Fang, J.Q., Li, Q.S., Liu, D., Jeary, A.P. & Wong, C.K. 2000, 'Wind effects on a very tall building and wavelet analysis', Institution of Civil Engineers. Proceedings. Structures and Buildings, vol. 140, no. 2, pp. 151-159.
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Hung, M.H., Orin, D.E. & Waldron, K.J. 2000, 'Efficient formulation of the force distribution equations for general tree-structured robotic mechanisms with a mobile base', IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics, vol. 30, no. 4, pp. 529-538.
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In this paper, an efficient and systematic formulation of the force distribution equations for general tree-structured robotic mechanisms 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. The force balance equations that govern the relationship between the contact forces and the resultant inertial forces/moments of the vehicle will be derived through a recursive and computationally efficient algorithm. Also, the joint torque constraints that specify the joint actuator limits, and contact friction constraints that may be used to avoid slippage and maintain contact, are efficiently incorporated in the formulation. Based on this formulation, several standard optimization techniques, such as linear programming or quadratic programming, can be applied to obtain the solution. An algorithm summarizing the results developed, and suitable for computer implementation, is included. The algorithm has been applied to an n-module actively articulated wheeled vehicle, and the computational cost evaluated. The efficiency of the algorithm is demonstrated with results showing real-time execution on a Pentium PC.
Kodagoda, K.R.S., Wijesoma, W.S. & Teoh, E.K. 2000, 'Stable fuzzy state space controllers for an AGV', Neural Networks for Signal Processing - Proceedings of the IEEE Workshop, vol. 2, pp. 672-681.
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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 for real time implementation. In this paper, we present a stable uncoupled direct fuzzy PD/PI control scheme for an outdoor AGV, which is a converted electrically powered golf-car. The controller performance was assessed both through simulations and experimental results. It was established that the fuzzy logic controller (FLC) yielded good performance even under uncertain and variable parameters in the model, unlike the computed torque technique (CTT) or conventional PID control. And in terms of real-time implementation the availability of custom fuzzy chips and the reduced computational complexity of the fuzzy controller as against the CTT, makes the fuzzy controller, an ideal choice amongst the two schemes.
Li, Q.S., Fang, J.Q. & Liu, D. 2000, 'Exact solutions for free vibration of single-degree-of-freedom systems with non-periodically varying parameters', Journal of Vibration and Control, vol. 6, no. 3, pp. 449-462.
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Li, Q.S., Fang, J.Q., Jeary, A.P., Wong, C.K. & Liu, D.K. 2000, 'Evaluation of wind effects on a supertall building based on full-scale measurements', Earthquake Engineering and Structural Dynamics, vol. 29, no. 12, pp. 1845-1862.
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This paper describes the results obtained from the full-scale measurements of wind effects on a 70-storey building in Hong Kong. The building which has a height of approximately 370 m is the second tallest structure in Hong Kong. The field data such as wind speed, wind direction and wind-induced acceleration responses have been measured since 1995 including the close passage of two typhoons; typhoon Sally and typhoon Kent. Detailed analysis of the field data is conducted. The full-scale measurements are compared with the wind tunnel results obtained in the Boundary Layer Wind Tunnel Laboratory at Western Ontario University. The amplitude-dependent characteristics of damping and natural frequency that were obtained by using the random decrement technique are investigated. Copyright (C) 2000 John Wiley and Sons, Ltd.
Li, Q.S., Fang, J.Q., Jeary, J.P., Wong, C.K. & Liu, D. 2000, 'Evaluation of wind effects on a super tall building based on full scale measurements', Earthquake Engineering and Structural dynamics, vol. 29, no. 12, pp. 1845-1862.
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Li, Q.S., Li, G.Q. & Liu, D. 2000, 'Exact solution for longitudinal vibration of rods coupled by translational springs', International Journal of Mechanical Science, vol. 42, no. 6, pp. 1135-1152.
