Addis Ababa Institute of Technology

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Browsing Addis Ababa Institute of Technology by Subject "3-DOF Delta Robot"

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    Passivity-Based Control of Delta Robot for Trajectory tracking
    (Addis Ababa University, 2021-11) Meron, Tesfaye; Dereje, Shiferaw (PhD)
    Parallel manipulators have some special properties in comparison to serial robots, making them increasingly appealing in industrial applications as technology advances. such as: more rigid structure, high orientation accuracy, better control on the limits of velocities and accelerations, good positioning accuracy, high payloadto- weight-ratio and low inertia of moving parts. On the other hand, parallel robots are nonlinear multi-input multi-output (MIMO) systems whose dynamics are governed by a highly nonlinear coupled, time-varying system with many uncertainties such as load variation, friction and external disturbances, making robot control more di cult and necessitating a robust control system. This thesis provides passivity-based control as one of the strategies for designing robust controllers for a 3-DOF Delta Robot trajectory tracking. Passivity is a fundamental attribute of many physical systems that may be nearly characterized in terms of energy dissipation and transformation and its intrinsic input output property quanti es and de nes a system’s energy balance when external inputs imitate to produce some outputs. Furthermore, it is a method of operating a system with the goal of making the closed loop system passive. The 3-D model of a 3-DOF Delta robot is designed in 3D-CAD (Solidworks). Hence, this modeling environment enables to introduce real but not approximated parameters of the robot and eased computation of large matrixes. Dynamical model with all the kinematic constraints for a robot will simply be found by exporting a 3D-CAD model of the robot to Simscape Multibody. The kinematics, dynamics and singularity analysis of the 3-DOF Delta robot has been carried out, a passivity based controller has been designed and its performance is tested by tracking a circular trajectory centered at (15,15,/0) on X-Y plane with 160mm radius. The simulation result shows that the steady state tracking is reached in about 3 seconds for a circular trajectory and X & Y rms error of 2.88mm.The robustness of the designed controller is illustrated mathematically and the simulation is carried out on MATLAB, and it shows that the controller is robust to external disturbances.