor with the highest reliability is selected as the header height detection device.The control of the height of the control lever adopts a crank slider mechanism,which has a simple structure and can realize fine control of the control lever.Because the working environment of the harvester is very complex and the driver needs fine operation,this paper designs an automatic disengagement mechanism.In the event of an emergency,the driver can take emergency measures to disengage the actuator and the joystick to ensure driving safety.The start-up test was carried out to determine the parameters in the control program so that the height of the header can be controlled within the range of 15-20 cm.The height detection mechanism,the actuator,and the automatic release mechanism can meet the design requirements through the start-up test,and the height control system of the header can control the lifting of the header on the undulating road surface to ensure that the height of the header is always within 15-20 cm,which meets the design requirements.(4)Different types of speed sensors are tested and analyzed.Finally,a more secure and stable inductive speed sensor is selected,and the bracket is designed and installed.The pulse signal can be output in real time after testing.The control of the speed joystick is driven by a rack and pinion mechanism.The mechanism has a simple structure and can achieve fine control of the joystick.Because the working environment of the harvester is very complex and the driver needs fine operation,this paper designs an emergency parking system.In the event of an accident,the driver can open the parking switch to stop the vehicle immediately to ensure driving safety.A start-up test was carried out to determine the parameters in the control program.Through the start-up test,the feeding amount detection mechanism,the actuator,the automatic disengagement mechanism,and the emergency parking system can meet the design requirements.The speed control system of the harvester can continuously adjust the speed according to the change in cutter speed,ensure maximum harvesting efficiency,prevent the cutter from stalling,and meet the design requirements.(5)This field experiment was carried out in a bamboo grass planting base in Liming Village,Fengdu County,Chongqing City.The obstacle crossing function,header height automatic control function and speed automatic control function of the harvester were mainly tested.The test results show that the prototype can successfully cross the trench with a width of 400 mm and the obstacle with a vertical height difference of 300 mm,and can climb the slope with a slope of 40 %(21.8 °).In the automatic height control test,the height data of each point of the prototype cutting table is in the range of 15 cm ～ 20 cm,and the vertical height difference is 4.2 cm,which meets the design requirements.The standard deviation of the stubble height data after harvesting is calculated,and the result is 1.5 cm,which meets the requirement of stubble height.The prototype harvests at the maximum throttle to form a blockage at the feed inlet.The time from the beginning of harvest to the blockage of the feed inlet is measured to be 4 minutes and 8 seconds,and the distance is 63.6 meters.Open the speed control anti-blocking system,in the same way to harvest,there is no phenomenon of inlet blockage,to meet the requirements of automatic anti-blocking function. |
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