The Experts below are selected from a list of 20940 Experts worldwide ranked by ideXlab platform
Zengqi Sun - One of the best experts on this subject based on the ideXlab platform.
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estimating biped gait using Spline based probability distribution Function with q learning
IEEE Transactions on Industrial Electronics, 2008Co-Authors: Changjiu Zhou, Zengqi SunAbstract:This paper studies the probability distribution Functions of the parameters to be learned and optimized in biped gait generation. By formulating the gait pattern generation into a multiobjective optimization problem with consideration of geometric and state constraints, dynamically stable and low energy cost biped gaits are generated and optimized by the proposed method, namely Spline-based Estimation of Distribution Algorithm (EDA) with Q-learning updating rule (EDA_S_Q). Instead of assuming variables as independent ones, the relationship between them is exploited by formulating the corresponding probability models with the Catmull-Rom cubic Spline Function. Such kind of Function is proved to be a suboptimal and adaptive realization of the cubic Spline Function and is capable of providing high-precision description. Moreover, the probability models are updated autonomously by Q-learning method, which is model-free and adaptive. Thus, EDA_S_Q can deal with complex probability distribution Functions without a prior knowledge about the distribution. The biped gait generated by EDA_S_Q has been verified using the simulation model of a humanoid soccer robot Robo-Erectus. It also shows that EDA_S_Q can generate the desired biped gaits autonomously in short learning epochs. An interpretation of the transition probability distribution achieved by EDA_S_Q provides us easy understanding for biped locomotion and better control in humanoid robots.
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biped gait optimization using Spline Function based probability model
International Conference on Robotics and Automation, 2006Co-Authors: Changjiu Zhou, Zengqi SunAbstract:A new estimation of distribution algorithm (EDA) with Spline kernel Function (EDA_S) is proposed to optimize biped gait for a nine-link humanoid robot. Gait synthesis of the biped locomotion is firstly formulated as a multi-constraint optimization problem with consideration of two objectives, including zero-moment point (ZMP) for dynamically stable locomotion and driving torque for energy efficiency. The parameters to be optimized are joint coordinates at transition poses between three successive phases. Rather than searching in joint angle permutation space directly, the proposed method approximates the probability distribution by Catmull-Rom (CR) cubic Spline Function and updates them with gradient descent learning strategy. The effectiveness of EDA_S for biped gait optimization has been successfully tested on the simulated model of a humanoid soccer robot. It is shown that the flexible kernel with the updating rule is able to remarkably accelerate the learning speed with comparison to the traditional EDA
Simon Wang - One of the best experts on this subject based on the ideXlab platform.
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vibration of shear deformable rectangular plates using a Spline Function rayleigh ritz approach
International Journal for Numerical Methods in Engineering, 1993Co-Authors: Simon Wang, Daniel J DaweAbstract:The prediction of the natural frequencies of vibration of rectangular plates or orthotropic laminates is described, through the use of B-Spline Functions as trial Functions in a Rayleigh-Ritz approach. Through-thickness shear deformation effects are included in the analysis and hence assumptions have to be made for the spatial variation over the plate middle surface of each of the lateral deflection and the two rotation components. Two versions of the Spline-Function Rayleigh-Ritz approach are described: in one of these the deflection and rotations are represented by Functions of the same polynomial order, whilst in the other a lower-order representation is used for each rotation component in one of the co-ordinate directions. It is shown in a number of applications that the former version leads to shear-locking behaviour whilst the latter version avoids this behaviour and is suitable for the analysis of both thick and thin plates.
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Vibration of shear-deformable beams using a Spline-Function approach
International Journal for Numerical Methods in Engineering, 1992Co-Authors: Daniel J Dawe, Simon WangAbstract:B-Spline Functions are used as trial Functions in a Rayleigh-Ritz analysis of the free vibration of shear-deformable Timoshenko beams. In a first approach it is demonstrated in numerical applications that when the lateral deflection and the cross-sectional rotation are represented by Functions of equal order the calculated natural frequencies are of good accuracy for stocky beams but can overestimate the true frequencies very considerably for slender beams. This is identified as a shear-locking difficulty and consideration of its causes points clearly to the adoption of a new displacement field in which the deflection is represented by a B-Spline Function which is one order higher than that used to represent the rotation. Numerical results using this new displacement field demonstrate good accuracy for both stocky and slender beams: the shear-locking difficulty is completely eliminated. This has clear significance for the analysis of shear-deformable plates and shells when using B-Spline Functions.
Izliana Abu Bakar - One of the best experts on this subject based on the ideXlab platform.
