Study of H_* Control for 4WD Tractor-Implement Systems

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The objective of this research work is the robust controller design for tractor-implement system. The research work is divided into four categories (1) Formulation of mathematical model of tractor-implement system (TIS) under field operation condition including internal rotating parts of the system. (2) A field experiment with a tractor-implement system tinier tillage operation and its analysis, (3) A parameter identifiction laboratory test with the tractor-implement system, and (4) Robust controller design analysis with the tractor-implement systeim.(1) Dynamical characteristics of the tractor-implement system under tillage operationsGenerally a tractor-implement system works in heavy-duty conditions under tillage operations. We executed the field experiments for tillage operations with the tractor-impliment system under various conditions. Analyzing these data, we formulated a mathematical model for the TIS under field operating conditions. The model includes both internal rotational … More and translational motions and represents the feedback control characteristics of the system.(2) Parameter identification of the tractcr-implement systemFor the clarification of the TIS overall behaviors, the knowledge of two parameters is inevitable. We then execute the parameter identification test. One of the parameter is a pair of time constant that represents the torque-fuel relationship and dynamics of the system. The other is the viscous coefficient of the engine-transmission system. A nonlinear RSM method was introduced to identify these parameters.(3) Robust controller design analysis with the tractor-implement systemTalking account of the nonlinearity of the tractor-implement system(TIS), we propose a controller design method which consists of H_*00 robust control. As the tractor-implement system under tillage operation is heavily influenced by the torque disturbances, the stability of tire speed control is essentially important in tillage operations. First, we applied the Mixed-Sensitivity approach of the robust control system for the TIS and obtained the set of H_* controller Second, we designed the feedback control of the TIS using the proposed H_* controller instead of the mechanical govemor. The dynamic characteristics of the TIS are greatly improved. Less