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Li, Q.S., Liu, D., Fang, J.Q. & Tam, C.M. 2000, 'Multi-level optimal design of buildings with active control under winds using genetic algorithms', Journal Of Wind Engineering And Industrial Aerodynamics, vol. 86, no. 1, pp. 65-86.
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Li, Q.S., Liu, D., Fang, J.Q., Jeary, A.P. & Wong, C.K. 2000, 'Damping in buildings: its neural network model and AR model', Engineering Structures, vol. 22, no. 9, pp. 1216-1223.
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Li, Q.S., Liu, D., Leung, A., Zhang, N., Tam, C.M. & Yang, L.F. 2000, 'Modeling of structural response and optimization of structural control system using neural network and genetic algorithm', The Structural Design of Tall Buildings, vol. 9, pp. 279-293.
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Li, Q.S., Liu, D.K., Leung, A.Y., Zhang, N., Tam, C.M. & Yang, L.F. 2000, 'Modelling of structural response and optimization of structural control system using neural network and genetic algorithm', The Structural Design of Tall and Special Buildings, vol. 9, no. 4, pp. 279-293.
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In recognition of the increasing importance of accurate seismic vulnerability assessment, this paper deals with procedures and the application of inelastic acceleration and displacement spectra in the seismic assessment of buildings. An identification procedure is outlined, whereby an equivalent single degree of freedom (SDOF) system is devised to represent the building. The SDOF system characteristics (stiffness, strength, post-peak force response and ductility) are readily evaluated from observation of the seismic response of buildings and simple mechanics. The characteristics are then tuned using measurements from instrumented buildings. Based on the earthquake scenario and structural response characteristics, appropriate inelastic acceleration and displacement spectra are selected and used to predict the response. Comparison between the measured and predicted responses for the five buildings studied in the paper confirm the feasibility of the procedure and the realism of the results
Waldron, K. & Hubert, C. 2000, 'Control Of Contact Forces In Wheeled And Legged Off-road Vehicles', Experimental Robotics Vi, vol. 250, pp. 205-214.
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The use of variable configuration vehicles creates the possibility of direct control of the contact forces between the foot or wheel of a vehicle and the ground. That control is an important element of the coordination of practical walking machines. Cont
Wang, J. 2000, 'A Hybrid Method for Unconstrained Handwritten Numeral Recognition by Combining Structural and Neural "Gas" Classifiers', Pattern Recognition Letters, vol. 30, no. 7, pp. 625-635.
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Abstract: This paper presents a hybrid method for handwritten numeral recognition that combines two compensatory recognition algorithms by analysing their performance for several aspects. The skeleton-based structural recognition algorithm employed in this method is robust under distortion but sensitive to noise and flaws. On the other hand, the neural network classifier, which uses scaled binary images as features and the neural "gas" model for classification, is relatively immune to noise and flaws but sensitive to distortion. The different performances of the two algorithms for broken, connected or slanted numerals, and the measurement-level decision provided by the neural network are detected and combined with different strategies to develop matching rules for each recognition method. Five combination methods based on performance analysis are developed to meet different requirements. As the two algorithms have fairly compensatory properties, the proposed method improves the recognition rate and reliability by exploiting the advantages and avoiding the weaknesses of each classifier. The experimental results from a large set of data show the efficiency and robustness of the proposed method.
Dissanayake, G., Durrant-Whyte, H. & Bailey, T. 2000, 'Computationally efficient solution to the simultaneous localisation and map building (SLAM) problem', Proceedings - IEEE International Conference on Robotics and Automation, pp. 1009-1014.
