Browsing by Author "Tatum, Ralph P."

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    Compensation strategies for robotic motion errors for additive manufacturing (AM)
    (University of Texas, 2016-08-10) Bandari, Yashwanth K.; Charrett, Thomas O. H.; Michel, Florent; Ding, Jialuo; Williams, Stewart W.; Tatum, Ralph P.
    It is desirable to utilise a robotic approach in additive manufacturing as Computer Numerical Control (CNC) is expensive and it has high maintenance costs. A robotic approach is relatively inexpensive compared to CNC and can provide much more flexibility, enabling a variety of configurations and easier parallel processing. However, robots struggle to achieve high positioning accuracy and are more prone to disturbances from the process forces. This paper attempts to characterise the robot position and velocity errors, which depend on the build strategy deployed, using a laser speckle correlation sensor to measure the robotic motion. An assessment has been done as to whether these errors would cause any problem in additive manufacturing techniques, where the test parts were built using the Wire+Arc Additive Manufacture (WAAM) technique. Finally, different compensation strategies are discussed to counter the robotic errors and a reduction of 3 mm in top surface profile irregularity by varying the wire feed speed (WFS) during the path has been demonstrated.
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    Laser speckle velocimetry for robot manufacturing
    (SPIE, 2017-06-26) Charrett, Thomas O. H.; Bandari, Yashwanth K.; Michel, Florent; Ding, Jialuo; Williams, Stewart W.; Tatum, Ralph P.
    A non-contact speckle correlation sensor for the measurement of robotic tool speed is presented for use in robotic manufacturing and is capable of measuring the in-plane relative velocities between a robot end-effector and the workpiece or other surface. The sensor performance was assessed in the laboratory with the sensor accuracies found to be better than 0:01 mm/s over a 70 mm/s velocity range. Finally an example of the sensors application to robotic manufacturing is presented where the sensor was applied to tool speed measurement for path planning in the wire and arc additive manufacturing process using a KUKA KR150 L110/2 industrial robot.