Clark, S. & Dissanayake, G. 1999, 'Simultaneous localisation and map building using millimetre wave radar to extract natural features', Proceedings - IEEE International Conference on Robotics and Automation, vol. 2, pp. 1316-1321.
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This paper discusses the use of a 77GHz millimetre wave radar as a guidance sensor for autonomous land vehicle navigation. An extended Kalman filter (EKF) maintains an estimate of map features in addition to vehicle state. This map augmented EKF is implemented with radar reflectors, designed for high visibility from all orientations. An improvement on this approach enables natural features to be identified, using the polarisation of returned radar signals. Those that are suitable as navigational markers are used to update estimates of vehicle and feature locations. This method requires no a priori knowledge of the environment and no target infrastructure.
Dissanayake, G., Sukkarieh, S., Nebot, E. & Durrant-Whyte, H. 1999, 'New algorithm for the alignment of inertial measurement units without external observation for land vehicle applications', Proceedings - IEEE International Conference on Robotics and Automation, vol. 3, pp. 2274-2279.
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This paper describes a real time, on-the-fly, Roll and Pitch alignment algorithm for Inertial Measurement Units (IMUs) mounted on land vehicles. Unlike conventional strategies, the alignment is achieved without external observations. This is achieved by exploiting the non-holonomic constraints that govern the motion of a vehicle on a surface to obtain the Roll and Pitch of the IMU. The position of the vehicle along its path is still unobservable and the algorithm is effective only when there is sufficient excitation in all degrees of freedom. However, with the proposed alignment algorithm, the IMU is able to provide sufficiently accurate position information for substantially longer periods of time compared with conventional methods. Experimental results are provided along with a comparison of an IMU/GPS navigation loop showing the effectiveness of the algorithm.
Fang, J.Q., Li, Q.S. & Liu, D.K. 1999, 'Non-spillover control design of tall buildings in modal space', Wind and Structures, An International Journal, vol. 2, no. 3, pp. 189-200.
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In this paper, a new algorithm for active control design of structures is proposed and investigated. The algorithm preserves the decoupling property of the modal vibration equation and eliminates the spillover problem, which is the main shortcoming in the independent modal space control (IMSC) algorithm. With linear quadratic regulator(LQR) control law, the analytical solution of algebraic Riccati equation and the optimal actuator control force are obtained, and the control design procedure is significantly simplified. A numerical example for the control design of a tall building subjected to wind loads demonstrates the effectiveness of the proposed algorithm in reducing the acceleration and displacement responses of tall buildings under wind actions.
Fang, J.Q., Li, Q.S., Jeary, A.P. & Liu, D.K. 1999, 'Damping of tall buildings: Its evaluation and probabilistic characteristics', Structural Design of Tall Buildings, vol. 8, no. 2, pp. 145-153.
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This paper describes randomness of damping and its probabilistic characteristics in buildings based on full scale measurements. Amplitude dependent behavior of damping at different amplitude level is presented and discussed, and probabilistic characteristics of the damping at high amplitude plateau are analyzed. The obtained probability density function (PDF) of damping shows that the PDF of damping at high amplitude can be well represented by the Normal distribution (Gaussian distribution).
Fang, J.Q., Li, Q.S., Jeary, A.P., Liu, D.K. & Wong, C.K. 1999, 'Probabilistic characteristics of damping in buildings', Wind and Structures, An International Journal, vol. 2, no. 2, pp. 127-131.
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This paper describes probabilistic characteristics of damping in a tall building based on the results of full-scale measurement. It is found, through statistical analysis of the damping data, that the probability density function(PDF) of damping at the high amplitude plateau can be well represented by Normal distribution (Gaussian distribution). A stochastic damping model is proposed to estimate amplitude-dependent damping for practical application.
Huang, S. & Zhang, S. 1999, 'Some control problems for symmetric circulant composite systems', Kongzhi Lilun Yu Yingyong/Control Theory and Applications, vol. 16, no. 4.
