چكيده به لاتين
The primary objective of this thesis is a cable-driven parallel robot with moving platform and six cables, in which the load carrying end effector has three transitional and three rotational motions. Because of the nature of nonlinear dynamics, the inherent property of cables in pressure intolerance, the low mass of cables, and the possibility of large vibrations in this type of robot, checking, controlling and positioning accuracy of the end effector is more challenging than in serial robots. The nonlinear vibrations of the cables are one of the disrupting elements in decreasing the positioning accuracy of the end effector and the load bearing capacity since the dynamics of the end effector and the cables linked to it are interdependent. The Rayleigh-Ritz method is used in this thesis to analyze the non-linear vibrations of cables. The transverse vibrations of the cables are neglected since the mass of the end effector is significantly greater than the mass of the cables. First, the effect of the cable's longitudinal vibrations on the robot's kinematics will be examined. Then, the dynamic modeling of the mobile robot in three modes of rigid, non-linear vibrating, and linear vibrating cable will be investigated. Finally, it is also reviewed the effect of the non-linear vibration of cables on the transient and rotational positioning of the end effector and the movable base by numerical solution of the extracted dynamic equations. Two methods have been used in this thesis to validate the activities performed. In the first method, the routes of the robot's end effector and platform in the cases of rigid cable and non-linear vibrating cable are compared to the routes obtained from the robot's laboratory test. The modulus of elasticity of vibrating cables is assumed to be very large in the second method, and the routes of the effector and the platform are compared to the routes of the robot with rigid cables. The tracks in non-linear vibrating cable mode are compared with the results in linear vibrating cable mode in the final section. Finally, it is examined the advantages of reviewing non-linear vibrations over linear vibrations of cables.