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free vibration of anti symmetric angle ply laminated conical shells
Composite Structures, 2015Co-Authors: K K Viswanathan, Saira Javed, K Prabakar, Zainal Abdul Aziz, Izliana Abu BakarAbstract:Abstract Free vibration of anti-symmetric angle-ply composite laminated conical shells is studied including shear deformation using Spline Function approximation. The equilibrium equations are formulated in terms of displacement and rotational Functions. These Functions are approximated using Bickley-type Splines to obtain the generalised eigenvalue problem with suitable boundary conditions. Parametric studies are made to analyse the effects of circumferential node number, length ratio and cone angle on the frequency parameter for different number of layers and materials with different ply orientations under two types of boundary conditions.
Changjiu Zhou - One of the best experts on this subject based on the ideXlab platform.
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estimating biped gait using Spline based probability distribution Function with q learning
IEEE Transactions on Industrial Electronics, 2008Co-Authors: Changjiu Zhou, Zengqi SunAbstract:This paper studies the probability distribution Functions of the parameters to be learned and optimized in biped gait generation. By formulating the gait pattern generation into a multiobjective optimization problem with consideration of geometric and state constraints, dynamically stable and low energy cost biped gaits are generated and optimized by the proposed method, namely Spline-based Estimation of Distribution Algorithm (EDA) with Q-learning updating rule (EDA_S_Q). Instead of assuming variables as independent ones, the relationship between them is exploited by formulating the corresponding probability models with the Catmull-Rom cubic Spline Function. Such kind of Function is proved to be a suboptimal and adaptive realization of the cubic Spline Function and is capable of providing high-precision description. Moreover, the probability models are updated autonomously by Q-learning method, which is model-free and adaptive. Thus, EDA_S_Q can deal with complex probability distribution Functions without a prior knowledge about the distribution. The biped gait generated by EDA_S_Q has been verified using the simulation model of a humanoid soccer robot Robo-Erectus. It also shows that EDA_S_Q can generate the desired biped gaits autonomously in short learning epochs. An interpretation of the transition probability distribution achieved by EDA_S_Q provides us easy understanding for biped locomotion and better control in humanoid robots.
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biped gait optimization using Spline Function based probability model
International Conference on Robotics and Automation, 2006Co-Authors: Changjiu Zhou, Zengqi SunAbstract:A new estimation of distribution algorithm (EDA) with Spline kernel Function (EDA_S) is proposed to optimize biped gait for a nine-link humanoid robot. Gait synthesis of the biped locomotion is firstly formulated as a multi-constraint optimization problem with consideration of two objectives, including zero-moment point (ZMP) for dynamically stable locomotion and driving torque for energy efficiency. The parameters to be optimized are joint coordinates at transition poses between three successive phases. Rather than searching in joint angle permutation space directly, the proposed method approximates the probability distribution by Catmull-Rom (CR) cubic Spline Function and updates them with gradient descent learning strategy. The effectiveness of EDA_S for biped gait optimization has been successfully tested on the simulated model of a humanoid soccer robot. It is shown that the flexible kernel with the updating rule is able to remarkably accelerate the learning speed with comparison to the traditional EDA
Daniel J Dawe - One of the best experts on this subject based on the ideXlab platform.
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vibration of shear deformable rectangular plates using a Spline Function rayleigh ritz approach
International Journal for Numerical Methods in Engineering, 1993Co-Authors: Simon Wang, Daniel J DaweAbstract:The prediction of the natural frequencies of vibration of rectangular plates or orthotropic laminates is described, through the use of B-Spline Functions as trial Functions in a Rayleigh-Ritz approach. Through-thickness shear deformation effects are included in the analysis and hence assumptions have to be made for the spatial variation over the plate middle surface of each of the lateral deflection and the two rotation components. Two versions of the Spline-Function Rayleigh-Ritz approach are described: in one of these the deflection and rotations are represented by Functions of the same polynomial order, whilst in the other a lower-order representation is used for each rotation component in one of the co-ordinate directions. It is shown in a number of applications that the former version leads to shear-locking behaviour whilst the latter version avoids this behaviour and is suitable for the analysis of both thick and thin plates.
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Vibration of shear-deformable beams using a Spline-Function approach
International Journal for Numerical Methods in Engineering, 1992Co-Authors: Daniel J Dawe, Simon WangAbstract:B-Spline Functions are used as trial Functions in a Rayleigh-Ritz analysis of the free vibration of shear-deformable Timoshenko beams. In a first approach it is demonstrated in numerical applications that when the lateral deflection and the cross-sectional rotation are represented by Functions of equal order the calculated natural frequencies are of good accuracy for stocky beams but can overestimate the true frequencies very considerably for slender beams. This is identified as a shear-locking difficulty and consideration of its causes points clearly to the adoption of a new displacement field in which the deflection is represented by a B-Spline Function which is one order higher than that used to represent the rotation. Numerical results using this new displacement field demonstrate good accuracy for both stocky and slender beams: the shear-locking difficulty is completely eliminated. This has clear significance for the analysis of shear-deformable plates and shells when using B-Spline Functions.