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The theoretical basis of the solution to the simultaneous localisation and map building (SLAM) problem where an autonomous vehicle starts in an unknown location in an unknown environment and then incrementally build a map of landmarks present in this environment while simultaneously using this map to compute absolute vehicle location is now well understood. Although a number of SLAM implementations have appeared in the recent literature, the need to maintain the knowledge of the relative relationships between all the landmark location estimates contained in the map makes SLAM computationally intractable in implementations containing more than few tens of landmarks. In this paper, the theoretical basis and a practical implementation of a computationally efficient solution to SLAM is presented. The paper shows that it is indeed possible to remove a large percentage of the landmarks from the map without making the map building process statistically inconsistent. Furthermore, it is shown that the efficiency of the SLAM can be maintained by judicious selection of landmarks, to be preserved in the map, based on their information content.
Gibbens, P.W., Dissanayake, G.M.W.M. & Durrant-Whyte, H.F. 2000, 'A closed form solution to the single degree of freedom simultaneous localisation and map building (SLAM) problem', Proceedings of the IEEE Conference on Decision and Control, pp. 191-196.
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This paper presents a closed form solution to the estimation-theoretic simultaneous localisation and map building (SLAM) problem. The solution is obtained by explicit solution of the differential Riccati equation associated with then n-landmark SLAM problem. The solution describes and explains the many experimental and theoretical results obtained so far in the study of the SLAM problem. Further, the solution, for the first time, allows a precise means of analysing the performance of different SLAM algorithms and enables the design of efficient SLAM systems.
Liu, D., Zhang, N., Jeyakumaran, J.M. & Villanueva, L. 2000, 'Dynamics and Shift Control of Automatic Transmissions', Proc. of the Fifth International Conference on Motion and Vibration Control, International Conference on Motion and Vibration Control, UTS, Sydney, australia, pp. 597-602.
Liu, D., Zhang, N., Lu, F. & Q, S.L. 2000, 'Optimal Number and Positions of Actuators in Actively Controlled Structures', Proc. of the 5th International Conference on Motion and Vibration Control, International Conference on Motion and Vibration Control, UTS, Sydney, Australia, pp. 347-352.
Waldron, K.J. & Hubert, C. 2000, 'Scaling of robotic mechanisms', Proceedings - IEEE International Conference on Robotics and Automation, pp. 40-45.
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In this article we discuss some of the important similarity rules, or scaling laws that apply to robotic mechanisms. The important question is: 'What information can I derive about a smaller or larger system from a similarly configured, operational system?' The scaling laws elucidated here are useful for the initial configuration of new designs.
Wijesoma, W.S., Kodagoda, S. & Teoh, E.K. 2000, 'Design of Stable Fuzzy Controllers for an AGV', Proc. of IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS 2000), IEEE/RSJ International Conference on Intelligent Robots and Systems, IEEE, Japan, pp. 1044-1049.
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Fuzzy logic control is a relatively new technology and hence it needs rigorous comparative analyses with other well-established conventional control schemes. Furthermore, fuzzy controller stability analysis is a major hindrance for its popularity among control engineers. This paper shows how stable fuzzy controllers may be synthesized for a typical AGV from the perspective of variable structure systems (VSS) theory. VSS or sliding model control (SMC) is an established robust nonlinear control methodology. The AGV is characterized by highly nonlinear, coupled and configuration dependent dynamics, with uncertainty in model parameters. Similarity in performance of the fuzzy controllers to the SMC controller is demonstrated through experimental results obtained for steering control of the AGV
Williams, S.B., Newman, P., Dissanayake, G. & Durrant-Whyte, H. 2000, 'Autonomous underwater simultaneous localisation and map building', Proceedings - IEEE International Conference on Robotics and Automation, pp. 1793-1798.
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In this paper we present results of the application of a Simultaneous Localisation and Map building (SLAM) algorithm to estimate the motion of a submersible vehicle. Scans obtained from an on-board sonar are processed to extract stable point features in the environment. These point features are then used to build up a map of the environment while simultaneously providing estimates of the vehicle location. Results are shown from deployment in a swimming pool at the University of Sydney as well as from field trials in a natural environment along Sydney's coast. This work represents the first instance of a deployable underwater implementation of the SLAM algorithm.