Crowther, A.R., Zhang, N., Liu, D. & Jeyakumaran, J.M. 2004, 'Analysis and simulation of clutch engagement judder and stick-slip in automotive powertrain systems', Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering, vol. 218, no. 12, pp. 1427-1446.
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Clutch engagement judder and stick-slip are investigated analytically and numerically to examine the influencing factors on these phenomena. Models are developed for a four degree-of-freedom (4DOF) torsional system with slipping clutch and for a powertrain with automatic transmission system. Stability analysis is performed to demonstrate that clutch judder is dependent on the slope of the friction coefficient and the analysis is verified with numerical simulations. An algorithm for modelling stick-slip is developed and is used in numerical simulations which show that the likelihood of stick-slip is increased by clutch pressure fluctuations, judder approaching engagement, and external torque fluctuations. Numerical simulations for second to thin gear up shifts demonstrate that the likelihood of stick-slip to occur from clutch engagement is increased by clutch applied pressure fluctuations, judder approaching engagement, and external torque fluctuations and that the likelihood of stick-slip occurring is decreased dramatically by applied pressure ramps proximus to the engagement point.
Kodagoda, S., Balasuriya, A. & Wijesoma, W.S. 2004, 'Road Boundary Detection and Tracking Using LADAR Sensing', IEEE Transactions on Robotics & Automation, vol. 20, no. 3, pp. 456-464.
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Li, Q.S., Liu, D., Tang, J., Zhang, N. & Tam, C.M. 2004, 'Combinatorial optimal design of number and positions of actuators in actively controlled structures using genetic algorithms', Journal Of Sound And Vibration, vol. 270, no. 4-5, pp. 611-624.
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In this paper, the optimal design of the numbers and positions of actuators in actively controlled structures is formulated as a three-level optimal design problem. Features of this design problem such as discreteness, multi-modality and hierarchical structure are discussed. A two-level genetic algorithm (TLGA) is proposed for solving this problem. The concept, principle and solution process of the TLGA are described. A case study is presented, in which a building is subjected to earthquake excitation and controlled by active tendon actuators. The results of this study show that: (1) the design problem for optimizing number and configuration of actuators simultaneously in actively controlled structures has the features of non-linearity, mixed-discreteness and multi-modality; (2) a three-level design model can give a reasonable description for this kind of design problem; (3) TLGA is an effective algorithm for solving the combinatorial optimization problem.
Nichol, J.G., Palmer, L.R. & Waldron, K.J. 2004, 'Design of a leg system for quadruped gallop', Chinese Journal of Mechanical Engineering (English Edition), vol. 17, no. SUPPL., pp. 1-4.
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Ohio State (OSU) and Stanford Universities are cooperating to understand quadruped galloping through the design of a self-contained, biomimetic, galloping robot. The leg for this quadruped was first designed at Ohio State University (OSU). A second-generation leg, with the same functional geometry, has been designed and tested at Stanford University. The objective of these tests was to determine that the single leg would be capable of prolonged operation at a velocity of 5 m/s, and that the control system, developed in simulation, would function under real-world conditions. The mechanical design of the quadruped is based on properties of biological quadruped animal legs. Important biomimetic design characteristics include minimal impact loss, elastic energy storage, and low inertia. The cable linkage, which works against a large spring to flex the knee, is uncoupled from the front-to-back hip actuator through a parallelogram-like cable mechanism. The controller developed for the leg is a direct adaptive fuzzy controller. The direct adaptive approach does not require system identification and can use heuristics to successfully control a complex system. With this controller, a single 2DOF leg constrained in yaw, pitch, roll and transverse translation can be successfully controlled. This controller was executed once each cycle at the top-of-flight. Parameters set by the controller were passed to PD controllers at each of the 2 joints: the hip and cable-actuated knee. The control of this leg required only 7 × 5 × 3 = 105 rules, each with a corresponding output for thigh and knee angle. This controller was implemented on an embedded processor attached to the leg. The leg reached a speed of 3 m/s. Modifications to the leg will increase this speed. The controller successfully adapted to the leg.
Nichol, J.G., Waldron, K., Singh, S.P., Palmer, L.R. & Orin, D.E. 2004, 'System Design of a Quadrupedal Galloping Machine', International Journal of Robotics Research, vol. 23, no. 10-11, pp. 1013-1028.
