一类值函数激励学习的遗忘算法

大状态空间值函数的激励学习是当今国际激励学习领域的一个热点和难点的问题,将记忆心理中有关遗忘的基本原理引入值函数的激励学习,形成了一类适合于值函数激励学习的遗忘算法,首先简要介绍了解决马尔夫决策问题的基本概念,比较了离策略和在策略激励学习算法的差别,概述了标准的ＳＡＲＳＡ（λ）算法,在分析了人类记忆和遗忘的一些特征后,提出了一个智能遗忘准则,进而将ＳＡＲＳＡ（λ）算法改进为具有遗忘功能的Ｆorget-ＳＡＲＳＡ（λ）算法,最后给出了实结果。     

一类基于有效跟踪的广义平均奖赏激励学习算法

取消了平均奖赏激励学习的单链或互通MDPs假设,基于有效跟踪技术和折扣奖赏型SARSA(λ)算法,对传统的平均奖赏激励学习进行了推广,提出了一类广义平均奖赏激励学习算法,并对算法的性能进行了初步的比较实验。     

概率近似正确的强化学习算法解决连续状态空间控制问题

在线学习时长是强化学习算法的一个重要指标.传统在线强化学习算法如Q学习、状态–动作–奖励–状态–动作(state-action-reward-state-action,SARSA)等算法不能从理论分析角度给出定量的在线学习时长上界.本文引入概率近似正确(probably approximately correct,PAC)原理,为连续时间确定性系统设计基于数据的在线强化学习算法.这类算法有效记录在线数据,同时考虑强化学习算法对状态空间探索的需求,能够在有限在线学习时间内输出近似最优的控制.我们提出算法的两种实现方式,分别使用状态离散化和kd树(k-dimensional树)技术,存储数据和计算在线策略.最后我们将提出的两个算法应用在双连杆机械臂运动控制上,观察算法的效果并进行比较.     

Ensemble Algorithms in Reinforcement Learning

This paper describes several ensemble methods that combine multiple different reinforcement learning (RL) algorithms in a single agent. The aim is to enhance learning speed and final performance by combining the chosen actions or action probabilities of different RL algorithms. We designed and implemented four different ensemble methods combining the following five different RL algorithms: $Q$ -learning, Sarsa, actor–critic (AC), $QV$-learning, and AC learning automaton. The intuitively designed ensemble methods, namely, majority voting (MV), rank voting, Boltzmann multiplication (BM), and Boltzmann addition, combine the policies derived from the value functions of the different RL algorithms, in contrast to previous work where ensemble methods have been used in RL for representing and learning a single value function. We show experiments on five maze problems of varying complexity; the first problem is simple, but the other four maze tasks are of a dynamic or partially observable nature. The results indicate that the BM and MV ensembles significantly outperform the single RL algorithms.      

平均奖赏MDP的在策略无模型激励学习算法

本文以随机逼近的形式,提出了一些用于求解平均奖赏Markov决策过程系统方程的在策略无模型激励学习算法,这些算法与广泛且成功应用于折扣奖赏MDP的SARSA（λ）类算法相似,为比较这些新算法的性能,本文还给出了一些初步的实验结果。     

Reinforcement Learning Soccer Teams with Incomplete World Models

We use reinforcement learning (RL) to compute strategies for multiagent soccer teams. RL may profit significantly from world models (WMs) estimating state transition probabilities and rewards. In high-dimensional, continuous input spaces, however, learning accurate WMs is intractable. Here we show that incomplete WMs can help to quickly find good action selection policies. Our approach is based on a novel combination of CMACs and prioritized sweeping-like algorithms. Variants thereof outperform both Q()-learning with CMACs and the evolutionary method Probabilistic Incremental Program Evolution (PIPE) which performed best in previous comparisons.     

折扣与无折扣MDPs:一个基于SARSA(λ)算法的实例分析

分析了折扣激励学习存在的问题,对MDPs的SARSA(λ)算法进行了折扣的比较实验分析,讨论了平均奖赏常量对无折扣SARSA(()算法的影响。     

Integrating temporal difference methods and self-organizing neural networks for reinforcement learning with delayed evaluative feedback

This paper presents a neural architecture for learning category nodes encoding mappings across multimodal patterns involving sensory inputs, actions, and rewards. By integrating adaptive resonance theory (ART) and temporal difference (TD) methods, the proposed neural model, called TD fusion architecture for learning, cognition, and navigation (TD-FALCON), enables an autonomous agent to adapt and function in a dynamic environment with immediate as well as delayed evaluative feedback (reinforcement) signals. TD-FALCON learns the value functions of the state-action space estimated through on-policy and off-policy TD learning methods, specifically state-action-reward-state-action (SARSA) and Q-learning. The learned value functions are then used to determine the optimal actions based on an action selection policy. We have developed TD-FALCON systems using various TD learning strategies and compared their performance in terms of task completion, learning speed, as well as time and space efficiency. Experiments based on a minefield navigation task have shown that TD-FALCON systems are able to learn effectively with both immediate and delayed reinforcement and achieve a stable performance in a pace much faster than those of standard gradient-descent-based reinforcement learning systems.     

