KABLOYLA ÇALIŞAN PARALEL ROBOTLAR İÇİN ROTA OLUŞTURMA YÖNTEMLERİ

Abstract

The aim of this thesis is to implement CNC-based trajectory generation techniques with Cable Driven Parallel Robots (CDPRs). CDPRs are a special type of parallel robots that use motors and cables to manipulate an end-effector in space. Cable robots are becoming popular due to several advantages they have over traditional manipulators such as their large workspace and lightweight actuators. For the cable robots to perform properly there are a number of parameters that need to be studied. These include maintaining positive cable tension, cable elasticity, trajectory generation, controller design, and structural optimization. The scope of this thesis is limited to planar cable robots, where a four-cable robot has been chosen for the analysis. The reason for choosing a four-cable robot is that the fourth actuator offers a redundancy which allows control of the end effector with 3 DOFs while also being able to maintain tension. Maintain positive tension is very important as unlike traditional manipulators, CDPRs are not able to push against the end-effector, only pull. A positive tension algorithm ensures that none of the cables ever go slack. Cable elasticity and its incorporation into the mathematical model of the cable robot is another important part of the developed model. Trajectory generation is one of the most important topics in this research as it uses CNC-based trajectory generation algorithms to generate trajectories for a cable robot. These algorithms range from simple linear or circular interpolation to complicated 5th order splines which ensure continuity up to at least the second derivative. A combination of splines, and simple segments are used to generate standard and custom shapes and non-uniform data supplied by the user is also simulated by connecting splines with the data. These trajectories are tested in different scenarios and for different conditions such as changing speed or some non-zero angle reference for the end-effector. The controller design is another important aspect. It is a cascade controller which is very common for controlling motors. The controller gains are determined based on the settling time and the maximum overshoot. Lastly the structural optimization of the cable robot for dexterity, stiffness, and workspace is studied where the optimized robot was found to provide better results. A GUI is developed which incorporates all the different codes to make an easy-to-use tool for designing and simulating a cable robot.