Four Position Synthesis And Kinematics Simulation Analysis Of Spherical Six-bar Mechanism Based On Solution Region Synthesis Theory

With the development of bionic technology,robot technology and space technology,spherical mechanism has been widely used in practical life.Compared with the spherical fourbar mechanism,the spherical six-bar mechanism can achieve more complex trajectory curve and kinematics requirements,and achieve higher precision transmission while keeping the advantages of simple and low pair mechanism.However,because of more design parameters of spherical six-bar mechanism,it is difficult for designers to identify circuit defects and tedious performance analysis process,so it is difficult to achieve efficient and practical design.On the basis of the research at home and abroad,this paper extends the solution domain synthesis theory and method of planar six-bar mechanism to solve the position synthesis problem of spherical six-bar mechanism,and realizes the efficient synthesis design of spherical six-bar mechanism.The main research contents are as follows:(1)In this paper,a method of synthesizing spherical RR bar based on the four-position parameter information of a spherical moving rigid body is presented.Firstly,the spherical coordinates are introduced to define the position and pose of the moving rigid body,and then the synthesis equation of spherical RR bar is derived according to the invariable condition of the length of the bar,and the curve expressed according to the equation is called spherical Brinell solution curve.The synthesis of spherical RR bars can be completed by reading the parameters of points on the solution curve with a certain step size.By classifying the points on the solution curve,the method of constructing the solution domain of spherical six-bar mechanism is given.(2)The solution domain synthesis theory and method are applied to solve the four-position synthesis problem of spherical six-bar mechanism.When the spherical 3R open chain fourposition parameter information is given,two spherical RR members are added to the spherical3 R open chain comprehensively according to the given parameter information to obtain the spherical six-bar mechanism with one degree of freedom.According to the different ways of adding RR member,seven types of spherical six-bar mechanism can be obtained.Aiming at four spherical six-bar mechanisms of seven types,a symbol discrimination method for loop defects was proposed based on the bar group splitting method.By using this method,the mechanism solutions of spherical six-bar mechanisms with loop defects in the solution domain were eliminated,which ensured that the mechanism solutions in the solution domain had practical value and reduced the blindness of designers in choosing.(3)By using D-H parameter method,spatial geometry principle,spherical trigonometry and bar group splitting method,the position analysis equations of spherical six-bar mechanism were established,and the position analysis of Stephenson-IIIA spherical six-bar mechanism was carried out among the above four spherical six-bar mechanisms.The simulation model of Stephenson-IIIA spherical six-bar mechanism was established by parametric modeling method,and its position simulation analysis was carried out to verify the correctness of position analysis of numerical example.The kinematics analysis of Stephenson-IIIa spherical six-bar mechanism was carried out on the basis of the verification of the simulation results and the theoretical calculation results.The input and output angular velocity and angular acceleration of Stephenson-IIIa spherical six-bar mechanism were obtained with the change of time,and the stability of the mechanism was analyzed in the process of motion.