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In this paper, we study the output regulation for symmetric circulant composite systems and the quadratic stability and the quadratic stabilization for uncertain symmetric circulant omposite systems. It is shown that because of the special structure of the system, the output regulator roblems for such a system can be transfered to the output regulator problem for sys tems with lower rder. The quadratic stability for such a system can be simplified by considering the quadratic stability of several independent systems of lower order. And the quadratic stabilization controller of such a system can be constructed by the quadratic stabilization controller of systems with lower order.
Huang, S., Lam, J., Yang, G.H. & Zhang, S. 1999, 'Fault tolerant decentralized H∞ control for symmetric composite systems', IEEE Transactions on Automatic Control, vol. 44, no. 11, pp. 2108-2114.
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This note discusses a class of large-scale systems composed of symmetrically interconnected identical subsystems. We consider the decentralized H∞control design problem and study the fault tolerance of the resulting system. By exploiting the special structure of the systems, a sufficient condition for the existence of a decentralized H∞controller is derived. Moreover, for the nominal case as well as for contingent situations characterized by control channel failures, the poles and the H∞-norm of the closed-loop system can be calculated easily based on certain systems of reduced dimensions. Consequently, the tolerance to actuator failure can be easily tested.
Hung, M.H., Orin, D.E. & Waldron, K.J. 1999, 'Force distribution equations for general tree-structured robotic mechanisms with a mobile base', Proceedings - IEEE International Conference on Robotics and Automation, vol. 4, pp. 2711-2716.
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An efficient formulation of the force distribution equations for actively-coordinated vehicles is presented. The applicable platforms include not only systems with star topologies, such as walking machines that have multiple legs with a single body, but also general tree-structured mechanisms, such as variably-configured wheeled vehicles having multiple modules. Based on this formulation, several standard optimization techniques, such as linear programming or quadratic programming, can be applied to obtain the solution. The efficiency of the formulation is demonstrated with results showing real-time execution on a Pentium PC.
Li, Q., Cao, H., Li, G., Li, S. & Liu, D. 1999, 'Optimal design of wind-induced vibration control of tall buildings and high-rise structures', Wind and Structures, An International Journal, vol. 2, no. 1, pp. 69-83.
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The most common used control device on tall buildings and high-rise structures is active and passive tuned mass damper (ATMD and TMD). The major advantages of ATMD and TMD are discussed. The existing installations of various passive/active control devices on real structures are listed. A set of parameter optimization methods is proposed to determine optimal parameters of passive tuned mass dampers under wind excitation. Simplified formulas for determining the optimal parameters are proposed so that the design of a TMD can be carried out easily. Optimal design of wind-induced vibration control of frame structures is investigated. A thirty-story tall building is used as an example to demonstrate the procedure and to verify the efficiency of ATMD and TMD with the optimal parameters.
Li, Q.S., Fang, J.Q. & Liu, D.K. 1999, 'Evaluation of structural dynamic responses by stochastic finite element method', Structural Engineering and Mechanics, vol. 8, no. 5, pp. 477-490.
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The uncertainties associated with structural parameters and dynamic loading are identified and discussed. Structural parametric uncertainties are treated as random variables and dynamic wind load is simulated as a random process. Dynamic wind-induced responses of structures with parametric uncertainties are investigated by using stochastic finite element method. The formulas for structural dynamic reliability analysis considering the randomness of structural resistance and loading are proposed. Two numerical examples of high-rise structures are presented to illustrate the proposed methodology. The calculated results demonstrate that the variation in structural parameters indeed influences the dynamic response and the first passage probability evaluation of structures.
Li, Q.S., Liu, D.K. & Fang, J.Q. 1999, 'Optimum design of actively controlled structures using genetic algorithms', Advances in Structural Engineering, vol. 2, no. 2, pp. 109-118.
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Optimal placement of actuators in actively controlled structures is a mixed-discrete optimization problem; it has the characteristics of nonlinear, non-continuous, and so on. For this type of optimization problem, traditional optimization methods based on mathematical programming may not be effective. In this paper, the complexity, discreteness and non-linearity of the optimal design problems of actuator placement are investigated. An optimal control algorithm and active tendon controllers are applied to control the response of a 16-storey building under earthquake loads. A mathematical model of optimal actuator configuration is established. Based on the special optimization problem of actuator configuration in an actively controlled structure, a modified genetic algorithm is presented and applied to solve the problems. A design procedure/method is presented for this kind of optimization problem, and the suitability of this method for the optimization problem is investigated. The numerical calculation and analysis are carried out for the building controlled by active tendon control mechanisms, and the results are discussed and analyzed in detail.
