Showing papers presented at "International Conference on Control, Automation, Robotics and Vision in 2008"

Learning informative point classes for the acquisition of object model maps

Abstract: This paper proposes a set of methods for building informative and robust feature point representations, used for accurately labeling points in a 3D point cloud, based on the type of surface the point is lying on. The feature space comprises a multi-value histogram which characterizes the local geometry around a query point, is pose and sampling density invariant, and can cope well with noisy sensor data. We characterize 3D geometric primitives of interest and describe methods for obtaining discriminating features used in a machine learning algorithm. To validate our approach, we perform an in-depth analysis using different classifiers and show results with both synthetically generated datasets and real-world scans.

Stabilization of networked multi-input systems with channel resource allocation

Abstract: In this paper, we study the problem of state feedback stabilization of a linear time-invariant (LTI) discrete-time multi-input system with imperfect input channels. Each input channel is modeled in three different ways. First it is modeled as an ideal transmission system together with an additive norm bounded uncertainty, introducing a multiplicative uncertainty to the plant. Then it is modeled as an ideal transmission system together with a feedback norm bounded uncertainty, introducing a relative uncertainty to the plant. Finally it is modeled as an additive white Gaussian noise channel. For each of these models, we properly define the capacity of each channel whose sum yields the total capacity of all input channels. We aim at finding the least total channel capacity for stabilization. Different from the single-input case that is available in the literature and boils down to a typical H∞ or H2 optimal control problem, the multi-input case involves allocation of the total capacity among the input channels in addition to the design of the feedback controller. The overall process of channel resource allocation and the controller design can be considered as a case of channel-controller co-design which gives rise to modified nonconvex optimization problems. Surprisingly, the modified nonconvex optimization problems, though appear more complicated, can be solved analytically. The main results of this paper can be summarized into a universal theorem: The state feedback stabilization can be accomplished by the channel-controller co-design, if and only if the total input channel capacity is greater than the topological entropy of the open-loop system.

A fast Monte Carlo algorithm for collision probability estimation

Abstract: In order to navigate safely, it is important to detect and to react to a potentially dangerous situation. Such a situation can be underlined by a judicious use of the locations and the uncertainties of both the navigating vehicle and the obstacles. We propose to build an estimation of the collision probability from the environment perception with its probabilistic modelling. The probability of collision is computed from integrals of Gaussians and takes into account the uncertain configurations and the volume of both the vehicle and the obstacles.

Robot path planning in dynamic environments using a simulated annealing based approach

Abstract: This paper proposes a simulated annealing based approach to determine the optimal or near-optimal path quickly for a mobile robot in dynamic environments with static and dynamic obstacles. The approach uses vertices of the obstacles to define the search space. It processes off-line computation based on known static obstacles, and re-computes the route online if a moving obstacle is detected. The contributions of the work include the employment of the simulated annealing algorithm for robot path planning in dynamic environments, and the development of a new algorithm planner for enhancement of the efficiency of the path planning algorithm. The effectiveness of the proposed approach is demonstrated through simulations under typical dynamic environments and comparisons with existing methods.

Improving path planning and mapping based on stereo vision and lidar

Abstract: 2D laser range finders have been widely used in mobile robot navigation. However, their use is limited to simple environments containing objects of regular geometry and shapes. Stereo vision, instead, provides 3D structural data of complex objects. In this paper, measurements from a stereo vision camera system and a 2D laser range finder are fused to dynamically plan and navigate a mobile robot in cluttered and complex environments. A robust estimator is used to detect obstacles and ground plane in 3D world model in front of the robot based on disparity information from stereo vision system. Based on this 3D world model, 2D cost map is generated. A separate 2D cost map is also generated by 2D laser range finder. Then we use a grid-based occupancy map approach to fuse the complementary information provided by the 2D laser range finder and stereo vision system. Since the two sensors may detect different parts of an object, two different fusion strategies are addressed here. The final occupancy grid map is simultaneously used for obstacle avoidance and path planning. Experimental results obtained form a Point Grey's Bumblebee stereo camera and a SICK LDOEM laser range finder mounted on a Packbot robot are provided to demonstrate the effectiveness of the proposed lidar and stereo vision fusion strategy for mobile robot navigation.

