Kinematic and dynamic analyses, and, control of a new, very high precision parallel robot for use in micro and free-form machining

This thesis work consists of modeling and control of a parallel robot which is to be employed for free-forming and micro machining with its high-precision positioning capabilities. This parallel robot, or as called Yeditepe Parallel Robot (YPR), was designed in the context of TUBITAK funded project, filed as 105M213 and named as ?Free-form and micro-machining with the aid of parallel robot that is able to do precise positioning?. YPR is a 6 DoF robot and it was designed differently from common examples of the parallel robots, a 6-6 Stewart Platforms, as it has a 3-3 design which means both base and moving platform have three connections. The motion is created with linear slider pairs at the base and transferred to a moving platform via spherical and revolute joints at each leg connection. Control of YPR was realized with a PD controller along with a feedforward mechanism, employed to decrease control effort and get better positioning results. Control performance was checked with all possible configurations of feedback and feedforward loops by using two reference paths and tuned control parameters. Introducing gravity and cutting force disturbance were also inspected by means of positioning performance and the control scheme?s disturbance rejection capabilities. As a result, satisfactory positioning performance was achieved by employing both feedback and feedforward control loops.