| Sugarcane was the most important sugar raw material in China,and the planting area was the third in the world.In China,the sugarcane harvest was dominated by manpower and the labor productivity was low.In the 2017-2018 season,the mechanization rate was only 1.4%,which was very urgent for sugarcane harvesting machinery.Guangxi and Yunnan were the two largest sugarcane producing areas in China.The sugarcane fields were mainly hilly and mountainous.It was necessary to research the stability of sugarcane harvesters in hilly areas because of the risk of turning over in the sugarcane harvesters.In this paper was based on the research of our team’s four-and two-track type sugarcane combine harvester.Based on the basic theory of vehicle chassis and vehicle stability theory,combined with virtual prototyping technology,and stability of four-and two-track type sugarcane combine harvester was researched theoretically and experimentally.Two kinds of harvester’s operation index of optimal driving stability were determined.It was provided the key technical support for the structure design and improvement of sugarcane harvester and it had important basic research significance.The main research contents and conclusions were as follows:(1)Static stability analysis of four-and two-track type sugarcane combine harvester.With the static stability theory,and evaluation of static stability by limiting roll Angle.The structure model of two harvesters was established by using Recur Dyn software and its static stability was simulated.The simulation values of the ultimate roll Angle of four-crawler vertical uphill,vertical downhill and transverse slope were 32~o,37~o and 16~orespectively.The theoretical values were respectively:32.5~o,37.9~oand 16.0~o.When the horizontal rotation Angle of the conveyor arm was the initial position(0~o)and the simulation values of the limit rollover Angle of the vertical slope,vertical slope and transverse slope were 24~o,43~o and 21~o,respectively.The theoretical values were 24.8~o,43.9~o and 21.1~o,respectively.At the limit position(60~o),the simulation values were 17~o,48~oand 15~o,respectively.The theoretical values were 17.1~o,48.1~o and 15.3~o,respectively.The results show that the error between the simulation result and the theoretical calculation of the ultimate turning Angle of the harvester was within 10%,indicating that the simulation and theoretical calculation can reflect the static stability of the two harvesters.When the horizontal rotation Angle of two-tracked conveyor arm was the initial position(0~o),the stability of the longitudinal slope and the transverse slope were 13.6%and 24.1%worse than that of the four-tracked conveyor arm,and the stability of the vertical slope and the transverse slope are 21.2%and 4.3%better than that of the limit position(60~o).(2)Comparative analysis of limit speed theory of two harvesters.Through the theoretical calculation of two harvesters flat and ramp 15~o to limit the speed,are:4.07 km/h,3.96 km/h(four tracked harvester);2.37 km/h,1.81 km/h(two tracked harvester delivery arm horizontal rotation Angle of the initial position 0~o);2.06 km/h,1.52 km/h(two tracked harvester conveying arm level 60~o rotation Angle for the limit position).The results of theoretical calculation and experiment show that the two harvesters will not roll over when driving in high or low gear on flat ground.Four tracked harvester in 15~o slope to running at high and low gear is not going to happen,two tracked harvester in 15~o slope to running at high gear will happen,so when ramp to two tracked harvester should be running at low gear.(3)Comparison of steering stability of two harvesters in laterite and red loam road conditions.Two harvesters used Recur Dyn software for steering stability simulation,and analyzed the steering stability of laterite and red loam road conditions.It is concluded that the yaw velocity of four-track harvester in two road conditions was 0.3 rad/s,but the yaw velocity in red loam road condition fluctuates greatly.The yaw velocity of laterite and red loam road with two-track harvesters respectively were 0.35 rad/s and 0.25 rad/s.The results showed that the steering stability of four-track harvester was 14.2%better than that two-track harvester,and 16.6%worse than that two-track harvester.(4)Comparative test of dynamic stability of two harvesters.The dynamic pitch Angle and roll Angle of two harvesters were measured by using the Recur Dyn software simulation and the flight position sensor test.By comparing the low speed and high speed driving of the two harvesters,it was concluded that the standard variance of the pitch Angle and the roll Angle of the two-track harvester were larger than that the four-track harvester:0.42,0.57,4.97,6.35.Through the stability test of horizontal rotation Angle of the conveyor arm measured in practice,the maximum side Angle of horizontal rotation Angle of the conveyor arm from the initial position 0~o to the ultimate position 60~o was-1.3~o to-8.4~o.The results showed that four-track was better than two-track at both speeds.With the increase of horizontal rotation Angle,the stability of the harvester becomed worse.(5)Simulation analysis of the influence of external forces on the stability of the whole machine.The stability cone mathematical model was established,and the stability margin was used to evaluate the stability of the whole machine,the stability margin was simulated by MATLAB.Simulation results showed that under the same external interference,the stability margin of four-track harvester was larger than that of two-track harvester,that was,the stability of four-track harvester was better than that two-track harvester.Two-track harvester conveying arm rotation Angle from the initial position 0~o to limit position60~oof side tumbling stability margin limit value are:27~o-15.5~o,That was,with the increase of the horizontal rotation angle of the conveyor arm,the vehicle’s stability was worse. |
