Design and control of a parallel robot with high payload capability

In this study examines the mechanical, kinematic, and hydraulic design of a parallel robot with high payload capacity, intended for operation in dusty and hot environments, such as foundries and forging factories. To protect the health of workers in such environments, a parallel arm mechanism was employed in the robot's design. The robot was developed with six degrees of freedom and enhanced mobility by sliding on a rail. A Denavit-Hartenberg (D-H) parameter table was prepared for the kinematic analysis of the robot, and both forward and inverse kinematic models of the system were developed, leveraging the advantages of the parallel arm mechanism. Additionally, the necessary trajectory and motion planning methods were integrated into the system to reach the designated end-effector positions. The mathematical model of the system was constructed, and simulations were conducted using the physical model in the MATLAB/Simulink environment. A PID controller was designed to ensure precise and rapid position control of the robot's joints. The parameters of this controller were optimized using the The Bee Algorithm (BA). Simulation results were analyzed to evaluate the system's performance based on criteria such as maximum overshoot (Mp), steady-state error (ess), total displacement, and total velocity change. The best performance improvement in terms of Mp was 57.84% in the elbow joint, while for ess, it was 4.93% in the carrier rail joint. In terms of displacement, the best performance improvement was 64.64% in the elbow joint, and for velocity change, it was 72.76% in the turret rotation joint. Trajectory tracking simulations conducted using the preliminary design and optimal parameters showed a 77.62% reduction in position error, decreasing the maximum error from 213.8 mm to 47.83 mm. The average position error was reduced by 37.40%, from 19.89 mm to 12.45 mm. Simulations using the optimized controllers provided torque-angular velocity and force-linear velocity graphs, which were used to select appropriate hydromotors and size the cylinders. Furthermore, hydraulic components such as the hydraulic pump, proportional directional control valve, hydraulic filtration components, and hydraulic oil tank were selected and sized. The selection and design of these hydraulic components were detailed. The workspace of the system was visualized and included in the thesis. In conclusion, the study demonstrated that the parallel robot with high payload capacity, using optimized controllers, could accurately follow the designated trajectory. The numerical values obtained from the study were presented in the form of graphs and tables.