Automation and cybernetics: control of a flexible one-link manipulator

Introduction One of the most important requirements in robotics is accuracy, and in order to solve this problem robot structures are built very stiff and rigid. In addition, frequently most of today’s analyses and controls of industrial robots are based on the assumption that the robot arm is just a collection of rigid bodies, so that, in order to position the end effector to the commanded location, the joint angles must assume computed values, and the robot is presumed stiff enough so that the end effector will thus be in the intended location. Therefore, most robots are built to be massive and unwieldy. Nowadays, the use of light materials has increased in fields such as robotics, machine tools or advanced space applications, and with requirements such as large working volume, high mobility and the ability to carry heavy payloads, it is desirable to build a lightweight robot arm. Therefore, the rigid-bodyassumption in robotics has to be abandoned. Flexibility effects noticeably limit the performance of the different structural elements and thus must be taken into account both at the design and control level. Modelling and control activities should therefore be carried out together. The deflection and the vibration of the flexible arm robot present a severe problem to the accuracy and position stability. Even the static deflection of the robot arm has to be taken into account for positioning accuracy; and what is