A survey on topology control in wireless sensor networks

Abstract: Wireless sensor networks have a wide range of potential, practical and useful applications. However, there are many challenging problems that need to be addressed for efficient operation of wireless sensor networks in real applications. One of the fundamental and important problems in sensor networks is the topology control problem since most sensors are equipped with non-rechargeable batteries and the density of deployed sensors is very high. Topology control needs to reduce the power-consumption and extend the lifetime of sensor networks while satisfying certain application requirements. To energy-efficient control the topology structure of sensor networks, the common approaches are to adjust the transmission power of sensors and to dynamically schedule sensor's cycles. In this paper, we survey the state-of-the art topology control techniques, present an overview and analysis of the solutions proposed in recent research literature.

Effects of watermarking on iris recognition performance

Abstract: Protection of biometric data and templates is a crucial issue for the security of biometric systems, and biometric watermarking is introduced for this purpose. However, watermarking introduces extra information into the biometric data (biometric images or biometric feature templates) which leads to certain distortion. In addition, watermarked images are always subject to the risk of being attacked. Hence, whether and how biometric recognition performance will be affected by biometric watermarking deserves investigation. In this paper, we make a first attempt in such investigations by studying two application scenarios in the context of iris recognition, namely protection of iris templates by hiding them in cover images as watermarks (iris watermarks), and protection of iris images by watermarking them. Experimental results suggest that watermark embedding in iris images does not introduce detectable decreases on iris recognition performance whereas recognition performance drops significantly if iris watermarks suffer from severe attacks.

Observability analysis of SLAM using fisher information matrix

Abstract: This paper presents a new technique for evaluating the observability of the simultaneous localization and mapping (SLAM) problem. The state vector of an estimation theoretic formulation of the SLAM problem is recast to include all robot poses from which the measurements are made. This converts SLAM to a problem of estimating a set of unknown, constant random variables. Fisher Information Matrix of the resulting static estimation problem is derived and analyzed to examine the observability of SLAM. Outcomes of the analysis and comparisons to the observability analysis presented in recent literature are presented. Proposed technique makes it possible to analyze the observability of a range of SLAM problems with ease.

Stability of discrete-time iterative learning control with random data dropouts and delayed controlled signals in networked control systems

Abstract: This paper studies the robust stability of discrete-time iterative learning control (ILC) systems in a networked control system setting(NCS). First we consider the problem where data sent from a remote plant to the ILC algorithms is subject to random data dropouts. For this scenario we establish mean-square stability, taking into account the convergence of the covariance of the error along the iteration domain. Next, using this result, we derive a robust stability condition for a more general NCS-based ILC problem with data delays and dropouts in the control signals transmitted to the remote plant as well as data delays in output signals returned from the plant.

Trophallaxis in robotic swarms - beyond energy autonomy

Abstract: The paper considers trophallaxis in robot swarms, which is presented as a concept for resource sharing among individuals inspired by altruistic behaviour in natural populations. A number of elementary problems are identified, such as energy containment, robot morphology, rendezvous motion control and individual resource exchange behaviour. The CISSBot is presented as a design study as well as a proof of concept illustrating how a trophallactic exchange mechanism may be implemented based on batteries in commercially available form factor. A collison free proximity motion control is presented and illustrated by numerical simulation results. A probabilistic Markovian model including relevant effects; mobility, charging, battery exchange and energy consumption is presented and illustrated with numerical examples.

Automatic building detection in aerial and satellite images

Abstract: Automatic creation of 3D urban city maps could be an innovative way for providing geometric data for varieties of applications such as civilian emergency situations, natural disaster management, military situations, and urban planning. Reliable and consistent extraction of quantitative information from remotely sensed imagery is crucial to the success of any of the above applications. This paper describes the development of an automated roof detection system from single monocular electro-optic satellite imagery. The system employs a fresh approach in which each input image is segmented at several levels. The border line definition of such segments combined with line segments detected on the original image are used to generate a set of quadrilateral rooftop hypotheses. For each hypothesis a probability score is computed that represents the evidence of true building according to the image gradient field and line segment definitions. The presented results demonstrate that the system is capable of detecting small gabled residential rooftops with variant light reflection properties with high positional accuracies.

