| The level of agricultural mechanization is being improved, and coverage rate of agricultural mechanization is being promoted rapidly in our country, on the condition that issues of agriculture, farmer and rural area are being concerned increasingly by government of China. Additionally the policy of fiscal subsidies for agricultural implements is playing an active role. Achievement attracting worldwide attention has been procured in the fields of facilities farming, however, Chinese facilities farming level is still falling behind recently compared to mechanization of agricultural implements for planting in the open air. Therefore, it is urgent to develop mechanical equipment for conservatory work, in respect that productive activity of facilities farming still relies on labor intensive and burdensome in China nowadays.A kind of flexible chassis was designed on the basis of 4WD and 4WS utilizing electric wheels, which were installed on biasing shafts, to develop chain drive for modern facilities farming satisfying the demand that a kind of dexterous motion vehicle's chassis for conservatory work vehicles. Motion model of six degree of freedom was established, in addition, equations of states were built in the light of different forms of motion. Simulation software was utilized to simulate the process of motion to analyze the effect of parameters of motion from steering angle. The result of simulation manifested that the motion model of flexible chassis enabled to reflect its motion properties.In addition, design for driving system and control strategy is carried out, besides, machine elements and electronic device of flexible chassis are introduced in dissertation. Structure design for monowheel driving system is fulfilled on the basis of function, and then strategy design is carried out according to monowheel driving system. Moreover, BLDCM working principle and control method are analyzed in detail. Integral control strategy of flexible chassis is furnished, and controller working principle is offered concretely at last.What's more, central controller is designed in accordance with motion performance of flexible chassis. The model of master chip is chose and all parts of hardware circuits have been designed for central controller, besides, circuit boards have also been made. Where after, software system devising and programming are carried out for central controller and then sensor and speed signal is acquired and control command is sent by computer. The design for control controller is preliminarily achieved.Finally, test sample vehicle for flexible chassis is made, on the basis of design from every part and research foundation, utilizing BLDCM as elementary unit. A series of mechanical and technical problems are solved during the course making sample vehicle, furthermore, some motion performances of it are being tested initially. Central control system is evaluated to analyze the problems and disadvantages in process of practice, in order to lay a strong theory foundation for its amelioration and optimization, so that precision, reliability and responsiveness of control system of central controller is improved, as well as motion stability and mechanical performance of flexible chassis are upgraded.In summary, it is feasible for flexible chassis to be actualized, basing on motion model and central controller design for flexible chassis, as well as sample vehicle which has been made in this dissertation. Moreover, this dissertation also provides theoretical basis and test means for delving into motion properties and control strategy of flexible chassis. |
