Fourier Descriptor Based Simulteneous Type And Dimensional Design Of 1-DOF Assistive Sit-to-stand Mechanism

As an interdisciplinary subject between robot and rehabilitation,rehabilitation robot has become a research hotspot in the field of robotics and mechanism because of its great social value in the future.Among them,the research of rehabilitation standing robot aiming at the rehabilitation standing process belongs to one of the important directions.The existing robots for the sit-to-stand rehabilitation are mainly multi-degree-of-freedom machines,which are difficult to control and costly,and therefor not easy to be propularized and promoted;however,the single-degree-of-freedom mechanism can be used to solve this problem well.The problem of tracing the standing motion is actually motion generation problem in the mechanism.Type synthesis is the selection of link number,the type of kinematic pairs and interconnection pattern of links.And dimensional synthesis is the determination of dimensional parameters of links.However,type and dimensional synthesis in the previous kinematic synthesis is mostly separated,which leads to the problem that resulting mechanism is not optional solution in terms of type and dimension simultaneously.And in the process of kinematic synthesis,the traditional theory only pays attention to the pure shape matching problem in the motion synthesis,but is hardly concerned with problem of time matching of trajectory.With this in mind,this thesis focuses on the sit-to-stand rehabilitation mechanism,based on the Fourier descriptor for the uniformity and non-uniformity in the time domain,and establishes a unified mathematics model for the coupled serial mechanism to achieve closedloop and open trajectory fitting.The model proposes an integrated design method that can simultaneously perform type synthesis and dimensional synthesis,and designs a new type of rehabilitation robot according to the theory.The main work and achievements of this thesis are listed as follows:1.Based on the Fourier transform theory,a general mathematical model for solving the closed-loop trajectory and open trajectory fitting problems is established by studying the coupled series mechanism.The research results show that the mathematical model can solve the problem of trajectory fitting,no matter whether the trajectory is closed or unclosed.2.Based on the Fourier descriptor,a type and dimensional integrated design method is proposed,and the common optimal solution of type and dimensional is obtained.3.The influence of trajectory fitting on the mechanism design under uniform and nonuniform time in Fourier transform is studied,and a unified mathematical model under uniform and non-uniform time series is constructed.4.Based on the above theory,a new type of rehabilitation robot is designed to verify the validity of the theory.