Motion Simulation Of Fully Constrained Spatial 3 Dof Cable-driven Parallel Mechanism

In general,Cable-driven parallel mechanisms(CDPMs)are a special type of parallel mechanisms driven by cables as instead of rigid links.As a result of the unilateral driving property of cables,CDMs require redundant actuation to maintain positive cable tensions.As a kind of parallel robots,CDPMs have advantages in load capacity,stiffness,efficiency,and so on.Furthermore,CDPMs overcome the major weakness of rigid-link parallel robots: workspace.Unlike rigid links,cable lengths can vary in a wide range,which enlarges the workspace of CDPMs.This thesis focuses on the statics,kinematic,dynamic,force distribution,workspace,control and simulation analyses of CDPMs aiming to improve the inverse and forward kinematics,force distribution analysis,static positioning,feasible trajectory and workspace planning accuracies of CDPRs.To do so,four cables,3 DOF spatial type CDPM is considered.In almost all CDPR / CDPM research works the architectures of the mechanisms are arranged in such a way that all the cables are arranged to be attached to the platform at their either lower or upper side edges that is in order to let the platform to move freely covering large workspace.However,there are some field of applications which doesn't necessarily need the platform to be without a cable at the bottom or freely rotating,rather to be fixed at the bottom with one cable.So,in this thesis the CDPM considered has one cable which is placed at the bottom of the mechanism.Since forward kinematics of a CDPM is closed-loop structure,it is relatively difficult than that of inverse kinematics.In this thesis,Newton-Raphson numerical method which is modified to improve its computational aspect by establishing the mapping between the Newton-Raphson matrix and the Jacobian matrix is applied to obtain the forward displacement solutions.In order to assist this process,an algorithm is developed.Moreover,inverse kinematics,which is the length of the cables is computed for the given position of the platform of the three DOF spatial type CDPM.The other distinctive characteristic of CDPMs is the unilateral property of the cables,i.e.cables can only pull but not push.Therefore,CDPMs require redundant actuation to maintain positive tensions by the cables.It is important to ensure suitable tension conditions in CDPMs such that the pose of the moving platform can be fully restrained by at least one appropriate set of positive cable tensions.In this thesis,Force Closure,Null Space approach,and Dividing Workspace approach are used to obtain positive tension solution for CDPMs.Furthermore,dynamic analysis and control of the 3 DOF spatial CDPR are also covered in this research work.Cascade control scheme that has inner and outer loop is applied.The inner is used to control the position of the mechanism whereas the outer loop controls the tension.In addition,the codes,modeling and motion simulation of is done using Matlab,Simulink,Sim Mechanics,and Solidworks are used.