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In this paper we present the system design of a machine that we have constructed to study a quadrupedal gallop gait. The gallop gait is the preferred high-speed gait of most cursorial quadrupeds. To gallop, an animal must generate ballistic trajectories with characteristic strong impacts, coordinate leg movements with asymmetric footfall phasing, and effectively use compliant members, all the while maintaining dynamic stability. In this paper we seek to further understand the primary biological features necessary for galloping by building and testing a robotic quadruped similar in size to a large goat or antelope. These features include high-speed actuation, energy storage, on-line learning control, and high-performance attitude sensing. Because body dynamics are primarily influenced by the impulses delivered by the legs, the successful design and control of single leg energetics is a major focus of this work. The leg stores energy during flight by adding tension to a spring acting across an articulated knee. During stance, the spring energy is quickly released using a novel capstan design. As a precursor to quadruped control, two intelligent strategies have been developed for verification on a one-legged system. The Levenberg-Marquardt on-line learning method is applied to a simple heuristic controller and provides good control over height and forward velocity. Direct adaptive fuzzy control, which requires no system modeling but is more computationally expensive, exhibits better response. Using these techniques we have been successful in operating one leg at speeds necessary for a dynamic gallop of a machine of this scale. Another necessary component of quadruped locomotion is high-resolution and high-bandwidth attitude sensing. The large ground impact accelerations, which cause problems for any single traditional sensor, are overcome through the use of an inertial sensing approach using updates from optical sensors and vehicle kinematics
Vertechy, R., Castelli, V.P. & Waldron, K. 2004, 'Electro/Magneto-Sensitive Elastomers and Lagrangian Electro/Magneto-Statics', Chiang Mai Journal of Science, vol. 32, no. 3, pp. 287-292.
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Waldron, K. 2004, 'Untitled - Editorial', Mechanism And Machine Theory, vol. 39, no. 4, pp. 341-341.
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Wang, J. 2004, 'Pseudolite Augmentation for GPS Aided Aerial Photogrammetry: An Analysis of Systematic Errors.', Geomatics Research Australasia, vol. 81, pp. 30-44.
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GPS has been widely used as a geo-referencing tool in aerial surveying. However, the accuracy and availability of GPS positioning cannot meet the stringent requirements of large-scale photogrammetry. Ground-based pseudolites can strengthen measurement geometry for GPS based airborne geo-referencing systems. As a result, positioning accuracy and reliability can be improved, especially in the vertical component. However, as pseudolites are comparatively close to receivers, some challenging issues in systematic error analyses and modeling need to be further investigated. In this paper, the major systematic errors related to pseudolites, such as tropospheric delay, multipath and pseudolite location errors are analysed, and their impacts on the performance of an integrated GPS/Pseudolite airborne geo- reference system are presented.
Wang, J. 2004, 'Web-based Resources on GPS/INS Integration', GPS Solutions, vol. 8, no. 3, pp. 189-191.
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The integrated GPS/INS system has become an indispensable tool for providing precise and continuous position, velocity and attitude information for many positioning and navigation applications, from surveying and mapping to vehicle navigation, guidance and control. There is an extensive variety of websites that are directly or indirectly related to the technologies and applications of GPS/INS integration. This column presents a selection of the publicly available web-based resources on research-based activities for GPS/INS integration. The selection encompasses those international universities and companies that provide electronic versions of their publications.
Wijesoma, W.S., Kodagoda, S. & Balasuriya, A. 2004, 'Road Boundary Detection and Tracking Using LADAR Sensing', IEEE Transactions On Robotics, vol. 20, no. 3, pp. 456-464.
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Road-boundary detection is an integral and important function in advanced driver-assistance systems and autonomous vehicle navigation systems. A prominent feature of roads in urban, semi-urban, and similar environments, such as in theme parks, campus sites, industrial estates, science parks, and the like, is curbs on either side defining the road's boundary. Although vision is the most common and popular sensing modality used by researchers and automotive manufacturers for road-lane detection, it can pose formidable challenges in detecting road curbs under poor illumination, bad weather, and complex driving environments. This paper proposes a novel method based on extended Kalman filtering for fast detection and tracking of road curbs using successive range/bearing readings obtained from a scanning two-dimensional ladar measurement system. As compared with millimeter wave radar methods reported in the literature, the proposed technique is simpler and computationally more efficient. This is the first of its kind reported in the literature. Qualitative experimental results are presented from the application of the technique to a campus site environment to demonstrate the viability, effectiveness, and robustness.
