Design, simulation and control of a tendon-driven robot arm

This thesis presents a design for cable-driven serial manipulators with two degrees of freedom which is lightweight and safe to use in a non-industrial setting. Conventional industrial robot arms have several applications such as welding, palletization and on the assembly line, but are heavy to use, have large sizes and are not always safe for human operators in proximity. This thesis aims to explore the idea of a cable-driven serial manipulator, where a simple system of cables and pulleys transmits motion between the actuators and links. The model proposed here is a cable-driven robot arm which attempts to overcome the issues of conventional robots by placing all the actuators in a motor bank at the base of the robot body as opposed to positioning them at every joint along the arm, and by reducing the total number of actuators in the model. An experimental model constructed using 3D printed parts forms the basis of digital models built using the Simscape Multibody toolbox. The design explored here is based on a microgravity environment. Initially, physical models of the DC motors are used in the Simscape models, which are later represented using transfer functions. PID controllers control these motors, and the required parameters are obtained using the root locus method through calculations and MATLAB codes. The next step involves testing the Simscape model by recording its response to a step input. This is first done on two different single degree-of-freedom arms, followed by a 2 degree-of-freedom model. In order to limit fluctuations in voltage of the motors, a low-pass filter has been used in these models. Comparison with output plots from MATLAB calculations validate these results.M.S.Includes bibliographical reference