Mobile Formation Coordination and Tracking Control for Multiple Non-holonomic Vehicles

This paper addresses forward motion control for trajectory tracking and mobile formation coordination for a group of non-holonomic vehicles on SE(2). Firstly, by constructing an intermediate attitude variable which involves vehicles' position information and desired attitude, the translational and rotational control inputs are designed in two stages to solve the trajectory tracking problem. Secondly, the coordination relationships of relative positions and headings are explored thoroughly for a group of non-holonomic vehicles to maintain a mobile formation with rigid body motion constraints. We prove that, except for the cases of parallel formation and translational straight line formation, a mobile formation with strict rigid-body motion can be achieved if and only if the ratios of linear speed to angular speed for each individual vehicle are constants. Motion properties for mobile formation with weak rigid-body motion are also demonstrated. Thereafter, based on the proposed trajectory tracking approach, a distributed mobile formation control law is designed under a directed tree graph. The performance of the proposed controllers is validated by both numerical simulations and experiments

Egocentric Hand Detection Via Dynamic Region Growing

Egocentric videos, which mainly record the activities carried out by the users of the wearable cameras, have drawn much research attentions in recent years. Due to its lengthy content, a large number of ego-related applications have been developed to abstract the captured videos. As the users are accustomed to interacting with the target objects using their own hands while their hands usually appear within their visual fields during the interaction, an egocentric hand detection step is involved in tasks like gesture recognition, action recognition and social interaction understanding. In this work, we propose a dynamic region growing approach for hand region detection in egocentric videos, by jointly considering hand-related motion and egocentric cues. We first determine seed regions that most likely belong to the hand, by analyzing the motion patterns across successive frames. The hand regions can then be located by extending from the seed regions, according to the scores computed for the adjacent superpixels. These scores are derived from four egocentric cues: contrast, location, position consistency and appearance continuity. We discuss how to apply the proposed method in real-life scenarios, where multiple hands irregularly appear and disappear from the videos. Experimental results on public datasets show that the proposed method achieves superior performance compared with the state-of-the-art methods, especially in complicated scenarios

A Wireless System for Sport Assessment

In the context of sport assessment, the evaluation and monitoring of the referees decisions is of interest for several sports in order to avoid disputes and assist the referees in their activity. Some current solutions are based on video recording, third referee, etc. In this paper, a new wireless wearable system, result of the Italian research project REC-VISIO, is described suitable to assess the referees actions when they are on the move. The system is able to collect the referee staff visual perspective of a sport match, whose subjective is recorded, preprocessed and sent by a wireless network to a sideline workstation for final stabilization. The system architecture design and implementation are described along with the experimentation on the field, considering as use case a football match. The experimentation has shown the successful integration of all the different system components, where the cooperation of sensor-based subsystem, processing unit, and communication subsystem allows to collect and stabilize the video streaming reducing the effects of the movement of the referee, and send in real-time the video content to the sideline workstation without video quality degradation

HIL real-time simulation of a digital fractional order PI controller for time delay processes

Fractional order control has been used extensively in the last decade for controlling various types of processes. Several design approaches have been proposed so far, the closed loop performance results obtained being tested using different simulation conditions. The hardware-in-the-loop (HIL) real-time simulation offers a more reliable method for evaluating the closed loop performance of such controllers prior to their actual implementation on the real processes, such HIL simulation being highly suitable especially for complex, hazardous processes in which human and equipment errors should be avoided. The present paper proposes a hardware-in-the-loop real-time simulation setting for a digital fractional order PI controller in a Smith Predictor structure. The designed control strategy and fractional order controller is then tested under nominal and uncertain conditions, considering a time delay process