Alempijevic, A. 2004, 'High-Speed Feature Extraction in Sensor Coordinates for Laser Rangefinders', Conference Proceedings, Australasian Conference on Robotics and Automation (ACRA 2004), Australasian Conference on Robotics and Automation, Australian Robotics & Automation Association, Canberra, Australia, pp. 1-6.
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Alempijevic, A. & Dissanayake, G. 2004, 'An Efficient Algorithm for Line Extraction from Laser Scans', Proceedings of the 2004 IEEE Conference on Robotics, Automation and Mechatronics (RAM), IEEE Conference on Robotics, Automation and Mechatronics, IEEE R&A Society Singapore Chapter, Singapore, pp. 970-974.
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In this paper, an algorithm for extracting line segments from information gathered by a laser rangefinder is presented. The range scan is processed to compute a parameter that is invariant to the position and orientation of straight lines present. This parameter is then used to identify observations that potentially belong to straight lines and compute the slope of these lines. Log-Hough transform, that only explores a small region of the Hough space identified by the slopes computed, is then used to rind the equations of the lines present. The proposed method thus combines robustness of the Hough transform technique with the inherent efficiency of line fitting strategies while carrying out all computation in the sensor coordinate frame yielding a fast and robust algorithm for line extraction from laser range scans. Two practical examples are presented to demonstrate the efficacy of the algorithm and compare its performance to the traditional techniques.
Dissanayake, G.M., Chen, L., Pedrycz, W., Fayek, A.R. & Russell, A.D. 2004, 'Fuzzy logic modeling of causal relationships-case study: Reasoning about construction performance', NAFIPS 2004: ANNUAL MEETING OF THE NORTH AMERICAN FUZZY INFORMATION PROCESSING SOCIETY, VOLS 1AND 2, pp. 605-610.
Fang, G., Dissanayake, G. & Lau, H. 2004, 'A behaviour-based optimisation strategy for multi-robot exploration', 2004 IEEE Conference on Robotics, Automation and Mechatronics, pp. 875-879.
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To efficiently explore an unknown environment with a team of robots, a coordinated strategy that maximises the exploration area is required. This is a difficult optimisation problem, as there may exist many suboptimal solutions. In order to reduce the search space to a region that is near the optimal, a behaviour-based exploration strategy is used to define the region in which an optimal solution can be found. A numerical optimisation technique is then used to find the solution in this region. In particular, the proposed strategy uses a potential-fields technique to obtain a coarse movement direction for each robot. A nonlinear optimisation method is then used to calculate the velocity and angle deviation from the coarse direction to achieve the maximum exploration for each move. Simulation results have shown that the proposed method provides an efficient exploration strategy.
Furukawa, T., Bourgault, F., Durrant-Whyte, H. & Dissanayake, G. 2004, 'Dynamic allocation and control of coordinated UAVs to engage Multiple targets in a time-optimal manner', Proceedings of the IEEE International Conference on Robotics and Automation - Vol 3, IEEE International Conference on Robots and Automation, IEEE, New Orleans, pp. 2353-2358.
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This paper presents the real-time control of cooperative unmanned air vehicles (UAV) that dynamically engage multiple targets in a time-optimal manner. Techniques to dynamically allocate vehicles to targets and to subsequently find the time-optimal control actions are proposed. The decentralization of the proposed control strategy is further presented such that the vehicles can be controlled in real-time without significant time delay. The proposed strategy is men applied to various practical battlefield problems, and numerical results show the efficiency of the proposed strategy.
Gong, Z., Mr, J.I., Scheding, S., Rye, D., Durrant-Whyte, H. & Dissanayake, G. 2004, 'A heuristic rule-based switching and adaptive PID controller for a large autonomous tracked vehicle: From development to implementation', IEEE Conference on Control Applications - International Symposium on Intelligent Control Computer Aided Control Systems Design, IEEE International Conference on Control Applications, IEEE, Taipei,Taiwan, pp. 1272-1277.
