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Abstract-To facilitate scene understanding and robot navigation in a modern urban area, we design a multilayer feature graph (MFG) based on two views from an on-board camera. The nodes of an MFG are features such as scale invariant feature transformation (SIFT) feature points, line segments, lines, and planes while edges of the MFG represent different geometric relationships such as adjacency, parallelism, collinearity, and coplanarity. MFG also connects the features in two views and the corresponding 3D coordinate system. Building on SIFT feature points and line segments, MFG is constructed using feature fusion which incrementally, iteratively, and extensively verifies the aforementioned geometric relationships using random sample consensus (RANSAC) framework. Physical experiments show that MFG can be successfully constructed in urban area and the construction method is demonstrated to be very robust in identifying feature correspondence.I. INTRODUCTION When a mobile robot travels in a modern urban environment, the robot often needs visual signals from its onboard camera to assist navigation. A typical modern urban environment is usually rectilinear and consists of many structured objects and distinctive features such as vertical walls, parallel edges, orthogonal planes, etc. Extracting such features from video frames to form a quick scene understanding can directly benefit navigation tasks such as localization, mapping, obstacle avoidance, and motion planning.Here we design a multilayer feature graph (MFG) to facilitate the scene understanding in urban area. Nodes of an MFG are features such as scale invariant feature transformation (SIFT) feature points, line segments, lines, and planes while edges of the MFG represent different geometric relationships such as adjacency, parallelism, collinearity, and coplanarity. MFG also connects the features in two views and the corresponding 3D world coordinate system. Fig. 1 illustrates the MFG in the 3D world coordinate system. We design an MFG construction method using a feature fusion process which incrementally, iteratively, and extensively verifies the aforementioned geometric relationships using random sample consensus (RANSAC) framework.We have implemented MFG construction algorithm and tested it in physical experiments. Results show that MFG can be successfully constructed from raw image data. Since the process utilizes multiple types of geometric relationships,

Disabilities after neural injury, such as stroke, bring tremendous burden to patients, families and society. Besides the conventional constrained-induced training with a paretic arm, bilateral rehabilitation training involves both the ipsilateral and contralateral sides of the neural injury, fitting well with the fact that both arms are needed in common activities of daily living (ADLs), and can promote good functional recovery. In this work, the fusion of a gesture sensor and a haptic sensor with force feedback capabilities has enabled a bilateral rehabilitation training therapy. The Leap Motion gesture sensor detects the motion of the healthy hand, and the omega.7 device can detect and assist the paretic hand, according to the designed cooperative task paradigm, as much as needed, with active force feedback to accomplish the manipulation task. A virtual scenario has been built up, and the motion and force data facilitate instantaneous visual and audio feedback, as well as further analysis of the functional capabilities of the patient. This task-oriented bimanual training paradigm recruits the sensory, motor and cognitive aspects of the patient into one loop, encourages the active involvement of the patients into rehabilitation training, strengthens the cooperation of both the healthy and impaired hands, challenges the dexterous manipulation capability of the paretic hand, suits easy of use at home or centralized institutions and, thus, promises effective potentials for rehabilitation training.

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To realize ideal force/torque source in applications such as monopod hopping robots and assistive robots, force/torque controlled series elastic actuators(SEA) are widely used components. Most of existing SEA force/torque control approaches are based on the simple SEA whose force/torque output is proportional to the position of the motor with respect to the payload, however the structure of SEAs is becoming more and more complex, which leads to a nonlinear trend in SEA models. To overcome the problem, we propose a general control method, which is not restricted by the SEA mechanical structure, to control SEA output torque based on nonlinear disturbance observer(NDOB). Specifically, the presented strategy yields the first control solution, with guaranteed theoretical analysis, to successfully address the nonlinear SEA torque control problem, with simultaneous payload angular velocity identification as an additional benefit. The tracking performance of the designed control system is theoretically ensured by Lyapunov analysis. Furthermore, taking a nonlinear SEA for instance, simulation and experimental results suggest the effectiveness and superior performance of the proposed method by comparing it with existing method.

To improve and validate the performance of humanoid robot, the research on a table-tennis game by both humanoid robots is supported by 863, the national hi-tech program. Due to the limitation of the visual feedback system and the motion ability of the humanoid robot, a precise model of the table-tennis game is necessary to predict the ball's trajectory. This paper details the dynamic model of the ball's flight trajectory as well as its parameters calibration by Photron Fastcam, a high speed camera with 2kfps to capture the trajectory of ball. With the model's characteristics, ball's flight trajectory prediction based on a few observation points is employed as well as its noise sources are discussed. According to the requirement of table-tennis game by humanoid robot, a novel nonlinear observer is developed to improve the prediction accuracy. Finally, Experiments results with binocular vision show that the model and trajectory prediction proposed by the paper outperform the requirement of the game.