|
State-chain sequential feedback reinforcement learning for path planning of autonomous mobile robots
Xin Ma, Ya Xu, Guo-qiang Sun, Li-xia Deng, Yi-bin Li
Front. Inform. Technol. Electron. Eng., 2013, 14(3): 167-178.
https://doi.org/10.1631/jzus.C1200226
This paper deals with a new approach based on Q-learning for solving the problem of mobile robot path planning in complex unknown static environments. As a computational approach to learning through interaction with the environment, reinforcement learning algorithms have been widely used for intelligent robot control, especially in the field of autonomous mobile robots. However, the learning process is slow and cumbersome. For practical applications, rapid rates of convergence are required. Aiming at the problem of slow convergence and long learning time for Q-learning based mobile robot path planning, a state-chain sequential feedback Q-learning algorithm is proposed for quickly searching for the optimal path of mobile robots in complex unknown static environments. The state chain is built during the searching process. After one action is chosen and the reward is received, the Q-values of the state-action pairs on the previously built state chain are sequentially updated with one-step Q-learning. With the increasing number of Q-values updated after one action, the number of actual steps for convergence decreases and thus, the learning time decreases, where a step is a state transition. Extensive simulations validate the efficiency of the newly proposed approach for mobile robot path planning in complex environments. The results show that the new approach has a high convergence speed and that the robot can find the collision-free optimal path in complex unknown static environments with much shorter time, compared with the one-step Q-learning algorithm and the Q(λ)-learning algorithm.
|
|
Punjabi DeConverter for generating Punjabi from Universal Networking Language
Parteek Kumar, Rajendra Kumar Sharma
Front. Inform. Technol. Electron. Eng., 2013, 14(3): 179-196.
https://doi.org/10.1631/jzus.C1200061
DeConverter is core software in a Universal Networking Language (UNL) system. A UNL system has EnConverter and DeConverter as its two major components. EnConverter is used to convert a natural language sentence into an equivalent UNL expression, and DeConverter is used to generate a natural language sentence from an input UNL expression. This paper presents design and development of a Punjabi DeConverter. It describes five phases of the proposed Punjabi DeConverter, i.e., UNL parser, lexeme selection, morphology generation, function word insertion, and syntactic linearization. This paper also illustrates all these phases of the Punjabi DeConverter with a special focus on syntactic linearization issues of the Punjabi DeConverter. Syntactic linearization is the process of defining arrangements of words in generated output. The algorithms and pseudocodes for implementation of syntactic linearization of a simple UNL graph, a UNL graph with scope nodes and a node having un-traversed parents or multiple parents in a UNL graph have been discussed in this paper. Special cases of syntactic linearization with respect to Punjabi language for UNL relations like ‘and’, ‘or’, ‘fmt’, ‘cnt’, and ‘seq’ have also been presented in this paper. This paper also provides implementation results of the proposed Punjabi DeConverter. The DeConverter has been tested on 1000 UNL expressions by considering a Spanish UNL language server and agricultural domain threads developed by Indian Institute of Technology (IIT), Bombay, India, as gold-standards. The proposed system generates 89.0% grammatically correct sentences, 92.0% faithful sentences to the original sentences, and has a fluency score of 3.61 and an adequacy score of 3.70 on a 4-point scale. The system is also able to achieve a bilingual evaluation understudy (BLEU) score of 0.72.
|
|
Novel serpentine structure design method considering confidence level and estimation precision
Li-sheng Chen, Xiao-hua Luo, Jiao-jiao Zhu, Fan-chao Jie, Xiao-lang Yan
Front. Inform. Technol. Electron. Eng., 2013, 14(3): 222-234.
https://doi.org/10.1631/jzus.C1200297
Due to the importance of metal layers in the product yield, serpentine test structures are usually fabricated on test chips to extract parameters for yield prediction. In this paper, the confidence level and estimation precision of the average defect density on metal layers are investigated to minimize the randomness of experimental results and make the measured parameters more convincing. On the basis of the Poisson yield model, the method to determine the total area of all serpentine test structures is obtained using the law of large numbers and the Lindeberg-Levy theorem. Furthermore, the method to determine an adequate area of each serpentine test structure is proposed under a specific requirement of confidence level and estimation precision. The results of Monte Carlo simulation show that the proposed method is consistent with theoretical analyses. It is also revealed by wafer experimental results that the method of designing serpentine test structure proposed in this paper has better performance.
|
7 articles
|