Position Control of a Parallel Mechanism Based Robotic Machining Bed

Modern technologies enable rapid removal rates to perform the desired tasks in order to achieve better finish in less time. However, this rapid removal rate greatly sacrifices the accuracy of the workpiece being machined. In recent years, researchers have tried to find solutions to tackle this issue so that accurate results can be obtained. A six degrees of freedom (DOFs) robotic machining bed is such a solution which is capable enough to mitigate the errors faced in conventional machining processes and attain desired accuracy. Despite its advantages this system too faces some errors, one of which stems from the positioning of the workpiece. The aim of this paper is to mitigate this error by incorporating a PID controller with a 6 DOF robotic machining bed. The research presents a mechanical design of the robotic bed as well as its kinematic model to determine the key parameters affecting its performance. Dynamic modelling of the bed has also been carried out to determine the dynamic effects of the positioning errors. To minimize these dislocation errors being faced by the robotic bed a classical PID controller has been integrated and its gains are tuned to achieve the desired positional accuracy. The proposed control strategy has been verified through both simulation and experimental results to prove the effectiveness of the system.