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An innovative and effective algorithm to control the speed and heading of B large tracked vehicle is presented. This is part of a larger control system that converts a manual driving vehicle into B computer controlled platform to perform autonomous functions in unshmehlred junglelike terrains Heuristic rule-based switching and adaptive PID eontrol methods m e used in this algorithm. The control system has been physically implemented and extensive field trials proved that the algorithm is robust and effective with excellent performance under various terrain conditions.
Ha, Q.P., Trinh, H. & Dissanayake, G. 2004, 'A low-order linear functional observer for time delay systems', 2004 5th Asian Control Conference, pp. 948-956.
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This paper presents an efficient technique to design loworder state function observers for linear time-delay systems. Assuming the existence of a linear state feedback controller to achieve stability or some control performance criteria of the time-delay system, a design procedure is proposed for reconstruction of the state feedback control action. The procedure involves solving an optimisation problem with the objective to generate a matrix that is as close as possible to the given feedback gain of the required feedback controller. A condition for robust stability of the time-delay system using the observer-based control scheme is given. The attractive features of the proposed design procedure are that the resulted linear functional state observer is of a very low order and it requires information of a small number of outputs. Numerical examples are given to demonstrate the design procedure and its merits.
Ha, Q.P., Trinh, H.M. & Dissanayake, G. 2004, 'A Low-Order Linear Functional Observer for Time Delay Systems', Proceedings of the 5th Asian Control Conference, Asian Control Conference, IEEE, Melbourne, Australia, pp. 947-955.
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Scott, 1)there are two Names H Trinh as stapled to front yellow page. & 2) the page numbers are the same as physically on the print off of Ha's other Public in this Conf "Simultaneous State... " !!
Huang, S., James, M. & Jiang, Z. 2004, 'L -Bounded Robust Control of Nonlinear Cascade Systems', Proceedings of the 5th Asian Control Conference, Asian Control Conference, ASCC 2004, Melbourne, Australia, pp. 531-538.
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Huang, S., James, M., Nesic, D. & Dower, P. 2004, 'Measurement Feedback Controller Design to Achieve Input to State Stability', 43rd IEEE Conference on Decision and Control, IEEE Conference on Decision and Control, IEEE, Atlantis, Paradise Island, Bahamas, pp. 2515-2520.
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Huang, S., James, M.R. & Jiang, Z.P. 2004, 'L∞-bounded robust control of nonlinear cascade systems', 2004 5th Asian Control Conference, pp. 532-539.
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In this paper, we consider the L ∞ -bounded robust control problem for a class of nonlinear cascade systems with disturbances. Sufficient conditions are provided under which a hard bound is imposed on the system performance measure. The backstepping approach is used for controller design. Examples are provided to illustrate the method.
Huang, S., Wang, Z. & Dissanayake, G. 2004, 'Time Optimal Robot Motion Control in Simultaneous Localization and Map Building (SLAM) Problem', Proceedings of 2004 IEEE/RSJ International Conference on Intelligent Robots and Systems, IEEE/RSJ International Conference on Intelligent Robots and Systems, Publication Committee of IROS 2004, Sendai, Japan, pp. 3110-3115.
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This paper provides a technique for minimal time robot motion control in the estimation-theoretic based simultaneous localizations and map building (SLAM) problem. We consider the scenario that the robot needs to go to a destination which is a prescribed location in the coordinate system referenced by its starting position. The task of the robot is to reach the destination within minimal time while localizing itself and building a map of the environment with a prescribed accuracy. This task may be a real navigation task or may be a subtask in a SLAM problem of a large unknown environment. A global sub-optimal control law is derived using dynamic programming techniques
Kulatunga, A.K., Liu, D. & Dissanayake, G. 2004, 'Simulated Annealing Algorithm Based Multi-Robot Coordination', Preprints of the 3rd IFAC Symposium on Mechatronic Systems, The 3rd IFAC Symposium on Mechatronic Systems, International Federation of Automatic Control (IFAC), Sydney, Australia, pp. 411-415.
