Vibration Based Control for Flexible Link Manipulator

Robotic manipulators are widely used to help in dangerous, monotonous, and tedious jobs. Most of the existing robotic manipulators are designed and built in a manner to maximize stiffness in an attempt to minimize the vibration of the end-effectors. This high stiffness is achieved by using heavy material and bulky design. Hence, the existing heavy rigid manipulators are shown to be inefficient in terms of power consumption or speed with respect to the operating payload. Also, the operation of high precision robots is severely limited by their dynamic deflection, which persists for a period of time after a move is completed. The settling time required for this residual vibration delays subsequent operations, thus conflicting with the demand of increased productivity. These conflicting requirements between high speed and high accuracy have rendered the robotic assembly task a challenging research problem. In addition, many industrial manipulators face the problem of arm vibrations during high-speed motion. In order to improve industrial productivity, it is required to reduce the weight of the arms and/or to increase their speed of operation. For these purposes, it is very desirable to build flexible robotic manipulators. Compared to the conventional heavy and bulky robots, flexible link manipulators have the potential advantage of lower cost, larger work volume, higher operational speed, greater payload-to-manipulator weight ratio, smaller actuators, lower energy consumption, better manoeuvrability, better transportability and safer operation due to reduced inertia. However, the major drawback of these robots is the inaccuracy of the end effectors due to low stiffness. Due to the importance and usefulness of these robots, researchers are nowadays engaged in the investigation of control of flexible manipulator. The issue of tip position control for flexible link manipulator has gained a lot of attention due to the great benefits, which can be achieved by changing the traditional rigid robots with flexible ones. Then, by measuring the elastic deformations of the link and using a more sophisticated control algorithm, the endpoint of the robot can be controlled with a relatively high degree of precision with minimal vibration. Using the vibration signal that is from the motion of the flexible links robot is one of the important methods used in controlling the tip position of the single-link arms. Compared with the common methods for controlling the base of the flexible arm the vibration feedback can improve the use of the flexible-link robot systems. 24