Li, Q.S., Liu, D.K., Fang, J.Q., Jeary, A.P. & Wong, C.K. 1999, 'Using neural networks to model and predict amplitude dependent damping in buildings', Wind and Structures, An International Journal, vol. 2, no. 1, pp. 25-40.
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In this paper, artificial neural networks, a new kind of intelligent method, are employed to model and predict amplitude dependent damping in buildings based on our full-scale measurements of buildings. The modelling method and procedure using neural networks to model the damping are studied. Comparative analysis of different neural network models of damping, which includes multi-layer perception network (MLP), recurrent neural network, and general regression neural network (GRNN), is performed and discussed in detail. The performances of the models are evaluated and discussed by tests and predictions including self-test, `one-lag' prediction and `multi-lag' prediction of the damping values at high amplitude levels. The established models of damping are used to predict the damping in the following three ways: (1) the model is established by part of the data measured from one building and is used to predict the another part of damping values which are always difficult to obtain from field measurements: the values at the high amplitude level. (2) The model is established by the damping data measured from one building and is used to predict the variation curve of damping for another building. And (3) the model is established by the data measured from more than one buildings and is used to predict the variation curve of damping for another building. The prediction results are discussed.
Madhavan, R., Dissanayake, G., Durrant-Whyte, H., Roberts, J., Corke, P. & Cunningham, J. 1999, 'Issues in autonomous navigation of underground vehicles', Mineral Resources Engineering, vol. 8, no. 3, pp. 313-324.
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This paper describes current research at the Australian Centre for Field Robotics (ACFR) in collaboration with the Commonwealth Scientific and Industrial Research Organisation (CSIRO) within the Cooperative Research Centre (CRC) for Mining Technology and Equipment (CMTE) towards achieving autonomous navigation of underground vehicles, like a Load-Haul-Dump (LHD) truck. This work is being sponsored by the mining industry through the Australian Mineral Industries Research Association Limited (AMIRA). Robust and reliable autonomous navigation can only be realised by achieving high level tasks such as path-planning and obstacle avoidance. This requires determining the pose (position and orientation) of the vehicle at all times. A minimal infrastructure localisation algorithm that has been developed for this purpose is outlined and the corresponding results are presented. Further research issues that are under investigation are also outlined briefly.
Madhavan, R., Nettleton, E., Nebot, E., Dissanayake, G., Cunningham, J., Durrant-Whyte, H., Corke, P. & Roberts, J. 1999, 'Evaluation of internal navigation sensor suites for underground mining vehicle navigation', Proceedings - IEEE International Conference on Robotics and Automation, vol. 2, pp. 999-1004.
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This paper describes a series of trials that were done at an underground mine in New South Wales, Australia. Experimental results are presented from the data obtained during the field trials and suitable sensor suites are evaluated.
Scheding, S., Dissanayake, G., Nebot, E. & Durrant-Whyte, H. 1999, 'An Experiment In Autonomous Navigation Of An Underground Mining Vehicle', IEEE Transactions On Robotics And Automation, vol. 15, no. 1, pp. 85-95.
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This paper describes the theoretical development and experimental evaluation of a navigation system for an autonomous load, haul, and dump truck (LHD) based on the results obtained during extensive in-situ field trials. The particular contributions of th
Schmiedeler, J.P. & Waldron, K. 1999, 'The Mechanics Of Quadrupedal Galloping And The Future Of Legged Vehicles', International Journal Of Robotics Research, vol. 18, no. 12, pp. 1224-1234.
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Previous studies have noted that biological quadrupeds adjust their gaits when encountering drag in their locomotion. This paper investigates the hypothesis that these gait adjustments allow the legs to operate at an optimal working length when generatin
Waldron, K. 1999, 'Drafting A New Plan For Design', Mechanical Engineering, pp. 37-38.