Kwok, N. & Dissanayake, G. 2004, 'An Efficient Multiple Hypothesis Filter for Bearing-only SLAM', Proceedings of the 2004 IEEE/RSJ International Conference on Intelligent Robots and Systems, IEEE/RSJ International Conference on Intelligent Robots and Systems, IEEE, Sendai, Japan, pp. 736-741.
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This paper presents a multiple hypothesis approach to solve the simultaneous localisation and mapping (SLAM) problem with a bearing-only sensor. The main contribution of the paper is to provide a remedy for the landmark initialisation problem that occurs due to the absence of range information, in a computationally efficient manner. Each landmark is initialised in the form of multiple hypotheses distributed along the direction of the bearing measurement. Using subsequent measurements, the validity of the hypotheses is evaluated based on the sequential probability ratio test (SPRT). Consequently, the best approximation to the landmark location is maintained. This approach enables an extended Kalman filler (EKF) to be used for bearing-only SLAM providing a computational efficient solution. Simulation and experimental results, from using a camera as the bearing-only sensor mounted on a Pioneer robot are included to demonstrate the effectiveness of the proposed technique.
Kwok, N., Liu, D., Fang, G. & Dissanayake, G. 2004, 'Path Planning for Bearing-Only Simultaneous Localisation and Mapping', Proceedings of the 2004 IEEE Conference on Robotics, Automation and Mechatronics (RAM), IEEE Conference on Robotics, Automation and Mechatronics, IEEE, Singapore, pp. 828-833.
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Simultaneous localisation and mapping (SLAM) is the process of estimating the pose of a mobile robot and the locations of landmarks by using sensors. When SLAM is cast as an information extraction procedure, its quality can be defined as the amount of uncertainty contained in the resultant estimation. Due to the characteristic of the bearing-only sensor and the geometry of the environment, the estimation uncertainty relies critically on the amount of information obtained from measurements and the efficiency of information extraction by the estimator. These quantities are dependent on the relative position between the robot and the landmarks, i.e., the path of the robot motion. Therefore, a well planned path of motion for the robot can significantly improve the SLAM quality. A genetic algorithm is adopted in this research to design a near-optimal one-step-ahead robot path subject to a multiple of planning objectives. The use of genetic algorithm together with a Pareto set, is proved to be efficient in reducing the estimation uncertainty and improving the quality of SLAM by simulation results.
Li, R., Chen, W., Yu, M. & Liu, D. 2004, 'Fuzzy Intelligent Control of Automotive Vibration Via Magneto-Rheological Damper', Proceedings of the 2004 IEEE Conference on Cybernetics and Intelligent Systems (CIS2004), IEEE International Conference on Cybernetics and Intelligent Systems, IEEE, Singapore, pp. 503-507.
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Based on analyses of characteristics of magneto-rheological (MR) damper, a hierarchical fuzzy intelligent controller is proposed for vibration control of an automotive vehicle with MR dampers. This controller consists of control level and coordination level. In the control level, a semiactive fuzzy logic controller is designed for each MR suspension system based on a hybrid control strategy of sky-hook control and ground-hook control. In the coordination level, a coordination controller is designed to coordinate the four independent semiactive fuzzy logic controllers by adjusting their output parameters according to the system feedback. To validate the results of hierarchical fuzzy intelligent control, a MR semiactive suspension control and test system is set up and is implemented on a mini bus, which is equipped with four controllable MR dampers. Test results indicate that the hierarchical fuzzy intelligent controller can effectively reduce the vertical vibration and improve the ride comfort and handle stability of automobile.
Lim, S.H., Furukawa, T., Durrant-Whyte, H. & Dissanayake, G. 2004, 'A time-optimal control strategy for pursuit-evasion games', Proceedings of IEEE International Conference on Robotics and Automation, IEEE International Conference on Robots and Automation, IEEE, New Orleans, USA, pp. 3962-3967.
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This paper presents a control strategy for the pursuer in the pursuit-evasion game problem when the evader behaves intelligently. The pursuer in the proposed technique does not try to react to the evader's behavior instantaneously. The proposed technique therefore does not yield instantaneous optimality but capture the evader in a time-efficient and robust fashion even when the evader is intelligent. The proposed technique was applied to two numerical examples and the results were compared to those by the conventional motion tracking algorithms. The results and comparison show that the proposed technique could capture the evader faster than the conventional motion tracking algorithms in both the examples.