Archaeology via underwater robots: Mapping and localization within maltese cistern systems

Abstract: This paper documents the application of several underwater robot mapping and localization techniques used during an archaeological expedition. The goal of this project was to explore and map ancient cisterns located on the islands of Malta and Gozo. The cisterns of interest acted as water storage systems for fortresses, private homes, and churches. They often consisted of several connected chambers, still containing water. A sonar-equipped Remotely Operated Vehicle (ROV) was deployed into these cisterns to obtain both video footage and sonar range measurements. Four different mapping and localization techniques were employed including 1) Sonar image mosaics using stationary sonar scans, and 2) Simultaneous Localization and Mapping (SLAM) while the vehicle was in motion, 3) SLAM using stationary sonar scans, and 4) Localization using previously created maps. Two dimensional maps of 6 different cisterns were successfully constructed. It is estimated that the cisterns were built as far back as 300 B.C.

Home environment fall detection system based on a cascaded multi-SVM classifier

Abstract: Fall detection system for intelligent home care for elderly people is presented in this paper. The system includes human blob detection by non-parameter background substruction method, feature extraction from two minimum bounding boxes, and fall detection by a cascaded multi-SVM classifier. Besides falling down, other daily activities such as walk, jogging, sitting down, squatting down and immobility are also taken into consideration. A three-stage cascade of SVM classifiers is made to distinguish fall action from other activities. Each SVM classifier is first trained and tested separately to achieve its best classification performance by choosing proper features and corresponding kernel function. Then the combined classifier is trained to detect falls. A perfect correct identification rate of 98.13% on a real activity video set by experiments demonstrates the robustness and the utility of the system.

An image-based visual servoing scheme for following paths with nonholonomic mobile robots

Abstract: We present an image-based visual servoing controller enabling nonholonomic mobile robots with a fixed pinhole camera to reach and follow a continuous path on the ground. The controller utilizes only a small set of features extracted from the image plane, without using the complete geometric representation of the path. A Lyapunov-based stability analysis is carried out. The performance of the controller is validated and compared by simulations and experiments on a car-like robot equipped with a pinhole camera.

Dynamics analysis of a redundant parallel manipulator driven by elastic cables

Abstract: In this paper the dynamic analysis of a cable-driven parallel manipulator is studied in detail. The manipulator architecture is a simplified planar version adopted from the structure of large adaptive reflector (LAR), the Canadian design of next generation giant radio telescopes. This structure consists of a parallel redundant manipulator actuated by long cables. The dynamic equations of this structure are nonlinear and implicit. Long cables, large amounts of impelling forces and high accelerations raise more concern about the elasticity of cables during dynamic analysis, which has been neglected in the preceding works. In this paper, the kinematic analysis of such manipulator is illustrated first. Then the nonlinear dynamic of such mechanism is derived using Newton-Euler formulation. Next a simple model for cable dynamics containing elastic and damping behavior is proposed. The proposed model neither ignores longitude elasticity properties of cable nor makes dynamic formulations heavily complicated like previous researches. Finally, manipulator dynamic with cable dynamic is derived, and the cable elasticity effects are compared in a simulation study. The results show significant role of elasticity in a cable-driven parallel manipulator such as the one used in LAR mechanism.

Palmprint identification using Sobel operator

Abstract: Biometric is the science of measuring human physiological and/ or behavioral characteristics for the purpose of authentication and identification. One of the human's physiological characteristics, palmprint, is gaining popularity among researchers because it is features rich. Palmprint is unique and easy to capture using a conventional digital camera. It does not change much across time. In this paper, ten right hand images from one hundred individuals are acquired using a digital camera. The hand image is pre-processed to obtain the palmprint image. The palmprint image is enhanced and resized to 60 times 60 pixels. Different Sobel operators are applied to the resized palmprint image. The Sobel image is thresholded and represented using feature vector. All of the feature vectors are compared using Hamming Distance similarity. An accuracy of 94.84 percent can be achieved using the proposed method.

Achievable safety of driverless ground vehicles

Abstract: Safety is an important issue of driverless car. Yet, most current approaches fail to ensure safety even in a fully informed situation. In this paper we discuss how the safety criteria apply when the robot uses its on board sensors to evolve in an environment populated with static and moving obstacles. The sensors can only provide a partial and uncertain knowledge of the surroundings. We show that the usual safety notion does not apply for this relevant case and discuss which safety guarantees can be given and how to achieve them.

