Department of Mechanical engineering
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Item Vibration suppression of flexible beams for robotic assembly using vision and wrist motion(ACM Digital Library, 2023-11) Rout, Bijay KumarIndustrial robots are used in assembly operations to increase the productivity of the manufacturing process. In this operation, a robot grasp either a rigid or flexible object like beams, wires and sheets that may encounter undesired vibration in this object due to high speed motion of the robot. The present work designs a high-level control strategy using a robot vision system to suppress the vibrations of the flexible beams during the assembly process. The robot vision approach is used to detect the beam held by the gripper of the robot and measure the dimensions keeping an account of the change in perspective. The free response of the flexible beam is used for system identification regardless of dimension and material properties. To suppress the vibration of the flexible beam actively, the proposed high-level controller uses the wrist motion of the robot. The efficacy of the proposed approach is demonstrated by implementing it on a commercially available ABB 1410 industrial robot without modifying its controller for the beam-in-slot assembly operation. The proposed controller can suppress vibration amplitude up to 97.83% within 2.36 s and reduce suppression time by 96.23% compared to the control to no control scenarioItem Vision based control strategy to suppress residual vibration of flexible beams for robotic assembly using wrist motion(Sage, 2023-12) Rout, Bijay KumarAutomated assembly tasks require industrial robots to improve the efficiency of the manufacturing process. Most rigid or flexible objects handled by robots vibrate due to motion and transient disturbance. This work proposes an active vision-based vibration suppression strategy for flexible beams by providing motion to the wrist of a robot during robotic assembly process, which reduces the time to suppress vibration. The proposed method uses a cheap monocular camera to identify objects through a virtual marker and measure their dimensions. Subsequently, finite element method based mathematical model of a flexible beam predicts the maximum error. The proposed second stage controller determines the controller input in terms of wrist motion based on the predicted maximum error. The performance of the controller is assessed through simulations and experiments on metallic beams with different material characteristics and dimensions. The controller suppresses vibration amplitude within a safe limit so that object is inserted into the slot. It was observed from experiments that the controller can reduce vibration amplitude by ~96% in less than 2 s and decrease suppression time up to ~97%. These improvements were achieved without disturbing the internal robot controller.Item Robot vision-based control strategy to suppress residual vibration of a flexible beam for assembly(Emerald, 2023-04) Rout, Bijay Kumar; Marathe, AmolIndustrial robots are extensively used in the robotic assembly of rigid objects, whereas the assembly of flexible objects using the same robot becomes cumbersome and challenging due to transient disturbance. The transient disturbance causes vibration in the flexible object during robotic manipulation and assembly. This is an important problem as the quick suppression of undesired vibrations reduces the cycle time and increases the efficiency of the assembly process. Thus, this study aims to propose a contactless robot vision-based real-time active vibration suppression approach to handle such a scenario.Item Vibration Suppression of Non-Deformable Metal Strip for Robot Assisted Assembly Operation(IEEE, 2020-06) Rout, Bijay KumarCurrent work presents a vibration suppression strategies of a Non-Deformable Metal Strip which is induced by rapid action of an industrial robot. In this case an external controller is designed as outer controller without any interruption in the robot internal controller to suppress the residual vibration in NDMS. The proposed controller is simulated in MATLAB/Simulink environment and designed in Python IDLE to validate the controller. The external controller is a closed-loop feedback Proportional Integral Derivative (PID) controller designed especially for an industrial robot that does not have control over acceleration. The robustness of the proposed controller is tested experimentally through the vibration control of a NDMS which is supposed to perform peg in hole assembly operation in various operating conditions. The designed controller suppresses vibration in less than 5 seconds and the stability time is reduced by 95% for in a Peg-in-hole assembly task.Item Vision sensor based residual vibration suppression strategy of non-deformable object for robot-assisted assembly operation with gripper flexibility(Emerald, 2022-06) Rout, Bijay Kumar; Marathe, AmolIndustrial robots are extensively deployed to perform repetitive and simple tasks at high speed to reduce production time and improve productivity. In most cases, a compliant gripper is used for assembly tasks such as peg-in-hole assembly. A compliant mechanism in the gripper introduces flexibility that may cause oscillation in the grasped object. Such a flexible gripper–object system can be considered as an under-actuated object held by the gripper and the oscillations can be attributed to transient disturbance of the robot itself. The commercially available robots do not have a control mechanism to reduce such induced vibration. Thus, this paper aims to propose a contactless vision-based approach for vibration suppression which uses a predictive vibrational amplitude error-based second-stage controller.