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Wang, J. 1999, 'Mending Broken Handwriting with a Macrostructure Analysis Method to Improve Recognition', Pattern Recognition Letters, vol. 20, no. 8, pp. 855-864.
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Abstract: Broken characters always create problems in handwriting recognition systems, especially those using boundary and/or skeleton information. This paper presents a macrostructure analysis (MSA) mending method based on skeleton and boundary information and an MSA that investigates the stroke tending direction and other properties of handwritings. A new skeleton end extension algorithm is introduced, which compensates the defectiveness of the skeletonization algorithm and obtains a satisfactory skeleton. When combined with suitable parameters, improved performance from a handwriting classifier is achieved. The experimental results from over 13000 numerals show the efficiency and robustness of the proposed method, raising recognition rates by over 10% for broken handwritten digits, from 74.8% to 86.4%.
Wijesoma, W.S., Kodagoda, K.R.S. & Teoh, E.K. 1999, 'Un-coupled fuzzy controller for longitudinal and lateral control of a golf car-like AGV', IEEE Conference on Intelligent Transportation Systems, Proceedings, ITSC, pp. 142-147.
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The development of techniques for lateral and longitudinal control of vehicles has become an important and active research topic in the face of emerging markets for advanced AGVs and mobile robots. The primary focus is on the development of an intelligent control scheme, which is insensitive to parametric uncertainty, load and parameter fluctuations and most importantly amenable to real time implementation. We have reviewed promising control schemes for steering and speed control of mobile robots. In this paper, we present an effective uncoupled direct fuzzy PD/PI control scheme for a particular outdoor AGV, which is a converted electrically powered golf-car. The controller performance is assessed against the required performance criteria and another nonlinear technique, viz. the computed torque technique (CTT).
Kodagoda, S., Wijesoma, W.S. & Teoh, E.K. 2005, 'Robust Un-Coupled Fuzzy Controller for Longitudinal and Lateral Control of an AGV', Lecture Notes in Computer Science 1625, International Conference on Computational Intelligence, Theory and Applications, Springer, Germany, pp. 370-381.
Ranasinghe, R.S., Andrew, L.L.H. & Everitt, D. 1999, 'Distributed contention-free traffic scheduling in IEEE 802.11 multimedia networks', IEEE Workshop on Local and Metropolitan Area Networks, pp. 18-28.
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© 1999 IEEE. Wireless local area networks are a promising solution to support advanced data services in mobile environments. The IEEE 802.11 wireless LAN standard is emerging as a mature technology to support delay sensitive network services. In order to support these services the standard has proposed the use of a polling scheme; however, existing polling schemes require high communication overheads or suffer from unfairness. In this paper, we propose a distributed fair queueing algorithm distributed deficit round robin, which is compatible with the 802.11 medium access control rules. Software simulation of this scheme shows that it can manage a heterogeneous mix of delay sensitive traffic.
Ranasinghe, R.S., Andrew, L.L.H. & Everitt, D. 1999, 'Impact of polling strategy on capacity of 802.11 based wireless multimedia LANs', IEEE International Conference on Networks, ICON, pp. 96-103.
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Wireless local area networks are a viable technology to support multimedia traffic. One of the prominent wireless local area network standards being adopted as a mature technology is the IEEE 802.11 standard. In wireless multimedia networks, mobile stations will be capable of generating a heterogeneous traffic mix and therefore it is crucial to devise an efficient bandwidth allocation scheme to satisfy the quality of service requirements of each traffic class. In this paper we present a distributed fair queuing scheme which is compatible with the 802.11 standard and can manage bandwidth allocation for delay-sensitive traffic. The performance of the proposed scheme is evaluated by simulation, showing that a distributed version of deficit round robin outperforms the standard round robin service discipline from a capacity viewpoint. © 1999 IEEE.
Wijesoma, W.S. & Kodagoda, S. 1999, 'Synthesis of Stable Fuzzy PD/PID control laws for Robotic Manipulators from a Variable Structure Systems Standpoint', Lecture Notes in Computer Science 1625, International Conference on Computational Intelligence, Theory and Applications,, Springer, Germany, pp. 495-511.