Improvement of End-effector Orientability Capability in a Serial-parallel Cable Robot

In this paper, a hybrid model which consists of planar parallel robot with a 2-DOF arm is presented. This manipulator is based on cable parallel robots and a kinematic serial chain is utilized and added to a cable parallel chain. The hybrid manipulator can provide features of both serial and parallel mechanism. Understanding the orientability of the end-effector within this workspace gives a measure of the ability of the robot to perform manipulation tasks. Most underactuated parallel manipulators have a low rotational capability. To overcome it, this paper focuses its attention on a new family of serial-parallel manipulators. The initial goal of this design is to increase the orientability capability of a planar two-cable robot. The kinematic and dynamic analysis of this new type hybrid manipulator is presented. The dynamic modeling is performed by using a combination of Lagrange and Newton-Euler methods. This paper conducts the dynamic trajectory planning study to a novel design for the cable robots. In fact, time optimal trajectory planning is a strategy that is used to verify this new design. Two models are considered in the simulation part. A novel hybrid model is compared to a planar parallel cable robot. It is verified that the proposed design allows significantly reduced actuation energy and improved orientability capability compared to the parallel robot.