This paper develops a new wavelet-based visual tracking system for miniature aerial vehicle (MAV) system. The visual signals for visual tracking system is formulated based on using wavelet coefficients. The design uses multiresolution interaction matrix with half and details image to relate the time-variation of wavelet coefficients with the velocity of the MAV and controller. The design is evaluated on a quadrotor MAV system to demonstrate the effectiveness of the wavelet based 6-DOF visual tracking system without using image processing unit. The evaluation results show that the MWT based linear controller can provide accuracy and efficiency without using image processing unit provided that the system does not contain any uncertainty.

This paper presents a method for maintaining high accuracy of laser-guided robotic manipulation by continuously compensating for position and alignment errors for aerospace manufacturing processes. The objectives of the method are to use the robot to perform reconfiguration in a flexible fixture and minimize the calibration work (tool, workpiece), continuously track the position and alignment of the mounted tool on the robotic arm, and minimize the positioning and alignment errors between the tool and the workpiece. The proposed method basically estimates first the transformation matrix between the 6 Degrees-of-Freedom (DoF) reflector sensor, which is mounted on the robotic arm with respect to robotic flange, and second the transformation matrix between the laser tracker frame with respect to the robot base frame. For estimating the two matrices, two solvers based on an iterative absolute orientation method and hybrid optimization solver are presented and thoroughly discussed. The calibration method is first validated in a robotic simulation environment to visualize the transformations before (initial guess) and after (final solution) calibration. The results show that the two calibration solvers are able to detect the exact poses (ground truth) from a simulated data set. Second, the method is applied to a laser assisted robotic system which is composed of Leica Absolute Tracker AT960 and the reflector Leica Tracker-Machine Control (T-Mac) as well as a 6 DoF KUKA KR 60 robotic arm. The method is used to successfully register the laser measurements with respect to the robot base frame.

In this paper, we investigate consensus based distributed robust adaptive tracking control strategy for second-order nonlinear multi-agent systems. The design only uses the states of the neighboring agents with directed communication topology in the presence of uncertainty. Robust and adaptive control algorithms are used for each agent to deal with uncertainty associated with leader input and follower agent dynamics. Lyapunov, Graph and sliding mode control theory uses to show that the proposed distributed cooperative design can reach an agreement with follower agents and track the states of the leader asymptotically. Analysis shows that robust consensus algorithm can force the states of the followers to track the sliding surface and remain there. In contrast with existing distributed design, the proposed consensus controller does not require the bound of the dynamical uncertainty and leader input for the follower agents. Evaluation results are presented to show the effectiveness of the proposed design for real-time application.

In this paper, a multiple circular contours extraction method is applied to estimate the geometric primitives of multiple circles in the three-dimensional space for robot-assisted industrial automation for manufacturing processes. The primary objective is to establish an accurate reference frame which is a major requirement in the robot-assisted riveting process for floating aircraft fasteners used in aerospace structures assembly. The reference frame that constitutes the positions, the diameters, and orientations of the fastening holes is used to minimize the positioning and alignment errors between the floating fasteners and the workpiece. The method can be divided into the following steps. Firstly, a Maximum Likelihood Estimation Sample Consensus (MLESAC) method is used to fit the plane on the point cloud and to classify the data into inliers (coplanar points) and outliers (noisy points due to strong reflections of laser on shiny metallic surfaces). Secondly, after downsampling the inliers, the data are rotated using the Rodrigues formula such that the normal direction of the estimated plane and the z-axis direction are parallel. Thirdly, the Delaunay triangulation is constructed on the rotated inliers and a confidence interval is estimated to classify the points that are located at the circular boundaries of the holes from the inliers. Fourthly, a hierarchical clustering approach is applied to partition the classified point cloud into three data sets belonging to one major hole and two minor holes. Finally, the convex hull is constructed on the clustered data sets and three circular profiles are fitted. The method is applied on a noisy experimental data and the repeatability of the outputs is discussed thoroughly. In our evaluation, the point cloud is acquired by a laser stripe sensor placed on a liner rail, which is attached on an end effector of a 6 Degrees-of-Freedom (DoF) KUKA robotic arm. The method is used to successfully automate the riveting of the fastener components on an aerospace structure.

Virtual Reality (VR) systems are of growing importance to aid decision support in the context of the digital factory, especially factory layout planning. While current solutions either focus on virtual walkthroughs or the visualization of more abstract information, a solution that provides both, does currently not exist. To close this gap, we present a holistic VR application, called Factory Layout Planning Assistant (flapAssist). It is meant to serve as a platform for planning the layout of factories, while also providing a wide range of analysis features. By being scalable from desktops to CAVEs and providing a link to a central integration platform, flapAssist integrates well in established factory planning workflows.