Chee Meng Chew

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Automatic welding of tubular TKY joints is an important and challenging task for the marine and offshore industry. In this paper, a framework for tubular joint detection and motion planning is proposed. The pose of the real tubular joint is detected using RGB-D sensors, which is used to obtain a real-to-virtual mapping for positioning the workpiece in a(More)
This paper presents a novel approach employing nonlinear control for stabilization of standing posture for a humanoid robot using only hip joint. The robot is modeled as an acrobot where model parameters are estimated through adaptive algorithm. A `non-collocated partial feedback' controller is applied. This is integrated with a linear feedback control,(More)
This article presents a novel utilization of the concept of entropy in information theory to a model-free reconstruction of 3D space in presence of noise. We show that its formulation attains its global minimum at the upper edge of this space to facilitate the extraction of its volume. Furthermore, we present a Monte Carlo approach that is based on the(More)
Welding joints for offshore oil rigs present a complicated geometry and require multiple passes. This paper introduces a complete collision-free offline path planning approach for such joints. Collision detection is performed using A* search on a three dimensional grid, where triangular mesh representations of the welding joint and its fixture form the(More)
We present an adaptive sampling approach to 3D reconstruction of the welding joint using the point cloud that is generated by a laser sensor. We start with a randomized strategy to approximate the surface of the volume of interest through selection of a number of pivotal candidates. Furthermore, we introduce three proposal distributions over the(More)
An automated bead layout methodology is proposed for multi-pass welding on varying seam angle. This methodology will replace the tedious process of `teaching and playback' in the current line of robotic welding. To develop the proposed method, manual flux cored arc welding has been conducted on several workpieces. It is then ascertained that the bead size(More)
In this paper, an adaptive sampling algorithm is proposed for reconstruction of a complex weld geometry based on the obtained 3D point cloud. Several pivotal samples for reconstructing the weld geometry are selected from the point cloud using a randomized strategy in the initial stage of the iterative algorithm. Based on the pivotal samples, the model is(More)
We present a deep learning approach to estimation of the bead parameters in welding tasks. Our model is based on a four-hidden-layer neural network architecture. More specifically, the first three hidden layers of this architecture utilize Sigmoid function to produce their respective intermediate outputs. On the other hand, the last hidden layer uses a(More)