Tether tracking and control of ROSA robotic rover

Abstract: Mars is currently the centre of interest for space exploration. Tremendous efforts are still in progress to find clues of existence of life on Mars. Rovers are major sources of information of Mars. This paper focuses on a robotic roving vehicle robot for scientific applications (ROSA) having its initiative of European Space Agency (ESA). ROSA being a tethered rover makes possible to reduce the weight/size of rover because power is delivered through tether. Additionally, tether provides communication lines between the lander and the rover. Tethered robots require complex control system. This paper presents a specialized tracking system for rover's 40 m tether. The proposed system is capable of tether tracking within resolution of plusmn6 cm. The same strategy can also be used in other tethered robots for rescue, security, underwater, mines hunting and cleaning petroleum tanks after minor modifications.

Lane boundaries detection algorithm using vector lane concept

Abstract: A lane detection system is an important component of many intelligent transportation systems. In this paper, we present a robust and real-time lane tracking algorithm for any curved road. We use Non Uniform B-Spline (NUBS) interpolation method to construct the boundaries road lane. First, the Canny filter is employed to obtain edge map. Second, we apply parallel thinning algorithm into edge map to get the skeleton image. Once skeleton image is obtained, we introduce a new algorithm based on Vector Lane Concept to extract feature edge points that play the role as control points for NUBS interpolation process to represent left and right lane, separated. Finally, we estimate the curvature of left and right lane boundary for lane tracking. The result of this method can be used for Autonomous Guided Vehicles (AGV) system application.

Development of fuzzy-logic-based self tuning PI controller for servomotor

Abstract: Direct Current (DC) servomotors are widely used in robot manipulator applications. Servomotors use feedback controller to control either the speed or the position or both, and the basic continuous feedback control is PID controller. This paper discusses the modeling and simulation of DC servomotor control built using MATLAB/Simulink, and the analysis of controller performance, namely a PID controller, PI controller, fuzzy-scheduled PID controler, and a fuzzy-logic-based self tuning PI controller on the system. The singleton fuzzification is used as a fuzzifier. The center average is used as a defuzzifier. Two control modes are applied in sequential to the plant: speed control, and then position control. Simulation results show that fuzzy-logic-based self tuning PI controller has the best performance compared to conventional PID controller and fuzzy-scheduled PID controler.

Minimum-energy translational trajectory planning for battery-powered three-wheeled omni-directional mobile robots

Abstract: The minimum-energy translational trajectory planning algorithm is proposed for battery-powered three-wheeled omni-directional mobile robots (TOMRs). We have chosen a practical cost function as the total energy drawn from the batteries, in order to lengthen the operational time of a mobile robot with given batteries. After establishing the dynamic equations of TOMRs, the optimal control theory is used to solve the minimum-energy trajectory, which gives the velocity profile in analytic form. Various simulations are performed and the consumed energy is compared to other velocity trajectories. Simulation results reveal that the energy saving is achieved of up to 2.4% compared with loss-minimization control, and up to 4.3% compared with conventional trapezoidal velocity profile.

High level sensor data fusion for automotive applications using occupancy grids

Abstract: We describe a general architecture of vehicle perception system developed in the framework of the European project PReVENT-ProFusion. Our system consists of two main parts: the first part where the vehicle environment is mapped and moving objects are detected; and the second part where previously detected moving objects are verified and tracked. In this paper, we focus on the first part, using occupancy grid to model the vehicle environment, perform sensor data fusion and detect moving objects. Experimental results on a Volvo Truck equipped with laser scanner and radars show the effectiveness of our approach.

Simulation of workflow scheduling strategies using the MAST test management system

Abstract: Workflow simulation is an effective approach to investigate dynamic workflow scheduling and evaluate system performance. In this paper we report on a test management system for the evaluation of a range of workflow scheduling strategies based on multi-agent negotiation, where each resource agent performs local scheduling using dispatching rules. The newly developed test management system runs test cases on the manufacturing agent simulation Tool (MAST), which provides comprehensive support for performance measurement and data analysis reporting.