Nguyen, A., Ha, Q.P., Huang, S. & Trinh, H.M. 2004, 'Observer-Based Decentralized Approach to Robotic Formation Control', Conference Proceedings, Australasian Conference on Robotics and Automation (ACRA 2004), Australasian Conference on Robotics and Automation, ARAA Australian Robotics & Automation Association, Canberra, Australia, pp. 1-8.
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Nichol, J.G., Palmer, L.R. & Waldron, K. 2004, 'Design of a Leg System for Quadruped Gallop', Proceedings of the 11th World Congress in Mechanism and Machine Science, IFToMM World Congress, China Machine Press, Tianjin, China, pp. 87-91.
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Ohio State (OSU) and Stanford Universities are cooperating to understand quadruped galloping through the design of a self-contained, biomimetic, galloping robot. The leg for this quadruped was first designed at Ohio State University (OSU). A second-generation leg, with the same functional geometry, has been designed and tested at Stanford University. The objective of these tests was to determine that the single leg would be capable of prolonged operation at a velocity of 5m/s, and that the control system, developed in simulation, would function under real-world conditions. The mechanical design of the quadruped is based on properties of biological quadruped animal legs. Important biomimetic design characteristics include minimal impact loss, elastic energy storage, and low inertia. The cable linkage, which works against a large spring to flex the knee, is uncoupled from the front-to-back hip actuator through a parallelogram-like cable mechanism. The controller developed for the leg is a direct adaptive fuzzy controller. The direct adaptive approach does not require system identification and can use heuristics to successfully control a complex system. With this controller, a single 2DOF leg constrained in yaw, pitch, roll and transverse translation can be successfully con-trolled. This controller was executed once each cycle at the top-of-flight. Parameters set by the controller were passed to PD controllers at each of the 2 joints: the hip and cable-actuated knee. The control of this leg required only 7×5×3 = 105 rules, each with a corresponding output for thigh and knee angle. This controller was implemented on an embedded processor attached to the leg. The leg reached a speed of 3 m/s. Modifications to the leg will increase this speed. The controller successfully adapted to the leg
Singh, S.P. & Waldron, K. 2004, 'Design and Evaluation of an Integrated Planar Localization Method for Desktop Robotics', Proceedings of the 2004 IEEE International Congress on Robotics and Automation, IEEE International Conference on Robots and Automation, IEEE, New Orleans, USA, pp. 1109-1114.
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Localization and measurement of displacement are critical aspects to the operation and control of mobile robots. The motion of desktop robots, a class of mobile robots designed for use on a table, can be considered a special case of the general localization problem since the vehicle is primarily operated over a flat surface. Using the assumption that the motion of a desktop robot is essentially planar, this paper presents a novel method that senses the motion of two points to obtain both the position and orientation of the robot in two-dimensional space. The paper details how this method can be implemented using low-cost, off-the-shelf sensor hardware components and demonstrates its application in the Desktop-Bot, a compact desktop robot. Experimental testing validated features of this planar localization such as: estimation with minimal mean error (or drift), no external sensing hardware apparatus (i.e., on-board sensing), fast-update rates (?50 Hz) and robustness to external occlusion.
Skinner, B., Nguyen, H.T. & Liu, D. 2004, 'Performance Study of a Multi-Deme Parallel Genetic Algorithm with Adaptive Mutation', Proceedings of the 2nd International Conference on Autonomous Robots and Agents (ICARA'04), International Conference on Autonomous Robots and Agents, Massey University, Palmerston North, New Zealand, pp. 88-94.
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Takezawa, S., Herath, H.D. & Dissanayake, G. 2004, 'SLAM in Indoor Environments with Stereo Vision', 2004 IEEE/RSJ International Conference on Intelligent Robots and Systems, 2004 (IROS 2004). Proceedings - Volume 2, IEEE/RSJ International Conference on Intelligent Robots and Systems, IEEE, Sendai, Japan, pp. 1866-1871.
