Study On Position/Force Control Scheme For Rheonomically Constrained Manipulators

With the development of the robotics, the application in each field of the robotics is more extensive. In most industry yield, for enhancing work efficiency and making the most of time and energy sources, cooperative method is used. For example, most assembling, work pieces machining, etc, are operated on dynamic platform, which means work pieces are handled on moving assembling line instead of on static platform. So the manipulators should adaptive this dynamic constrained initiatively to do the task accurately. When transiting the flexible big parts such as large-scale armor plates, considering the deformation and environment noise, all these require that the manipulator must do compliance movement for the contact force, and guarantee the work pieces being safe when they are moved. The research on the manipulators that constrained by rheonomically environment in this paper can solve the problem proposed above. The work efficiency and safety, precision will be enhanced.The result of research for position/force control for constrained manipulators can derive the effective algorithm for compliance control. The problem of the manipulators used on the time-variant constraint is resolved. It's significative for enhancing the safety, precision for work piece operation, and movement for work piece transition, also enlarging the application of robotics in industry! The work of this dissertation is combined with"Study on system dynamics and control of manipulators cooperating a flexible payload", which is supported by China National Natural Science. Based on system dynamics modeling, reducing order dynamics and wavelet network, this dissertation mainly research on position/force control algorithm for rhronomically constrained manipulators.The dissertation first established the dynamic model of manipulator; three characteristics of the model are discussed; the relationship between the contact force and Lagrange multiplier was educed. Choosing the independent coordinates to reduce the order of dynamics, a new model that only contains independent coordinates and Lagrange multiplier was derived. Based on the nominal model, a position/force controller was designed based on computed torque method. The system's stability under this controller was labored combined with Barbalat lemma. Then the principle and characteristics both of wavelet theory and NN theory are recommended, the combine methods of these two theories were introduced, a continuous wavelet network which will be used in this paper was educed, the structure and expression of this network were analyzed. To overcome the controller that based on computed torque method depending on the precision of the model and lack of robust, based on the model of reduced order dynamics, a robust position/force controller was designed based on wavelet network, the stability of the system was proved. The controllers educed in this dissertation can control the system to desired value both in position and force through theory analysis.Simulations were done and the chattering phenomena caused of sign function were solved. The results have confirmed the effectiveness of the controllers.