Coupled, non-linear control system design for autonomous underwater vehicle (AUV)

Abstract: Modern developments in the fields of control, sensing, and communication have made increasingly complex and dedicated underwater robot systems a reality. Used in a highly hazardous and unknown environment, the autonomy and dynamics of the robots is the key to mission success. Though the dynamics of underwater vehicle system is highly coupled and non linear in nature, decoupled control system strategy is widely used for practical applications. As autonomous underwater vehicles need intelligent control systems, it is necessary to develop control systems that really take into account the coupled and non-linear characteristics of the system. In this paper, we propose a control system with a nonlinear control strategy that takes into account the above factors. So far, AUV dynamics has often been derived under various assumptions on the motion of the vehicle. However, such assumptions may induce large modelling errors and may cause severe control problems in many practical applications. We propose to use both Lyapunov and state space back stepping based non linear control to overcome the modelling errors. The strategy will be tested through simulations for a flat-fish type AUV. Basic controller design and the simulation results will be discussed in the paper. A comparison of the results for conventional method and the proposed method will also be presented.

Fake finger detection using an electrotactile display system

Abstract: Fingerprint recognition is the most popular biometrics but the current fingerprint authentication system can still be easily circumvented by fake fingers. In this paper, we propose a novel method to detect fake finger using tactile sensation. It relies on an additional ability of a live finger, the sense of touch. Such tactile perception capability is absent in the dead or a totally fake finger. Based on this concept, an electrotactile display system capable of presenting tactile pattern is developed. This is then correlated with the pattern shown visually to the user. The system does not produce any visible, auditory or other clues and as such, its strength is only dependent on the number of visible patterns available for the user to select. Preliminary result obtained from the prototype system shows that the proposed approach is indeed able to detect gelatin fake finger worn over live fingers, even when the gelatin is only 1mm thick.

A SFLA-based fuzzy controller for balancing a ball and beam system

Abstract: The paper presents using the shuffled frog leaping algorithm (SFLA) to optimally tune parameters of a fuzzy logic controller stabilizing a ball and beam system at its equilibrium position. The SFLA is a meta-heuristic search method inspired from the memetic evolution of a group of frogs when seeking for food. It consists of a frog leaping rule for local search and a memetic shuffling rule for global information exchange. In this study, the rule base of the fuzzy controller is brought by expert experience, and the parameters of the controller, i.e. the membership function parameters and scaling gains, are optimally tuned by the SFLA such that a predefined criterion is minimized. Simulation results show that the designed fuzzy controller is able to balance the ball and beam system around its equilibrium state and the performance of the fuzzy controller is better than that of the well-known LQR controller.

Kalman filtering over a packet dropping network: A probabilistic approach

Abstract: We consider the problem of state estimation of a discrete time process over a packet dropping network. Previous pioneering work on Kalman filtering with intermittent observations is concerned with the asymptotic behavior of E[Pk], i.e., the expected value of the error covariance, for a given packet arrival rate. We consider a different performance metric, Pr[Pk les M], i.e., the probability that Pk is bounded by a given M, and we derive lower and upper bounds on Pr[Pk les M]. We are also able to recover the results in the literature when using Pr[Pk les M] as a metric for scalar systems. Examples are provided to illustrate the theory developed in the paper.

Image processing techniques for quality inspection of gelatin capsules in pharmaceutical applications

Abstract: Machine vision systems provide quality control and real-time feedback for industrial processes, overcoming physical limitations and subjective judgment of humans. In this paper, the image processing techniques for developing low-cost machine vision system for pharmaceutical capsule inspection is explored. By developing image processing techniques, and using PCs, custom USB 2.0 cameras with minimal hardware, a low-cost flexible system is developed. This paper discusses the two-part gelatin capsule inspection system that belongs to USB camera 2.0 and associated hardware, the PCs to acquire the image data of the capsule, image processing techniques using border tracing and approximating the capsule to a circle to perform inspection and a custom system controller to pass the accepted and rejected capsules to the appropriate bin.

A virtual laboratory platform and simulation software based on web

Abstract: This paper presents a virtual laboratory platform based on the B/S structure framework in distributed network, and the virtual laboratory platform includes the software and hardware resources. The virtual laboratory allows network terminal to access through the network. The two parts of the virtual laboratory are laboratory device interface platform and software platform. The design method of the virtual laboratory device interface platform is provided in the paper, and the paper has done the development of the software platform for virtual simulation experiment. The software platform of the virtual simulation experiment is developed with ASP.NET and C# programming language. In this platform, students can take experiment simulation process, preview experiment content, and put in the experiment report, online FAQs and so on.