Integrated vibration and visual sensing for a vision-based end-effector control of a flexible robotic manipulator

Flexible lightweight robotic manipulators have a number of advantages over traditionally bulky industrial manipulators. Yet a considerable number of robotic manipulators still lack of feedback control to achieve a satisfactory operating performance in dynamic and unstructured environments. The use of vision-based end-effector provides the required sensing for feedback control to achieve an accurate object positioning. However, the manipulator's motion can cause significant structural vibrations which are detrimental to the quality of the vision-based sensing. In addition, vision-based control techniques generally face constraints for real-time control due to rather low calculation speed to process camera images. The present paper aims to propose a method that integrates the vibration and visual information for a vision-based end-effector control so to obtain more stable images for accurate object positioning. The flexible robotic manipulator model is developed based on a non-linear dynamic model utilizing the co-rotational finite element method incorporated with smart piezoelectric actuators/sensors. This modelling method uses multiple co-ordinate (co-rotational) systems which rotates and translates with each element, so that the geometric non-linearity present in rotating manipulator system can be dealt with efficiently. To improve the accuracy of end-effector positioning, the vibration sensing and control method will be used to stabilize the visual information obtained from the vision-based end-effector. Simulation results and an initial experiment demonstrate the feasibility of the proposed sensing and control method to enhance the positioning accuracy of a flexible manipulator.