Self-learning fuzzy logic controllers for pursuit-evasion differential games

This paper addresses the problem of tuning the input and the output parameters of a fuzzy logic controller. The system learns autonomously without supervision or a priori training data. Two novel techniques are proposed. The first technique combines Q(λ)-learning with function approximation (fuzzy inference system) to tune the parameters of a fuzzy logic controller operating in continuous state and action spaces. The second technique combines Q(λ)-learning with genetic algorithms to tune the parameters of a fuzzy logic controller in the discrete state and action spaces. The proposed techniques are applied to different pursuit-evasion differential games. The proposed techniques are compared with the classical control strategy, Q(λ)-learning only, reward-based genetic algorithms learning, and with the technique proposed by Dai et al. (2005) [19] in which a neural network is used as a function approximation for Q-learning. Computer simulations show the usefulness of the proposed techniques.     

场景图谱驱动目标搜索的多智能体强化学习

针对强化学习在视觉语义导航任务中准确率低,导航效率不高,容错率太差,且部分只适用于单智能体等问题,提出一种基于场景先验的多智能体目标搜索算法。该算法利用强化学习,将单智能体系统拓展到多智能体系统上将场景图谱作为先验知识辅助智能体团队进行视觉探索,利用集中式训练分布式探索的多智能体强化学习的方法以大幅度提升智能体团队的准确率和工作效率。通过在AI2THOR中进行训练测试,并与其他算法进行对比证明此方法无论在目标搜索的准确率还是效率上都优先于其他算法。     

Robust reinforcement learning

This letter proposes a new reinforcement learning (RL) paradigm that explicitly takes into account input disturbance as well as modeling errors. The use of environmental models in RL is quite popular for both offline learning using simulations and for online action planning. However, the difference between the model and the real environment can lead to unpredictable, and often unwanted, results. Based on the theory of H(infinity) control, we consider a differential game in which a "disturbing" agent tries to make the worst possible disturbance while a "control" agent tries to make the best control input. The problem is formulated as finding a min-max solution of a value function that takes into account the amount of the reward and the norm of the disturbance. We derive online learning algorithms for estimating the value function and for calculating the worst disturbance and the best control in reference to the value function. We tested the paradigm, which we call robust reinforcement learning (RRL), on the control task of an inverted pendulum. In the linear domain, the policy and the value function learned by online algorithms coincided with those derived analytically by the linear H(infinity) control theory. For a fully nonlinear swing-up task, RRL achieved robust performance with changes in the pendulum weight and friction, while a standard reinforcement learning algorithm could not deal with these changes. We also applied RRL to the cart-pole swing-up task, and a robust swing-up policy was acquired.     

Real-world reinforcement learning for autonomous humanoid robot docking

Reinforcement learning (RL) is a biologically supported learning paradigm, which allows an agent to learn through experience acquired by interaction with its environment. Its potential to learn complex action sequences has been proven for a variety of problems, such as navigation tasks. However, the interactive randomized exploration of the state space, common in reinforcement learning, makes it difficult to be used in real-world scenarios. In this work we describe a novel real-world reinforcement learning method. It uses a supervised reinforcement learning approach combined with Gaussian distributed state activation. We successfully tested this method in two real scenarios of humanoid robot navigation: first, backward movements for docking at a charging station and second, forward movements to prepare grasping. Our approach reduces the required learning steps by more than an order of magnitude, and it is robust and easy to be integrated into conventional RL techniques.     

基于启发式强化学习的动态CRE偏置选择算法

随着通信用户数量的不断增长,低功率基站逐渐出现负载不均衡问题,小区边缘用户受到的干扰逐步增加,从而导致整个小区的通信质量降低。为解决该问题,针对双层异构网络场景,提出一种基于启发函数进行小区范围扩展(CRE)偏置值动态选择的HSARSA(λ)算法。利用启发函数改进强化学习中的SARSA(λ)算法,通过该算法寻找出最优CRE偏置值,以缓解宏基站高热点负载压力并提高网络容量。仿真结果表明,相比SARSA(λ)和Q-Learning算法,HSARSA(λ)算法的边缘用户吞吐量分别提高约7%和12%,系统能效分别提高约11%与13%,系统通信质量得到较大提升。     