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This paper proposes a method for simultaneous localisation and mapping (SLAM) in an indoor environment using stereo vision. Specially designed artificial landmarks distributed in the environment are observed and extracted from a camera image. The disparity map obtained from the stereo vision system is used to obtain the ranges to these landmarks. The main contribution of the paper is the formulation of the mathematical framework for SLAM for a robot moving on a planar surface among landmarks distributed in three dimensional space. The paper also presents the results of experiments conducted using a pioneer robot and a Triclops stereo vision system. It is demonstrated that accurate robot and feature locations can be obtained using the proposed technique.
Tran, T., Ha, Q.P. & Dissanayake, G. 2004, 'New Wavelet-Based Pitch Detection Method for Human-Robot Voice Interface', Proceedings of IROS2004 The 2004IEEE/RSJ International Conference on Intelligent Robots and Systems, IEEE/RSJ International Conference on Intelligent Robots and Systems, IEEE, Sendai, Japan, pp. 527-532.
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Speech activated interface between human and autonomous/semi-autonomous systems requires accurate voice detection and recognition. In this area, pitch and end-point detection is of vital importance. This paper presents a new method for pitch detection based on the phase of the continuous wavelet transform. The advantage of the proposed technique is that it can serve not only as an accurate pitch detector, but also can offer an efficient solution to the end-point detection problem. Experimental results are provided for the detection of pitch periods and end points in a neural-network based voice enabled wheelchair system.
Vidal-Calleja, T., Andrade-Cetto, J. & Sanfeliu, A. 2004, 'Conditions for suboptimal filter stability in SLAM', 2004 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS), pp. 27-32.
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In this article, we show marginal stability in SLAM, guaranteeing convergence to a non-zero mean state error estimate bounded by a constant value. Moreover, marginal stability guarantees also convergence of the Riccati equation of the one-step ahead state error covariance to at least one psd steady state solution. In the search for real-time implementations of SLAM, covariance inflation methods produce a suboptimal filter that eventually may lead to the computation of an unbounded state error covariance. We provide tight constraints in the amount of decorrelation possible, to guarantee convergence of the state error covariance, and at the same time, a linear-time implementation of SLAM.
Waldron, K. & Abdallah, M.E. 2004, 'Coordination of an Unmanned Vehicle with Active Suspension Over Extreme Terrain', Proceedings of SPIE, Vol. 5083: Proceedings of Unmanned Ground Vehicle Technology V, Unmanned Ground Vehicle Technology V, SPIE, Orlando, USA, pp. 1-9.
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Active suspension is now a well-tried technology in road vehicles. It has been installed on a HMMV and demonstrated to significantly improve performance in rough road conditions. This capability presents an opportunity for improved mobility in off-road conditions. The challenge is to devise a means of translating the desired trajectory of the vehicle into commands to the suspension actuators and the traction motors in an optimal, or near optimal manner. In this paper we describe part of a software architecture that was developed to enable such performance from a six-wheeled vehicle with active suspension and independent wheel drives. The vehicle was a concept developed under the DARPA Unmanned Ground Combat Vehicle Program.
Waldron, K. & Kallem, V. 2004, 'Control Modes for a Three-Dimensional Galloping Machine', Proceedings of DETC 2004: the 28th Biennial Mechanisms and Robotics Conference, International Design Engineering Technical Conferences and Computers and Information in Engineering Conference, ASME, Salt Lake City, USA, pp. 1525-1533.
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A set of relationships are developed to estimate the effects of control inputs on different axes of a galloping machine. It is demonstrated that control must be approached on a stride cycle basis to avoid serious cross-coupling between degrees of freedom. It is also demonstrated that a somewhat different approach to the Raibert controller is necessary for galloping. The relationships developed are primarily useful to estimate sensitivities to different control approaches, and thereby develop useful design information. Their use is illustrated by calculating sensitivities for our KOLT galloping vehicle.
Waldron, K. & Nichol, J.G. 2004, 'Architectural Issues in Running Machines', Proceedings of ROMANSY 15, Montreal, Canada.
Zheng, T., Liu, D. & Wang, P. 2004, 'Priority Based Dynamic Multiple Robot Path Planning', Proceedings of the 2nd International Conference on Autonomous Robots and Agents (ICARA'04), International Conference on Autonomous Robots and Agents, Massey University, New Zealand, Palmerston North, New Zealand, pp. 373-378.
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