Study On Integrated Design And Application Of Variable Constraint And Self-adaptive Structure Of Machinery

As long as the development of modern manufacture and technology, to improve the kinematics, kinetics capability and level of intelligentization of mechanical system; the mechanical structure has self-adjustment and self-adaptability according to various interior and exterior uncertainty are becoming hotspots of mechanism scholars'investigation.Self-adaptive structure of mechanism is a mechanical structure that mechanism can automatically adapt to exterior working conditions, objects, and parameters but need not test or control. The mechanism with such structure is called self-adaptive mechanism. The self-adaptive mechanism usually has structure characteristics of multi-degree of freedom, variable structure and variable freedom. Because the quantity of the original driving member is smaller than that of the mechanical freedom, it is usually a typical underactuation mechanism system. And, the self-adaptive structure is a mechanism structure based on variable constraints. It utilize the characteristics of the variable constraint which is able to be enforced, released, adapted and controlled, and makes the structure can be self-adapted to the exterior varieties.The self-adaptive mechanism is recently widely applied in practice. However, the lack of systematic research on its commonness working mechanism and theories and methods of integrative design, the lack of a specific definition and classification are badly restricting its application, development and innovation. Based on such demand, this thesis has deeply and systematic analysis and research on variable constraint and self-adaptive mechanism structure.The major tasks of this thesis are as follows:①Based on the particular analysis of the relationship between movable join and constraint character, according to the general constraint and view of design and application, the thesis here advances the classifications of: the motion constraint and dynamical constraint; interior constraint and exterior constraint; basic constraint and extra-constraint; ordinary constraint and variable constraint. And characteristics of different constraints are analyzed. And for the first time, the variable constraint is classified to variable motion constraint; variable geometry constraint; Force closed constraint and dynamical constraint. Diversified constraint equations of variable constraint are listed; factors of variable, adjustable and controllable of the variable constraint structure are indicated; and functions and scopes of appliance of the variable constraint are specified. A foundation to analysis and design of self-adaptive mechanism structure settled.②Based on the research about the self-adjustable mechanism structure, according to deep analysis of foregone self-adaptive mechanism, a concept is advanced here: the self-adaptive mechanism is that device which can automatically adapt to the change of exterior working conditions, objects, and parameters depends on the self-adjustment and realize the adapt to varieties, and dependably achieve the expected working requirements, without any testing and controlling and special control structure either. By research on the self-adaptive mechanism working mechanism, here indicates that the"self-adaptive"in fact means its self-adaptability for varieties of the mechanism constraint and freedom. Its self-adaptive functions are realized based on variability and adaptability of varieties parameters of variable constraint power and energy, via constraint or release for degree of freedom to adjust the mechanism structure for realization.③According to the characteristics of function structure and objects to be adapted, two class methods of self-adaptive machines are advanced here. Mainly aimed at variable structure self-adaptive mechanism, variable freedom self-adaptive mechanism and internal-force-closed self-adaptive mechanism, the main structure characters and self-adaptive mechanism are set forth. According to their common characteristics, the main points of self-adaptive mechanism synthesis are particular discussed in the thesis and some basic principles and current methods of the synthesis designs of self-adaptive mechanism are brought forward also.④To the question of the demand in different structure of internal-force-closed self-adaptive mechanism, a new method of type synthesis of kinematical chains is finished systematically, that is Contracted Graph and Subchain Method. Based on which, a method to detect isomorphism of kinematical chains based on the All-Loop-Link-Join-Matrix is researched and innovated, and all possible independence structures of less than 10 links (10 links included) with 0 or–1 DOF are brought forward .Here in-depth analysis and research for the design, methods and principles of internal-force-closed self-adaptive structure is done, and the design process and general principles and methods is are brought forward. And by instances the process and methods of its function and structure design is discussed also.⑤In the thesis a conditional self-adaptive finger design method based on the apery finger of the single-degree of freedom arthrosis is forwarded. Firstly imitated the gesture of human fingers from unbend to make a fist, its single-degree mechanism is synthesised, and then add a conditional freedom in the original mechanism to advance and complete its self-adaptability. In the thesis, the method of structure synthesis; the variable constraint structure scheme of arthrosis; and how to obtain the conditional degree of freedom of 3-DOF underactuation finger mechanism are deeply discussed. And the kinetostatic analysis model having variable moment of underactuation finger is build up; the synthesis method according to parameter of optimization of fingers, and select three dimensions of the knuckle, take the best and medium condition of grasp of transmission angle to be the basic structure, take the three contact force to be equal as target of optimization is indicated. Fixed the parameter of optimization, the functions of optimization target is built up, and several conclusions for choice, throughing the Particle Swarm Optimization (PSO), are achieved. Via the simulation experiments of the dummy sample machine, the strong self-adaptive function of the finger mechanism is demonstrated.⑥Based on the analysis of the function structure of stopper from ChongQing Steel Co., Ltd., according to the main problems of its self-adaptive structure, the variable adaptive structure of two slotting-pin pair with spring force closed constraint to replace the original force closed Higher-pair structure of hammer—roller—wobbly pole are designed in the thesis. Tthe working stability and dependability of stopper are improved, and completes the self-adaptive function is completed also. The testing result from experiments of the dummy sample machine indicates that the design method of this thesis is correct, effective and dependable.The research achievements upon have very important theory significance and project actual value in enriching and developing the design theories and methods of modern mechanism structure; developing innovative design methods and field of self-adaptive machine; advancing the analysis and design level of self-adaptive machine structure of our country.