Design And Development For Kinematics Analysis Software Of Symmetrical 3-DOF Parallel Mechanism

Symmetrical 3-dof parallel mechanism has attracted much attention due to its simple structure,easy to control and isotropy.Based on D-H method in dual quaternion form,the kinematics model of parallel mechanism is established,and the kinematics analysis is carried out by polynomial algebra.Finally,these processes are programmed to develop software that can automatically analyze the kinematics of symmetrical 3-dof parallel mechanism.The software makes kinematics analysis more concise and efficient,reduces the workload of designers,and thus shortens the design cycle.The main research of this paper is as follows:A method for directly establishing kinematic constraint equation of parallel mechanism in polynomial form is proposed by using D-H method described by dual quaternion and half angle tangent method.The motion between linkages described by D-H method is expressed in the form of dual quaternions.Then,the parallel mechanism is divided into multiple closed-loop single chains.For each closed-loop single chain,the kinematic constraint equation of the parallel mechanism is established by D-H method based on dual quaternion.At last,the constraint equation is polynomialized by the method of half angle tangent,and the whole modeling process is simplified according to the result.Based on polynomial algebra,a general positive and negative solutions of position analysis method for symmetric 3-dof parallel mechanism is proposed,and the positive and negative solutions of velocity and positive and negative solutions of acceleration can be obtained by using the derivative method according to the analytical solutions obtained,and the singular configuration can be solved by using the jacobian matrix whose determinant is equal to zero.The above kinematics analysis methods are programmed by the computer algebra system Maple and MATLAB GUI,and an automatic kinematics analysis system for symmetrical 3-dof parallel mechanism is developed.By using this software,the positive and inverse solutions of position,velocity,acceleration and singular configuration can be obtained automatically by only inputting the geometric parameters of the mechanism and the constraints of the degree of freedom of the platform.Using automatic parallel mechanism kinematics analysis system of 3-CPR spatial parallel mechanism and 3-RPR planar parallel mechanism kinematics analysis,get these the closed-form positive and inverse solutions of position,velocity,acceleration as well as the singular configuration.These results are consistent with those obtained by ADAMS software simulation,proves the correctness and feasibility of the kinematics analysis system for symmetrical 3-dof parallel mechanism.