Design And Kinematical Analysis Of A Novel3-CRPu Pure Translational Parallel Robot

Lower-mobility parallel robots (PRs) not only have the main merits of6degreesof freedom (DOFs) parallel robots, such as high stiffness, high accuracy, high load-to-weight radio, low inertia and high speed, but also have other advantages in terms ofuncomplicated architecture, simple kinematical solutions, lower manufacting cost andeasy control. Therefore, the lower-mobility PRs have been become one of the researchfocuses in the fields of mechanisms and robots. Among which3-DOFs translationalparallel mechanism has been paid more and more attentions.In this dissertation, a novel3-CRPu pure translational parallel robotic mechanismwith3-DOFs is presented, which consists of a moving platform connected to a fixedbase by three identical kinematical limbs. Each limb is composed of a cylindric pair, arevolute pair and a parallelogram structure which consists of two revolute pairs andtwo spherical pairs. The axes of the cylindric pairs and the revolute pairs within thesame kinematical limb are parallel to each other.Mobility of the mechanism is analyzed and calculated based on the theory ofscrew. The rotational DOFs and the translational DOFs of three cylindric pairs areselected as the actuated joints of the mechanism, respectively. The forward and theinverse kinematical problems about position, velocity and acceleration are performedwith respcet to the differnet inputs. The workspace, singularity and dexterity areinvestigated as well. When the linear displacements of the cylindric pairs are selectedas the actuated inputs, the Jacobian is a3×3identical matrix. Therefore, the parallelmechanism has the same kinematical and dynamic performaces along differentdirections, which means the mechanism shows full-isotropic in this case. Based on thekinematical analysis, three linear displacements the cylindric pairs are selected as theactuated joints input. Dimensional synthesis of this parallel robot is also completedbased on the given workspace. Virtual prototype design of the3-CRPu parallel robot is realized by use of theTop-Down method of the Pro/E software and the generalized modular design method.The forward and the inverse kinematical simulations of the virtual prototype arecarried out. The simulation results verify the correctness of the theoretical analysisabout this mechanism. The physical prototype of3-CRPu pure translational parallelrobot is set up according to the theoretical analysis and the virtual prototype analysis.Control system of the prototype is designed preliminarily based on the opennumerical control system model of “PC and motion controller”.