Supervised fuzzy reinforcement learning for robot navigation

This paper addresses a new method for combination of supervised learning and reinforcement learning (RL). Applying supervised learning in robot navigation encounters serious challenges such as inconsistent and noisy data, difficulty for gathering training data, and high error in training data. RL capabilities such as training only by one evaluation scalar signal, and high degree of exploration have encouraged researchers to use RL in robot navigation problem. However, RL algorithms are time consuming as well as suffer from high failure rate in the training phase. Here, we propose Supervised Fuzzy Sarsa Learning (SFSL) as a novel idea for utilizing advantages of both supervised and reinforcement learning algorithms. A zero order Takagi–Sugeno fuzzy controller with some candidate actions for each rule is considered as the main module of robot's controller. The aim of training is to find the best action for each fuzzy rule. In the first step, a human supervisor drives an E-puck robot within the environment and the training data are gathered. In the second step as a hard tuning, the training data are used for initializing the value (worth) of each candidate action in the fuzzy rules. Afterwards, the fuzzy Sarsa learning module, as a critic-only based fuzzy reinforcement learner, fine tunes the parameters of conclusion parts of the fuzzy controller online. The proposed algorithm is used for driving E-puck robot in the environment with obstacles. The experiment results show that the proposed approach decreases the learning time and the number of failures; also it improves the quality of the robot's motion in the testing environments.     

Reinforcement learning system based on heuristics free state focusing

We discuss the role of state focus in reinforcement learning (RL) systems that are applicable to mechanical systems including robots. Although the concept of the state focus is similar to attention/focusing in visual domains, its implementation requires some theoretical background based on RL. We propose an RL system that effectively learns how to choose the focus simultaneously with how to achieve a task. This RL system does not need heuristics for the adaptation of its focus. We conducted a capture experiment to compare the learning speed between the proposed system and the traditional systems, SARSAs, and conducted a navigation experiment to confirm the applicability of the proposed system to a realistic task. In the capture experiment, the proposed system learned faster than SARSAs. We visualized the developmental process of the focusing strategy in the proposed system using a Q-value analysis technique. In the navigation task, the proposed system demonstrated faster learning than SARSAs in the realistic task. The proposed system is applicable to a wide class of RLs that are applicable to mechanical systems including robots.     

Application of reinforcement learning for agent-based production scheduling

Reinforcement learning (RL) has received some attention in recent years from agent-based researchers because it deals with the problem of how an autonomous agent can learn to select proper actions for achieving its goals through interacting with its environment. Although there have been several successful examples demonstrating the usefulness of RL, its application to manufacturing systems has not been fully explored yet. In this paper, Q-learning, a popular RL algorithm, is applied to a single machine dispatching rule selection problem. This paper investigates the application potential of Q-learning, a widely used RL algorithm to a dispatching rule selection problem on a single machine to determine if it can be used to enable a single machine agent to learn commonly accepted dispatching rules for three example cases in which the best dispatching rules have been previously defined. This study provided encouraging results that show the potential of RL for application to agent-based production scheduling.     

Convergence Results for Single-Step On-Policy Reinforcement-Learning Algorithms

An important application of reinforcement learning (RL) is to finite-state control problems and one of the most difficult problems in learning for control is balancing the exploration/exploitation tradeoff. Existing theoretical results for RL give very little guidance on reasonable ways to perform exploration. In this paper, we examine the convergence of single-step on-policy RL algorithms for control. On-policy algorithms cannot separate exploration from learning and therefore must confront the exploration problem directly. We prove convergence results for several related on-policy algorithms with both decaying exploration and persistent exploration. We also provide examples of exploration strategies that can be followed during learning that result in convergence to both optimal values and optimal policies.     

Continuous control actions learning and adaptation for robotic manipulation through reinforcement learning

Autonomous Robots - This paper presents a learning-based method that uses simulation data to learn an object manipulation task using two model-free reinforcement learning (RL) algorithms. The...     

强化学习算法与应用综述

强化学习是机器学习领域的研究热点, 是考察智能体与环境的相互作用, 做出序列决策、优化策略并最大化累积回报的过程. 强化学习具有巨大的研究价值和应用潜力, 是实现通用人工智能的关键步骤. 本文综述了强化学习算法与应用的研究进展和发展动态, 首先介绍强化学习的基本原理, 包括马尔可夫决策过程、价值函数、探索-利用问题. 其次, 回顾强化学习经典算法, 包括基于价值函数的强化学习算法、基于策略搜索的强化学习算法、结合价值函数和策略搜索的强化学习算法, 以及综述强化学习前沿研究, 主要介绍多智能体强化学习和元强化学习方向. 最后综述强化学习在游戏对抗、机器人控制、城市交通和商业等领域的成功应用, 以及总结与展望.